INTRODUCTION TO GROWING

WHAT IS HYDROPONICS?

Hydroponics is a subset of hydroculture and is a method of growing plants using mineral nutrient solutions, in water, without soil. Terrestrial plants may be grown with their roots in the mineral nutrient solution only or in an inert medium, such as perlite, gravel, mineral wool, expanded clay or coconut husk.

Researchers discovered in the 18th century that plants absorb essential mineral nutrients as inorganic ions in water. In natural conditions, soil acts as a mineral nutrient reservoir but the soil itself is not essential to plant growth. When the mineral nutrients in the soil dissolve in water, plant roots are able to absorb them. When the required mineral nutrients are introduced into a plant’s water supply artificially, soil is no longer required for the plant to thrive.

Almost any terrestrial plant will grow with hydroponics. Hydroponics is also a standard technique in biology research and teaching.

Advantages of Hydroponics

No soil is needed for hydroponics
The water stays in the system and can be reused – thus, lower water costs
It is possible to control the nutrition levels in their entirety – thus, lower nutrition costs
No nutrition pollution is released into the environment because of the controlled system
Stable and high yields
Pests and diseases are easier to get rid of than in soil because of the container’s mobility
It is easier to harvest
Disadvantages of Hydroponics
Without soil as a buffer, any failure to the hydroponic system leads to rapid plant death. Other disadvantages include pathogen attacks such as damp-off due to Verticillium wilt caused by the high moisture levels associated with hydroponics and over watering of soil based plants. Also, many hydroponic plants require different fertilizers and containment systems.

Hydroponic Techniques
Continuous-flow solution culture

In continuous-flow solution culture, the nutrient solution constantly flows past the roots.

A popular variation is the nutrient film technique or NFT, whereby a very shallow stream of water containing all the dissolved nutrients required for plant growth is recirculated past the bare roots of plants in a watertight thick root mat, which develops in the bottom of the channel, has an upper surface that, although moist, is in the air. Subsequent to this, an abundant supply of oxygen is provided to the roots of the plants.

A properly designed NFT system is based on using the right channel slope, the right flow rate, and the right channel length.

The main advantage of the NFT system over other forms of hydroponics is that the plant roots are exposed to adequate supplies of water, oxygen, and nutrients. In all other forms of production, there is a conflict between the supply of these requirements, since excessive or deficient amounts of one results in an imbalance of one or both of the others. NFT, because of its design, provides a system where all three requirements for healthy plant growth can be met at the same time, provided that the simple concept of NFT is always remembered and practised. The result of these advantages is that higher yields of high-quality produce are obtained over an extended period of cropping.

A downside of NFT is that it has very little buffering against interruptions in the flow, e.g., power outages. But, overall, it is probably one of the more productive techniques.

Aeroponics

Aeroponics is a system wherein roots are continuously or discontinuously kept in an environment saturated with fine drops (a mist or aerosol) of nutrient solution. The method requires no substrate and entails growing plants with their roots suspended in a deep air or growth chamber with the roots periodically wetted with a fine mist of atomized nutrients.

The advantage of aeroponics is that suspended aeroponic plants receive 100% of the available oxygen and carbon dioxide to the roots zone, stems, and leaves,thus accelerating biomass growth and reducing rooting times.

NASA research has shown that aeroponically grown plants have an 80% increase in dry weight biomass (essential minerals) compared to hydroponically grown plants. Aeroponics used 65% less water than hydroponics. NASA also concluded that aeroponically grown plants requires the nutrient input compared to hydroponics. Unlike hydroponically grown plants, aeroponically grown plants will not suffer transplant shock when transplanted to soil, and offers growers the ability to reduce the spread of disease and pathogens.

Passive Hydroponics

Passive sub-irrigation, also known as passive hydroponics or semi-hydroponics, is a method wherein plants are grown in an inert porous medium that transports water and fertilizer to the roots by capillary action from a separate reservoir as necessary, reducing labour and providing a constant supply of water to the roots. In the simplest method, the pot sits in a shallow solution of fertilizer and water or on a capillary mat saturated with nutrient solution. The various hydroponic media available, such as expanded clay and coconut husk, contain more air space than more traditional potting mixes, delivering increased oxygen to the roots.

Additional advantages of passive hydroponics are the reduction of root rot and the additional ambient humidity provided through evaporations.

Ebb and Flow/Flood and Drain

In its simplest form, there is a tray above a reservoir of nutrient solution. Either the tray is filled with growing medium (clay granules being the most common) and planted directly or pots of medium stand in the tray. At regular intervals, a simple timer causes a pump to fill the upper tray with nutrient solution, after which the solution drains back down into the reservoir. This keeps the medium regularly flushed with nutrients and air. Once the upper tray fills past the drain stop, it begins recirculating the water until the timer turns the pump off, and the water in the upper tray drains back into the reservoirs.

Run To Waste

In a run to waste system, nutrient and water solution is periodically applied to the medium surface. This may be done in its simplest form, by manually applying a nutrient-and-water solution one or more times per day in a container of inert growing media, such as rockwool, perlite, vermiculite, coco fibre, or sand. In a slightly more complex system, it is automated with a delivery pump, a timer and irrigation tubing to deliver nutrient solution with a delivery frequency that is governed by the key parameters of plant size, plant growing stage, climate, substrate, and substrate conductivity, pH, and water content.

Deep Water Culture

The hydroponic method of plant production by means of suspending the plant roots in a solution of nutrient-rich, oxygenated water. Traditional methods favor the use of plastic buckets and large containers with the plant contained in a net pot suspended from the centre of the lid and the roots suspended in the nutrient solution. The solution is oxygen saturated from an air pump combined with porous stones. With this method, the plants grow much faster because of the high amount of oxygen that the roots receive.

SUMMER GROWING

During the summer months, many growers struggle to control the environment in their grow room. However, you need not be one of them. Here we provide an overview of the most common problems we have come across and offer advice on how you can deal with them enabling you to grow strong and healthy plants!

Temperature
As you would expect, a scorching temperature outside combined with the heat from your grow lights can cause temperatures to accumulate rapidly in your grow room. However, if you want strong and healthy plants, its important that you keep your grow room temperature between 22-28C.

Consequences of high temperatures in your grow room
If the temperature in your grow room is too high (above the 30C), your plants will suffer. Some of the most common problems include:
Plants appear stretched as the inter-node distance increases.
Airy flowers/poor fruit quality.
Internal cell and enzyme damage, resulting in poor growth and unhealthy plants.
Monitoring the temperature of your grow room
Always use a quality thermometer to measure the air temperature of your grow room. We recommend using a digital thermometer that also monitors humidity. For an accurate reading, its important to position your thermometer so that it is out of direct light.

Ensuring the air in your grow room is well mixed will also improve the readings you get from your thermometer. The use of air circulators is an inexpensive and effective way of doing this.

Removing hot air from your grow room
During the summer months, it is essential that you remove hot air from your grow room. Using an appropriately sized extractor fan will allow you to remove the hot air and duct it out of your grow room. As heat rises, you should place your extractor fan at the top of your room.

It is important to remember that the lights in your room are the main heat generators. So the more lights you have, the larger your extractor fan will have to be.

Supply your grow room with cooler air
As well as removing hot air, you also need to supply the room with fresh, cooler air. This can be done by using another inline fan to pump fresh, carbon dioxide rich air into your room.

For effective temperature control, we recommend wiring your extractor fan to a thermostatic fan speed controller.

Indoor grow lights
Your indoor grow lights are likely to generate a lot of heat. As mentioned, it is important that you have good air exchange and keep the air well mixed to avoid heat build-up. This can be done using a pedestal fan to move the air under the lights. Heat shields are also a good way of avoiding a high temperature under lights, particularly if your grow room has low ceilings because they disperse heat very well.

The use of air-cooled reflectors will effectively remove the heat that your grow lights emit. They are easy to use; you simply position your extractor fan so that it forces air through the reflector and over your lamp.

The time of day your lights come on is important. In the hotter months, it is advisable that you start the light cycle in the evening, and running the lights through the night. This allows you to bring in cooler night-time air into your room during the light cycle. It also avoids extreme mid-day temperatures.

If you have dimmable electronic ballasts, you have the option to lower the light intensity, which in turn lowers the heat output. This is a very useful tool during periods of high temperature when plant can really suffer. If you have multiple lights, you can alternate them to come on and off a few times during the light cycle. Turning lights off is a last resort, but it will help to drop the temperature to a more manageable level.

Air Conditioners
If your grow room temperature is constantly high and growth is affected, you should invest in an air conditioner. An air conditioner removes water from the air and lowers humidity (see below). A humidifier may be needed when using air conditioning units.

Humidity
For healthy plant growth, you should aim for a relative humidity (RH) of 50-70%. High heat often causes low humidity in summer grow rooms. If humidity drops below 50%, your plants will suffer. In particular, the roots will take up a lot more water and leave behind too much nutrient in the tank/pot. This can cause over-fertilisation; resulting in leaf tips turning brown, curling down and dying (leading to an overall drop in yield).

Using a humidifier in summer is the most efficient way to increase humidity.

Nutrient Solution Temperature
The ideal temperature for the root zone is between 18-21C. During the summer, it is important that the temperature of your nutrient solution does not increase beyond 25C. If this happens, it will affect the oxygen content of the water, nutrient uptake and overall plant growth. Covering your tank with black and white reflective sheeting (white side up) can protect the nutrient from over heating.

To make sure the oxygen does stay at a good level in the nutrient solution, use an air pump and air stone. We stock a range of sizes. Adding hydrogen peroxide to the nutrient solution also increases the oxygen content.

Propagation
The ideal propagator temperature is 20-26C. When the temperature rises above 28C, rooting rates suffer. If the temperature inside the propagator does get too high, move your propagation light higher.

Pests
In dry, hot conditions, pests such as spider mites and thrips can reproduce rapidly. It is highly recommended that you deal with these pests straight away. A regular check of the underside of your leaves every 3-5 days is advisable.

GROWING ORGANICALLY

What does organic mean?
Other than the traditional scientific definition of containing carbon, organic growing is a term now used to describe a more natural, holistic approach to growing plants. This encompasses avoiding the use of chemical pesticides, fungicides and artificial fertiliser/ liquid nutrients.

Typically, in an organic garden, the grower will be using an organic growing media that is free from chemicals and is biodegradable along with dry or liquid nutrients and additives that contain plant or animal extracts, not refined mineral salts (chemicals).

How does organics work?
When you grow a plant using organic growing media and nutrients, there are some differences in the way the plant has access to nutrition in comparison to hydroponics. In hydroponics, the plants are given nutrients that are already in an available form. This means the nutrients are taken up into the roots straight away. When you water your soil with an organic nutrient, most of the elements that end up in and around the root zone cannot be taken up straight away by the plant. The elements need to be converted into a form that the plant can use – this is done by small microbes in the soil (bacteria, enzymes, fungi and protozoa) and the process is known as mineralisation. This means that the health of your soil becomes very important as it is a living system that nourishes the plant.

Organics Pros and Cons:
Deciding to grow organically is often a conscious choice to try and grow plants in the most natural way possible. But in reality, there are not many extra benefits when compared to hydroponic growing. Organic growing is slower than hydro – especially in vegetative growth – but it is a lot easier to maintain than a hydroponic system. Controlling the nutrition in the root zone is more difficult because of the lag time between using the nutrients and them being available to the plant. This uncertainty with feeding is often counteracted by using nutrients every other watering or using water only once a week. If you ask an avid organic gardener, they will tell you that you develop a feel for what the plants need. It is this predictive interaction with the plants that a lot of organic growers learn to love and take pleasure in.

Organic Certification
There are many brands of nutrients and soils that will claim to be organic. To be certain that you are using quality products, make sure that they have certification from a recognised organisation. There are many organisations world wide that will approve a product as organic, but you must be aware that these organisations have different standards. Look for one of the following widely accepted organisations to be sure of its quality: Soil Association – the UKs leading certification organisation OMRI Organic Materials Review Institute, principal organisation in the USA CU – The Control Union Certifications organisation, maintains worldwide supervision of input products that are used in organic farming.

DESIGNING YOUR GROW ROOM

You want to build your very own grow room, but dont really know where to start. Like others new to soil-less gardening, you may be confused by the jargon that is sometimes associated with hydroponics. Well, if so, this article is perfect for you. With the jargon kept to a minimum, it will help you to establish a better understanding of indoor growing.

1. Laying the foundations

If there is one golden rule to setting up a grow room, it is careful planning. You have two options in deciding your room type; a grow tent or a custom built grow room. Any structural work needed to get your room up and running should be made a priority. A well designed grow room will make your indoor gardening experience much more enjoyable. Remember that the size of your grow room is the first step in deciding what equipment you will need. The size of your room will determine how many lights are suitable, what type of ventilation system is necessary and what hydroponic system will be most appropriate. When planning your grow room you must ensure:
You have access to plenty of electricity – ask yourself whether there are enough plug sockets for your needs.
You have a good water supply – this will stop your plants dying of thirst
You can ventilate the area – make sure you have access to fresh air and can eject wasted air.
Remember, modifications which are made late can be very messy!

2. Cultivating plants

A plant will only achieve its maximum potential if grown in the right environment. Bumper yields and healthy growth are dependent on three key factors:
Lighting
Air Exchange
Nutrient Management
Air exchange:

If a plant is unhealthy, it is usually a sign of poor air exchange. In fact, poor air exchange is the cause of at least 90% of growers problems that we diagnose and help rectify. Good air exchange will:
Reduce the risk of disease and pest attacks.
Help the roots of the plant take up water and nutrients.
Keep the temperature and humidity within an acceptable range.
Supply carbon dioxide to the plant.
An extractor fan is essential for maintaining good air exchange. All grow rooms should have one. Air exchange comes in two parts, an exhaust (active) and intake (active or passive). A passive intake is a vent. An active intake is fan which blows fresh air into the grow room. You should place each at opposite ends of your indoor garden. Situate the exhaust (active) at the top of your room to extract the hot air as it rises. Position the intake vent (active or passive) low down near the floor to draw in fresh cooler air.

Extractor fans vary in size. As a rule of thumb, the more lights your grow room has the larger the extractor fan youll need.

Nutrient management:

Media based and non-media based hydroponic systems usually contain little or no nutrients. Essential minerals, which all plants need, must therefore be supplied by you, the grower, in the form of a nutrient solution.

Nutrient solutions vary in strength. The strength of nutrient a plant requires will depend upon the type of plant and its growth stage. You can add nutrients to your reservoir based on the volume of water it holds. For more accurate control we would recommend measuring the strength of the solution with a conductivity meter, which will give you a reading of the Conductivity Factor (CF) or Electrical Conductivity (EC) of the solution. The higher the number, the stronger the nutrient solution.

The pH factor is also important as it determines how easily a plant can absorb the nutrients available in a solution. The quicker a plant can absorb the nutrients, the faster itll grow. A pH measure of 0-6 indicates a solution is acidic, 7 is neutral, while a reading of 8-14 will mean its alkaline. Most plants prefer a pH range of 5.5 to 6.5. You can test the pH using a basic pH kit.

You should test and adjust the CF and pH every day to suit your plants requirements.

Lighting intensity and spectral output:

Light is the one of the most important environmental factors – without it a plant cant survive. Remember, for a plant, light is basically food. Most indoor gardeners use artificial lighting to increase growth rates and achieve bumper yields. You should place artificial lights directly above your plants.

Dr Greens Tip:
Remember, increasing the amount of light increases heat. Dont let your room temperature exceed 30C as this will actually reduce yields!

3. Planning the crop

Probably the most exciting part of indoor growing is planning the crop. It will give you an idea of what you can achieve with your indoor garden.

Planning the crop involves:
Researching the plants you want to grow.
Deciding on the number of plants you want.
Choosing the system you wish to use.
When planning the crop, its important to remember that a high yield doesnt mean growing lots of plants. An overcrowded grow room will only result in unhealthy plants.

Dr Greens Tip:
If youre new to soil-less gardening, we recommend starting with Nutrient Film Technique (NFT) growing systems.

In brief:

Now you should be well on your way to building your very own indoor garden. But remember to:
Ensure all the necessary structural work is completed before you do anything.
Hang reflective sheeting on the walls if your room is custom built.
Install the intake and extractor fan.
Have a test run once the extractor fan and lighting equipment is in place.
Take note of any temperature and humidity changes.
Install timers, thermostats and humidistat (if required).
Pre soak media (if required).
Install your growing system.
Install all other electrical items, such as air pumps and nutrient heaters.
Bring in your plants.
Carefully monitor your grow room for the first 24 hours.

INDOOR GROW LIGHTS

Light is one of the most important factors to consider when growing plants. It is very simple – no light means no growth. In fact, as a general rule, the more light your plants have access to, the quicker they will grow and the more they will yield. The benefit of an indoor grow light is that it allows you to grow literally any plant, anywhere, anytime! However, to get the best out of your indoor grow light and growing it is helpful to understand the basic principles of light.

Spectrum

Anyone who has seen a rainbow will know that sunlight is made up of different colours. These colours of light can also be differentiated by their wavelength which is measured in nanometers (nm).

The human eye is most sensitive to light around the middle of the visible spectrum – between 500 and 600nm. Plants find wavelengths between 400 and 700nm useful for turning light into energy (photosynthesis), and this area is referred to as Photosythetically Active Radiation commonly abbreviated to PAR. While the human eye finds light at 555nm the most visible (thus more useful), plants find two distinct areas of the spectrum most useful the blue area between 400-460nm and the red area between 580-700nm.

Measuring Light

Lumens is a measurement of light intensity, and is often used to define the output from artificial lights. This is fine for lights to help us see in the dark, but becomes rather useless when measuring horticultural grow lights because lumens are measured according to what the eye is sensitive to. Using lumens is therefore not a correct representation of the properties of a lamp that are useful to plants.

Lux is often used by light-measuring devices and is simply a measurement of how many lumens fall on each square meter of surface. So an illumination of 50,000 lux is 50,000 lumens falling on each square meter. Lux measurements are useful for measuring intensity from grow lamps and can be used to determine an accurate height to position the light above the plants, or to check for lamp degradation. However, lux is still not a good measurement for determining the quality of light and how good it is for growing plants.

Professional growers and light manufacturers have switched from measuring light in lumens and lux, to photon count in the PAR area. Without going into too much detail, a photon is a particle of light. A blue photon has a short wavelength and does not have as much energy as a red photon – which has a long wavelength. The plant, however, is only interested in the number of photons (it does not use the energy in the photon for photosynthesis). A plant requires 8-10 photons to bind one molecule of CO2. So a blue 600W light produces less photons than a red 600W light and is less efficient for photosynthesis. However, you do need more than just red colours in your spectrum for a plant to grow healthily.

A device to measure photons is called a quantum meter. The total amount of photons – known as the photosynthetic photon flux (PPF) – from a lamp can be measured with a quantum meter to give you accurate data on the amount of photons per second coming from your lamp. Photons are counted in micromoles (mol) and in case you are interested, one mol is 602214150000000000 photons! The unit used for PPF is micromole/second (mol/s), and a good 600W HPS lamp will emit 1100 mol/s.

To summarise, if you have two lights and one has a higher lumen output, it is not an indication that it is better for growing plants. The most useful light output data is plant useable light measured in micromoles.
Day Length

The amount of light your plant receives in a 24 hour period is called the photoperiod or day length. Some plants use the photoperiod as a signal to know when to produce leaves, flowers or fruit. Using this signalling tool, indoor growers can alter the photoperiod using timers to control their lights and their plants. Long day lengths of 16-24 hours are most commonly used for vegetative growth, and short light cycles of 12 hours are used for flowering or fruiting. Most grow lights are too powerful for plug in timers, the solution to this this will be covered later.

Light and Environment

All lights produce some heat as well as light. When growing indoors this heat generated by the grow lights need to be removed using an extractor fan to keep the plants growing environment comfortable. If you position your light too close to your plants, the heat from the lamp may burn them. So, it is very important to correctly hang your growing lights.

Types of Grow Lights

There are two categories of lights commonly used for growing plants. These are fluorescent and high intensity discharge (HID).

Fluorescent Grow Lights

Fluorescent grow lights are more suitable for propagation and vegetative growth. They have good colour rendering properties (a high proportion of the light emitted is used by the plant) and produce less heat than HID grow lights (see below). This allows them to be placed closer to your plants to make the most of their output.

There are two types of fluorescent lights used for growing – Compact Fluorescent Lamps (CFL) and T5 lamps (aka tubes). CFLs are large energy saving lamps and have the electronics to ignite the lamp at their base. These can be screwed into a reflector or simply hung vertically above the crop. T-5s are the most efficient fluorescent tube light, and need separate electronics to ignite the lamps. These electronics are housed within T5 reflectors. Due to the size of the T5 tubes, they produce a very uniform level of light over a larger area in comparison to CFLs.

Compact Fluorescents are available in 150W and 250W, as well as a propagation lighting system utilising 2 x 55W PL lamps. T5s are available as 2ft 24W lamps and 4ft 54W lamps. These are available individually without a reflector or as an integrated lighting system with two, four or eight lamps.

Fluorescent lights are great for seedlings and cuttings, as plants at this stage do not need intense light. Both CFL and T5 are low intensity, so they need to be placed close to plants to be effective at promoting growth. If using fluorescent lights above propagators, do not place them too close as this will cause the internal propagator temperature to get too high.

The light emitted from a fluorescent lamp can vary depending on the lamp colour. Fluorescent lamps come in different colour variations differentiated by the Kelvin colour temperature scale. The Kelvin scale has become industry standard for differentiating commercial and domestic lighting, but is rarely referred to in horticultural lighting other than for fluorescent lamps.

Fluorescent lamps with a high Kelvin are mainly used for propagation or vegetative growth; these usually come in around 6400K. Lamps with a low Kelvin are used for flowering and usually emit light around 2700K. A mixture of both (1 x 27K for every 3 x 64K) is a good approach for vegetative growth , and the reverse (3 x 27K for every 1 x 64K) fruiting or flowering.

Dr Green’s Tips:

Due to their lower light output, fluorescent grow lights should not be used instead of HID lights during the flowering stage. However, they are effective as supplementary lighting when hung in between your plants with CFL lamp hangers, or as side lighting with T5s.
All of our fluorescent lights can be plugged into a timer to control the photoperiod. A relay or contactor is not necessary.
HID Grow Lights

HID (High Intensity Discharge) lighting is the most efficient way to convert electricity into light and is the most popular type of horticultural grow light. HID grow lights are available in a large choice of wattages; the most common are 250W, 400W, 600W and 10000W with the 600W being the most popular option. A HID grow light is made up of three parts:

1.The Ballast which contains the necessary electronics to ignite and run the lamp.
2.The Reflector that holds the lamp in position and reflects light down to the plants.
3.The Lamp which can be either a High Pressure Sodium (HPS) or Metal Halide (MH).

Ballasts

A ballast or power pack is at the heart of a HID lighting system. There are 2 types of ballast available – standard electromagnetic ballast and the more recent electronic or digital ballast. Both deliver a surge of electricity at a high voltage to ignite the HID lamp. After ignition, the ballast then regulates the electricity being delivered to the lamp for safe operation. Electronic ballasts are around 3-4% more efficient than electromagnetic ballasts, run quieter and can have dimming functions to control the lamp power.

Reflectors

HID reflectors come in all shapes and sizes, but are all designed to do one job reflect as much light as possible down onto your plants. The most efficient reflectors are about 95% efficient meaning of the original 100% light from the lamp, 95% is emitted by direct light from the lamp or reflected light from the reflector. Basically, even the best reflector will have around a 5% loss. A reflector should also help to create a uniform spread of light while avoiding hot spots of intense light. Some reflectors are sealed using a glass plate or tube and are air-cooled using an extractor fan to further reduce the heat emitted from the lamp and keep grow room temperatures down.

Lamps

Metal Halide – MH

Metal Halide (MH) lights produce a lot of light in the blue spectrum. This colour of light encourages plant growth, particularly green, leafy growth and keeps your plants short and compact. MH lamps produce a broad spectrum of light (more so than HPS) and a small amount of UV which can help improve the quality of your produce. However, MH lamps are not as efficient as HPS, producing around 30-40% less micromoles.

High Pressure Sodium – HPS

High Pressure Sodium (HPS) lamps emit mainly orange-red light. This band of light is best for fruiting and flowering plants but can also be used for vegetative plants with good results. HPS lamps are the most efficient grow light currently available and produce the best yields. Standard HPS lamps are slightly deficient in the blue spectrum; to supplement this you can use fluorescent lights or use a ratio of three HPS lamps to one MH lamp in the flowering period. Some HPS lamps are termed Dual Spectrum, which means that have an enhanced output in the blue spectrum. Dual spectrum lamps are touted as being an all-in-one veg and flower lamp, but their spectrum is still much more suited to flowering plants. Best results will be achieved using a MH lamp for vegetative growth and HPS lamp for flowering.

Dr Green’s Tips:

If you want to supplement your HPS with extra CFLs, use the 6400K Cool White lamps as these will provide the blue light your HPS is missing.
Switching from a HPS to a MH lamp in the last 1-2 weeks of the plants life cycle can greatly improve the quality of your produce by enhancing essential oil production.
Relays and Contactors

When a ballast starts up, it draws a large amount of electricity for a split second so that it ignites the lamp. This spike of high voltage is enough to burn out a standard plug-in timer, so to successfully turn a HID light on-and-off automatically, you need to use a relay or a contactor. These devices use the timer as a signal, and draw the power through a 13-amp plug, rather than through the timer. One 13-amp relay can switch 1 x 1000W, 3 x 600W, or 4 x 400W HID lighting systems. Contactors are more heavy duty than relays and are used for larger indoor gardens with 4 or more 600W lights.

Other Types of Grow Lights

New technologies currently trying to improve horticultural lighting are light emitting diodes (LEDs) and light emitting plasma (LEP).

LED’s

Unfortunately, there has been a glut of cheap LEDs that have been launched in the hydroponics market over the years that have all over-promised and under-delivered. Many companies make claims that their LEDs are more efficient than HPS, but currently there are still no LED units that can produce yields that are close to comparable.

However, LEDs are a very promising area for supplementing light to change or steer the plants growth. The benefit of LEDs is they can be tuned to a specific wavelength to trigger a certain response or enhance a particular growth stage.

The common LED grow lights on the market that have a mixture of blue and red LEDs say they are tuned to match the two PAR peaks and drive targeted photosynthesis, but they are missing all of the other wavelengths (colours) that plants also need. Interestingly, the most promising LEDs to come to market during 2012 are the full spectrum LEDs that are designed to produce light across the whole PAR spectrum. However, the diode wattage and unit cost still means LEDs are not able to replace HPS lamps.

LEP

Light emitting plasma has come to market for the purpose of solar simulation. They produce a very broad spectrum of light, including UVs, which is close to natural sunlight.

LEP units can be used on their own for vegetative growth but are lacking in the red spectrum to produce a good yield of fruits or flowers. They are very good for supplementary light, particularly for adding in UV light to improve quality which is missing from most HPS lamp. The market leaders in LEP technology is Gavita Holland and we are sure there will be some great further developments in LEP lighting systems over the coming years.

GOOD GROW ROOM PRACTICE IN SUMMER

With more than 15 years experience in the hydroponics industry, we have advised many growers on how to run successful grow rooms, all year round. During this time, we have found that growers tend to encounter more problems in summer. This is mainly due to higher temperatures. However, by following good grow room practices you can still grow strong and healthy plants in summer. Here we explain how:

Step By Step Summer Growing

1. Initial Checks

When you walk/look into your grow room, do a quick visual check and make sure that the lights are running, fans are on, and there are no obvious problems – such as puddles on the floor or Mylar hanging off the wall. You should also check that your plants look healthy. For instance, are your plants producing new shoots? Are they a nice colour, i.e. are they lush and vibrant? Does there appear to be any leaf curl?

2. Checking temperature and relative humidity

Both temperature and relative humidity have a great influence on your plants overall development. We recommend that you purchase a maximum/minimum thermo-hygrometer which will allow you to check the maximum and minimum temperature and relative humidity between your grow room visits.

For healthy plant growth, the ideal grow room temperature is between 22-28C. If your maximum temperature reaches 30C or more, you will need to think about ways to cool your room down. For example, you could upgrade your extractor fan. It may also be worth investing in air-cooled reflectors, an air conditioning unit and/or a humidifier. Turning off one of your lights is also an option.

Your plants will perform best when relative humidity is between 50-75%. If your minimum humidity is below 45%, you should think about ways of increasing this, for example by purchasing a humidifier or mist maker.

Running a grow room with a low relative humidity and high temperature is the cause of most problems growers encounter in summer. Both can cause your plants to become stressed through excess water loss. This, in turn, can initiate over-fertilization because your plants will use more water and leave behind nutrient. Consequently, this can result in leaf curl and burnt tips.

3. Now its time to check your nutrient solution

Ideally, you should aim for a nutrient temperature of approximately 21C. Purchase a good thermometer to keep track of the water temperature. If your nutrient solution is too hot (above 24C), try covering up your tank with reflective sheeting, which will help to reflect any heat/light that may heat your solution.

You will also need to check that your nutrient reservoir is set at the right pH and nutrient strength (CF) for the size/age of your plants. As a general guide, the ideal CF range is between 10-16 during the vegetative cycle and 16-24 in flowering.

As mentioned earlier, over-fertilization can be more prominent during summer, particularly in recirculating systems. If you find the CF is too high in your reservoir, dilute your nutrient with water. A flush of your system or growing media may be necessary.

However, if you find you have to add a lot of water every day, its likely that your relative humidity is too low. If so, we advise running your nutrient at a lower strength and that you consider investing in a humidifier.

If youre using an NFT system, make sure that your flow rate isnt too high or low, and if you use drippers turn the pump on quickly to make sure you have no blockages.

4. Time for checking your plants

We advise that you check your plants thoroughly at least once every three days, ideally every day if you can. When looking at the base of your plants, make sure that youre growing media isnt too wet or dry, and if youre growing in growing in an NFT system, such as the NFT Gro-Tank Kit, that the roots are healthy, i.e. plenty of white growth.

You will also need to check your plants for insects, which can be rife in summer. Look at the leaves of your plants from the base of the plant up. Insects, such as spider mite and thrips prefer to live and breed on the underside of leaves, so be sure to check here too. You may wish to purchase a magnifier to help you check and correctly identify insects.

If you find any insect activity, act quickly by either spraying the affected leaves/plants with an insect killer and/or remove extremely damaged leaves. Note: Insects can breed extremely fast when temperatures are high.

5. Dont forgot the final Checks

Below is a list of some final checks you should make before you leave your grow room:
Reset your maximum/minimum thermo-hygrometer by holding down the max/min button.
Be sure to check that all of your equipment is running, especially your pumps and fans.
Try to avoid leaving nutrients and additives in your grow room as they should be kept in the dark at around 20C (room temp).
Keep a clean and organised room by removing any dead leaves hanging from your plants. Take out any plant material you have removed – you dont want to create a breeding ground for insects and fungi.
Keeping a weekly record of your grow room environment and nutrient solution readings will help you to run your grow room efficiently. It will also assist in getting to the bottom of any problems quickly and concisely. Any large shift in nutrient strength or pH can visually manifest itself on the plant up to 7-10 days later, so make sure to keep a record of the previous 2-3 weeks.

ENVIRONMENT CONTROL

ODOUR CONTROL

With indoor gardening, there are many factors that contribute to grow room odour: heat and humidity, poor air circulation, pollen, plant material, hydroponic growing media, hydroponic nutrient solutions, organic sprays and nutrient additives. This document will help you to understand how you can eliminate bad odour and keep your indoor garden smelling fresh.

Carbon filters

Using a carbon filter is a popular method of odour removal and air purification. A good carbon filter is capable of filtering up to 99% of airborne odours. There is no residue smell and no added electrical cost associated with adding a filter to your exhaust system.

How does a carbon filter work?

A carbon filter is used in conjunction with an extractor fan, cleaning the air before it is removed from the grow room. This method helps ensure all stale air is exhausted. The extractor fan draws air through the carbon filter via a pre-filter cover designed to catch any large airborne particles. Air then travels through the screened side walls to the activated carbon. This is where the odour is cleaned and drawn out through the exhaust system.

Installing a carbon filter

Odour rises with warm air. For this reason, we recommend you install your extractor fan and carbon filter at the highest possible position in your grow room. Hint Activated Carbon is safe and non-toxic, which means carbon filters can be used in a grow room where cleansed air is recirculated. The use of this scrubber should be in addition to your grow filtration system. Scrubbing systems are achieved by attaching a carbon filter to an extractor fan. However, no ducting should be attached to channel the cleaned air outside the grow room. This method continually recirculates the grow room air; reducing dust, fungal spores and odours. With some particularly bad odour problems, a ventilation system and a separate carbon filter attached to a re-circulation system can be a very effective method of odour control. It is important to match the correct carbon filter to your extractor fan. For example; a 750m3/hr capacity extractor fan needs to be matched with a carbon filter capable of treating 750m3/hr of air or more. Do not try to use a lower capacity filter, it may be able to treat the odours but it will significantly reduce the efficiency of the extractor fan, resulting in high grow room temperatures and a short life expectancy for the fan. Likewise, pairing a large carbon filter with a small extractor fan will not result in better odour removal. Also, for a carbon filter to be effective, the relative humidity of the grow room air must be below 80%.
Ozone generators

Popular with many indoor gardeners, ozone generators are very efficient at eradicating bad odours. Ozone also destroys moulds and bacteria that can lead to poor plant health and reduced yields. In particular, ozone will help to suppress Botrytis/Flower rot.

How does ozone work?

When ozone gas comes into contact with odour, an oxygen atom splits off from the ozone molecule; oxidising it into harmless and non-odorous substances. Ozone binds with the odour molecules to neutralise it.

Is ozone safe?

In the UK, levels below 0.5 parts per million (ppm) are deemed safe. All of the ozone generators stocked by Dr Greens operate within this level. Installing an ozone generator Ozone generators are easy to install, lightweight, compact and have low running costs. There are two types of ozone generators; those that work best for seepage odours that are positioned outside of grow rooms, and those that are designed to work in-line with ducting runs in extraction/ventilation systems. Air fresheners Non-aerosol air fresheners will help remove unwanted odours, whilst adding a pleasant fragrance to your grow room. However, we would not recommend that you rely on air fresheners as a sole source of odour control – but they are handy when you have to mask an odour!

TEMPERATURE

During the hot summer months, it can be difficult to control the temperature in your grow room. This article advises you on how to maintain a temperature that promotes healthy plant growth.

How important is temperature?

Your plants are constantly processing energy 24 hours a day. In the light cycle they make and store sugars, during the dark cycle these sugars are transported throughout your plants. Your plants need a continuous energy supply in order to grow and mature. The speed at which your plants process energy is directly related to temperature.

What is the ideal temperature for plant healthy growth?

If you want your plants to grow quickly and stay healthy, its important that you keep them within their comfort zone. This is between 72-82F. Most plants are very comfortable up to 82F, but are sensitive to higher temperatures.

You can use a thermometer to measure the temperature of your grow room. Ideally, choose a thermometer that records the maximum and minimum temperature. Thisll allow you to monitor the hottest and coolest temperatures in your grow room over a twenty four hour period. Where you place your thermometer is often overlooked, but very important. The idea is to capture ambient air temperature. So the ideal place is half way up your grow room and out of direct light. If the air in your grow room is well mixed with the use of oscillating fans, your thermometer will be reading an accurate temperature.

Consequences of high temperature

Small pores on the leaves (stomata) allow water vapour and gasses to leave the leaf and keep the plant cool (transpiration). If your plants are within their temperature comfort zone (72-82F) and are transpiring healthily, theyll keep themselves up to 4F cooler than the ambient air temperature.

As a defence mechanism to conserve water, your plants stomata will start to close at around 85F (at ambient CO2 levels ~390ppm). With the stomata shut, your plants will not be able to transpire to keep themselves cool. If the temperature remains too high, the water trapped in your plants leaves can overheat causing internal cell and enzyme damage. The result is poor growth and unhealthy plants.

If the temperature in your grow room is too high, your plants will respond in a few ways. Theyll appear stretched as the inter-node distance increases with a high temperature. This results in very airy flowers or poor fruit quality. During high temperatures, your plants will have difficultly laying down dense material because their sugar energy is being used so fast that they cut back on the energy used to make flowers and fruit.

High heat is often associated with summer and low humidity in grow rooms. As a result, the roots of plants take more water than nutrient salts to compensate for the loss of water from the leaf due to high transpiration. This increases the nutrient strength in your reservoir or media leading to nutrient lockout, which can cause over-fertilization.

Controlling Temperature

To keep the growing environment within your plants comfort zone you must remove the hot air from your grow room. Using an inline extractor fan you can take hot air and duct it out of the room. Due to heat rising, you should place your extractor fan at the top of your room.

The lights in your room are the main heat generators, so the more lights you have, the larger your fan will have to be.

As well as removing the hot air, you also need to supply the room with fresh cooler air. This can be done by using another inline fan to pump fresh, C0 rich air into your room. Relying on one extractor to take the wasted air out and draw the air in through vents is not as effective in bringing temperatures down.

For effective temperature control, we recommend that you use ventilation system with a thermostatic fan speed controller. With these devices you set the desired maximum temp (around 82F). If the room temperature exceeds this, the fans adjust their speed to move more air, as the temperature decreases, so do the fans speed. Thermostatic fan speed controllers are excellent for summers where the outside temperature varies greatly from day to day.

Heat can often build up in your room under the lights. Its important that you have good air exchange and keep the air well mixed to avoid heat build-up. This can be done using a pedestal fan to move the air around from under the lights. Heat shields are also a good way to avoid a high temperature under lights and are especially good for rooms with low ceilings as they disperse heat very well.

An efficient way of removing heat from your lights is to use an enclosed air cooled reflector, or with glass cool shade reflectors. Air and heat is pushed through these reflectors using an extractor fan. Air cooled reflectors are very efficient and are commonly used to remove heat from the grow lights in summer running grow rooms. If heat becomes an issue for you, the use of air cooled reflectors can bring room temperature down significantly.

The time of day your lights come on can also have a big effect on your grow room temperature. In the hotter months, its advisable that you start the light cycle in the evening, running the lights through the night. This allows you to bring in cooler night time air into your room during the light cycle and avoids extreme mid-day temperatures. (Running your lights through the night is great in winter also, counteracting extreme low temperatures outside at night).

If your grow room temperature is constantly high and growth is affected, you may want to invest in an air conditioner. Air conditioners are the most effective way to reduce high temperatures in the hotter months. They also remove water from the air, thus lowering humidity, so a humidifier may also be needed when using air conditioners.

If your temperature is high and humidity is low, the use of a humidifier may be enough to increase humidity and lower temperatures. Increasing the humidity has a cooling effect and can bring the temperature down by as much as 5F.

The last resort for a high temperature is to simply cut back on the number of lights in your room, or if you have dimmable ballast you can reduce the wattage. If you have two 600W lights and are finding that your day time temperature is constantly above 85F and your plants are struggling, youll get a poor yield and poor quality produce. By cutting back to one 600W light, or by turning both down to the 400W setting, the temperature will drop to a manageable level and your plants will remain healthy. Obviously, thisll drop yield, but it will allow you to grow better quality produce.

Roots and temperature

If roots are to function efficiently and take up the nutrients, they need to be kept at a good temperature 24 hours a day. For established plants with a good root mass, the temperature around the root zone (rhizosphere) should be 65-75F. High root temperatures can increase the risk of root disease and lower the dissolved oxygen content of the nutrient solution. Roots with temperature below 68F will have a weaker ability to take up nutrients. When growing in pots/containers, temperature around the roots can be increased using warming mats/pads. For people using re-circulating NFT systems, its better to keep the solution nearer to 70F because a higher temperature will increase the risk of pathogens. This can be done with the use of a water heater. If your water temperature is too high, you can reduce the temperature with a nutrient chillier, capable of lowering the nutrient solution temperature by 10F.

Day Time and Night Time Temperatures

Plants are very sensitive to differences in temperature between the light cycle and dark cycle. As mentioned earlier, to measure the night and day temperature you need a max-min thermometer. If you want fast vegetative growth, you need to try and keep your night and day temperatures as close as possible. However, to promote flowering and fruiting, you need to increase the difference between night and day by approx. 10F (day). If your temperature differential is bigger than 20F, youll put your plant under stress.

The sugars your plants have made during the light cycle will be poorly transported in the dark cycle, thus lowering growth rates. To keep night time temperature up, use an electric fan heater or an oil filled radiator during the night cycle.

GROW ROOM VENTILATION

Good ventilation is essential for healthy plant growth. In fact, it is one of the most important factors you need to consider when growing, because if there is not enough ventilation in your grow room, your plants will struggle to live. Read on to learn more about ventilation.

Ventilation is about controlling the quality of air, CO, heat and humidity in the grow room. To achieve a high quality of air in your grow room, you need to ensure that there is a sufficient amount of air exchange. The amount of air exchange required will vary according to the temperature outside. But as a general rule, maximum winter ventilation rates rarely exceed 12-20 air changes per hour; however, maximum summer air exchange rates can go up to 60 air changes per hour.

To achieve sufficient air exchange, we recommend that you purchase a good extractor fan. Basically, an extractor fan will help you to achieve the ideal growing environment in your grow room. By circulating and exchanging air, an extractor fan will give you a greater degree of control over the following:

Heat

One of the main functions of an extractor fan is to remove heat that accumulates rapidly in indoor growing situations. Ideally, the temperature in your grow room should range between 22-28C when the lights are on. You should aim to reduce this temperature by 5C at night. You may seriously damage the health of your plants if you allow the temperature to exceed or drop below this range.

Dr Greens Tip:

A heater is essential to keep the temperature around 20C during cold winter nights.

Humidity

You should aim for 50-75% humidity in your grow room when your lights are on. A high temperature and too much air flow can both affect the relative humidity (RH) in a grow room. Generally, when growing indoors, a high temperature lowers humidity – creating a poor environment for plant growth. This is a common problem in summer, so additional moisture may need to be introduced via a humidification system.

Dr Greens Tip:

Continually check the humidity level of your grow room with a hygrometer.

If humidity in your grow room drops very low (below 40%), it may cause the young leaves of your plants to become smaller, whilst older leaves may simply curl at the margins, appear burnt and drop off. It is important to note that such stresses tend to stunt plant growth. This is more apparent when plants are very young. Large, mature plants naturally raise humidity.

Dr Greens Tip:

Use a humidifier when the humidity level in your grow room is too low.

During the winter months, you are more likely to need an extractor fan to replace fresh CO rich air and for dehumidification (removing moisture), rather than reducing temperature. Grow room air is not exchanged as frequently in winter, and this enables plants to naturally maintain higher grow room humidity without the air being exhausted.

Dr Greens Tip:

A ventilation fan helps to promote healthy growth by constantly replenishing air.

However, too much humidity can create a perfect environment for fungal diseases. Your plants are particularly vulnerable when you switch your lights off and the temperatures drop when the humidity increases. In fact, inadequate ventilation is the root cause of most fungal diseases; where fungal spores thrive in humid, stagnant air and jeopardise entire crops. But if you keep fresh air flowing, then mould can be a thing of the past!

C0

Good ventilation greatly aids CO, which is vital for photosynthesis. In fact, photosynthesis will not take place without CO. Remember, photosynthesis is the process by which all plants make food – the key ingredient for healthy growth.

Dr Greens Tip:

An intake fan will bring fresh CO rich air into your grow room.

Air Circulation

Installing an additional air circulator in your grow room is one way of achieving a more even distribution of carbon dioxide, humidity and temperature – especially during the winter months. We, therefore, advise you to use an air circulation fan with your ventilation system. This will encourage the cold air brought in by your ventilation system to mix evenly with the warm inside air. Circulating fans are relatively inexpensive to operate, and are located to move air along the length of the grow room.

Fans

There are many different types of fans available, but here we talk in-depth about the extractor fan. We also touch upon other equipment you can use to improve ventilation.

Extractor fan

The extractor fan is the most critical fan in the growing area. It is capable of removing heat and moisture from the grow room. Remember, both heat and moisture accumulate rapidly in indoor growing situations.

Dr Greens Tip:

An extractor fan is also known as an exhaust or ventilation fan.

However, you must make sure you have the correct size fan to get the most out it. Most growers also require a ventilation system capable of dealing with outside summer temperatures. To determine the exhaust (supply air flow) rate in m3/hr, simply multiply the volume of the room (m3) by 60.

Example:
1.Volume of grow tent = 2.4 X 2.4 X 2 = 11.52m3
2.Required air flow rate = 11.52 X 60 = 691m3/h

A ventilation fan that is equal to or greater than 691m3/h is required for the exhaust. Most growers will use a carbon filter on their extraction fan to remove any odours. A carbon filter can reduce the flow rate of a fan by up to 25%, so we should multiply this figure by 1.33 to allow for this reduction. 691 X 1.33 = 921m3/h

So, a ventilation fan that equals or is greater than 921m3/h is required for the exhaust fan to be used with a carbon filter. In this example, an RVK 200 L1 – which has a max air flow of 983m3/hr – would be required.

After determining your m3/hr requirements, you will need to establish your intake requirements.

As a rule of thumb, a free area measuring 0.09m2 is required for every 1000m3/hr of exhaust. Air grilles will restrict air flow as they have a free area of around 60%; For example – a 250mm square grille will have a face area of 0.25m x 0.25m = 0.0625m2. 60% of 0.0625 = 0.0375m2 free area. This means that this 250mm x 250mm grille will provide air replacement for the rate of .0375/0.09 x 1000 = 417m3/h.

Following our example above, using a RVK 200 L1 with a carbon filter as an exhaust it will be moving 737m3/hr, so for adequate air supply it will need a minimum of 2 x 250mm square vents with grilles, or 1 x 260mm square vent without a grille. Using openings to allow the extractor fan to pull fresh air in is referred to as passive ventilation.

However, it is often not feasible to have openings for intake air. We recommend that you use an intake fan as well as an extractor fan. An intake fan is, quite simply, an extractor fan turned around so that it forces air in (rather than expelling it outside). This is referred to as active ventilation.

When sizing an intake fan you should input 15% less than the actual air flow rate to maintain a negative air pressure. This ensures all air departs the room through the carbon filter. Follow the steps below to work out your intake fan size.

Example:
1.Extractor fan max airflow x 0.75, this 25% reduction is for a fan with a carbon filter.
2.Following on from the example above: RVK 200 L1 983m3/hr x 0.75 = 737m3/hr
3.Take the reduced airflow figure and reduce it by a further 15% by multiplying by 0.85.
4.737 x 0.85 = 626m3/hr

So, a ventilation fan that is close to 626m3/hr is required for the intake fan. In this example, an RVK150 L1 – which has a max air flow of 666m3/hr – would be required. If the intake fan requires the use of a long length of ducting, or ducting with bends, it would be better to use a RVK200A1 with an air flow of 778m3/hr.

Note – When bringing cold air into your grow room, it is important to ensure that there is proper mixing with the main mass of grow room air. This will help minimise any negative effects of cold air contacting your plants.

Other ways to improve ventilation:
1.You can reduce ventilation requirements by making some small modifications to your grow room. For example, using air cooled lights will help to prevent heat generated by H.I.D lighting from entering your grow room. They’ll also reduce “hotspots”, allowing for closer light to plant tolerances. Your plants will also be able to use C02 much more efficiently.
2.Position your intake fan low down, diagonally opposite the extractor. Remember, you should mount your extractor high up. This will allow a fresh current of cool air to flow across your grow room, whilst removing any hot, humid air at the same time. When mounting your fans, use the proper brackets to avoid excess vibration.
3.To achieve accurate climate control in hot and cold weather it is worth investing in a temperature regulated fan speed controller. Regular air changes are critical for good growth; however, fans on full power can create noise problems. A combined fan speed controller and thermostat will allow you to regulate the number of air changes per hour. It will also compensate for hot and cold weather by increasing or decreasing the air flow if necessary. Fans will run at a reduced speed continuously, only firing up to full speed when triggered by the thermostat.
4.If noise is a major concern, consider using insulated (acoustic) ducting. This can remove up to about a third of the noise generated by air turbulence. It is necessary to use at least one metre on both ends of the fan to get the full benefits. Using silencers is also a good way to reduce noise. They can make it possible to run a ventilation system in a small domestic setting, very useful indeed when you have a lot of lights running. Again, for full effect, fix a silencer on each end of your fan. This will help to reduce noise levels by up to a third.
5.Certain types of crop can cause bad odour. In a domestic setting, the scent of your vibrant crop of garlic may smell wonderful to you, but your guests may think differently! A professional carbon filter attached to the exhaust fan will help you to achieve 90-95% odour removal, meaning that just about any crop can be grown without comment.

(Note – it is important to match the correct carbon filter to your extractor fan. A 750m3/hr capacity extractor fan needs to be matched with a carbon filter capable of treating 750m3/hr of air or more. Do not try to use a lower capacity filter, it may be able to treat the odours but it will significantly reduce the efficiency of the extractor fan, resulting in high grow room temperatures and a short life expectancy for the fan.)

COOLING GUIDE

When the temperature rises outside, so does your grow room temperatures with potentially damaging consequences. Flowers become loose, fruits can abort and yields can be significantly reduced. Maintenance of your grow room operation becomes more intense as the plants consume more water through transpiration to cool the leaf temperatures down. Nutrients become toxic because this increased transpiration drives nutrient uptake. The first symptom of toxicity usually leads to yellowing of the middle-aged to larger leaves just below the flowering tops. All this leads to growers looking miserable on hot, sunny days rather than enjoying it.

If you also want to inject with carbon dioxide, then the only efficient, controllable way to achieve this is to use air conditioning. In order to put a smile back on your face on those hot sunny days or indeed those cold cloudy days where you want to inject with carbon dioxide but you still cannot have the exhaust fans off for any length of time then Aquaculture is pleased to offer advice on using air conditioners.

To help you decide which cooling product best suits your needs, heres a rough guide below:

Permanent air conditioners that require professional installation are usually not suitable for grow rooms, but portable units are. There are 2 types of portable air conditioners, mono-blocks and portable split units.

Mono-blocks are an all in one unit that have an exhaust hose, air is pulled into the unit while cool air is blown out the top and hot waste air is blown out the exhaust hose. These can be used inside grow rooms, but if your crop has a strong odour this will also be blown out the exhaust hose. Mono-block air conditioners are best used outside grow rooms, this cooler air can then be pumped into the grow room via an inline fan.

Portable split air conditioners have an outside unit and an inside unit. The outside unit processes the air and pumps refrigerant to the inside unit which blows out cool air. The inside unit can be placed inside the grow room without the risk of odours being pumped out of the air conditioner.

How do I calculate my air conditioning requirements?

Simple! – Grab a calculator and follow the simple instructions

  • Multiply the length by the width by the height of the room to be air-conditioned which will give you the cubic capacity
  • If you are measuring in feet then multiply the cubic capacity by 5 which will determine your Btu requirements. If you are measuring in metres, then simply multiply the cubic metres by 175.

Example: Room dimensions are 25ft x 12ft x 8ft = 2,400 cubic feet. (Multiply by 5 giving 12,000 Btu’s)

Example: Room dimensions are 7.6m x 3.7m x 2.5m = 70.3 cubic metres. (Multiply by 175 = 11,810 Btu’s)

The above calculations assume a grow room with no lighting or other heat sources.

For every lighting system, add the following Btu amount onto the above calculation.

  • 250W Sodium/Metal Halide Lighting System, add 640 Btu’s
  • 400W Sodium/Metal Halide Lighting System, add 1020 Btu’s
  • 600W Sodium/Metal Halide Lighting System, add 1530 Btu’s
  • 1000W Sodium/Metal Halide Lighting System, add 2560 Btu’s

Example: Room dimensions are 3 metres by 3 metres by 2.5 meters = 22.5 cubic metres.

In that volume I have 4 separate 600W sodium lighting systems.

Easy then, this is what we do:
1. From the above example, 22.5 cubic metres multiplied by 175 = 3940 Btu’s
2. Multiply 4 (no. of lights) by 1530 (cooling for 600W light) = 6120
3. Add 3940 to 6120 = 10060 Btu’s of cooling.

If you have a south(ish) facing grow room or an attic then multiply the total Btu requirement by 1.5. If you are in any doubt about your calculations our sales staff will be happy to talk you through.

Do Portable Air Conditioners require installation?

The mono-block air conditioners do not need any special installation other than placing the exhaust in a suitable location to vent away the hot waste air then just switch on!

For the portable split air conditioners, there is no exhaust hose. The umbilical cord links the inside and outside units, and contains R407C cooling refrigerant. The umbilical cord comes attached and ready to use, if you need to detach the cord for installation you will need to re-gas the unit with refrigerant. Please note: different AC units are filled with different types of gas which can be damaging to the environment and to human health, any type of AC re-gassing should be done by a trained professional.

Are there any special requirements for the use of Portable Air Conditioning?

Yes. Access to an open window, vent, external door or suspended ceiling is essential in order to position the outside unit for split AC units types, or duct the hot air exhaust from mono-block AC units.

The air conditioner needs to be positioned within reach of a 13-amp 230V socket and located in a manner to avoid any obstruction to the airflow.

Always ensure that the electrical supply to the unit is adequate and not limited by the other electrical consuming products in your grow room.

Where do I position my Air Conditioning Unit?

You obviously do not want to position the air conditioner unit next to the extractor fan. We have included a little diagram below to help you decide on a suitable position. The air conditioner should be located at one end of the room, usually at the opposite end from the exhaust fan. If you are using an intake fan as well, the unit should be located close to this to achieve a greater cooling capacity.

UNDERSTANDING RELATIVE HUMIDITY

Relative humidity (RH) is often overlooked when growing indoors. However, if you want strong healthy plants, you need to consider the relative humidity of your grow room. Here we explain what you need to know….

What is RH and why is it important?

RH is the amount of water vapour in the air compared to how much moisture the air could possibly hold at that temperature. Plant growth is influenced by RH because it directly affects the amount of water your plants move through their stems and leaves – essential for keeping plants hydrated and transporting vital nutrients.

What should the level of RH be in my grow room?

For healthy plant growth, you should aim for RH of 50-70% (RH can be measured using a hygrometer).

What are the consequences if the RH in my grow room is too high?

When RH levels are too high in your grow room, you have the perfect environment for spores to germinate and fungi to grow. The most common type of mould you will encounter is Botrytis (bud rot). Others include leaf moulds, such as Powdery Mildew. There is also a risk of stem infections, although these are less common.

Hint: a lack of adequate ventilation can often be a cause for excessive RH. Please refer to our ventliation article for information on how to solve such problems. If ventilation is not an issue, a quick and easy way to lower humidity is to use a dehumidifier. An air conditioning unit during the summer that expels cool, dry air, will also help reduce RH.

What are the consequences if the RH in my grow room is too low?

When your grow room is suffering from low amounts of RH, the leaves of your plants begin to curl upwards at the margins; looking like a tube/straw. The low RH decreases the amount of transpiration as less leaf surface is exposed to dry air, which lowers the amount of water your plants will lose.

Generally, low RH tends to be more common than high RH. In fact, when growing indoors under hot lights, most hydroponic growers tend to start off with very low RH. This is problematic because RH needs to be relatively high during the vegetative growth stages.

Example of a low humidity problem:
When you start out, your plants will be small with not much vegetation. The grow light(s) will also heat and dry the air in the grow room; giving a RH level of 35-50% and temperature of 25-28C. This will cause the small plants to take up and release increased amounts of water to balance water vapour in the air. This stresses the plants considerably by taking away the energy it needs to produce new roots, shoots and leaves. But if you increase the RH levels up to 60-70% during these vital, early stages, you will ensure quicker establishment of roots, vigorous growth and compact internodes. Ultimately, your plants will grow faster and healthier.

Once the plants have grown in size and have produced more shoots and leaves, they will take up more water into their roots and lose more water vapour from their leaves. As there is more water vapour being released into the air by the plant, the humidifier can now be switched off.

If the RH in your grow room falls back below 40%, you will experience a lot of problems – one of them being over-fertilisation. High temperatures and low RH will cause your plants to take up and release more water. Whilst your plants are taking up more water, they will take up less nutrient – causing the nutrient to continually increase in strength. It is this increase in nutrient strength – coupled with an increase in water uptake and release – that causes over-fertilisation of your plants and other nutrient related problems.

The link between RH and temperature is the cause of many problems during the summer months, but despite this, it is still one of the first things that is overlooked.

Humidity and the Dark Cycle

Some indoor growers find that when the lights go out, RH shoots up. This leads to mould problems like Botrytis on fruits or flowers if the night time humidity is too high. This can be corrected by using a dehumidifier. Be sure that the dehumidifier does not remove too much water during this time, as it can over-dry the air; causing the plant to lose water through its leaf tips. This water can then collect on the leaves, creating the perfect micro environment for spore germination. Ideally, you want your grow room to have a lower humidity during the day compared to the night. The ideal figures to aim at during fruit/flower formation would be 50-60% in the light cycle, and 60-70% during the dark cycle.

Humidity and Propagation

During the propagation stages (rooting cuttings or germinating seedlings) RH is controlled and kept high using a propagator – such as the Stewart Heat and Grow Electric propagator. We recommended that you spray the lid of your propagator daily to keep the humidity above 80%. This will minimise water loss through the plant and concentrate its energy on producing new roots.

In summary, you will achieve the best results with your plants if you keep humidity above 50% and below 70%, and ensure RH is not lower in the night than day.

CONTROLLING TRANSPIRATION IN THE GROW ROOM

Relative humidity is still the most commonly used measurement for grow room control, even though it is not a perfect indication of what the plants feel. Plants respond to the difference between humidity levels at the leaf stomata and the humidity levels of the surrounding air. At the same relative humidity levels, but at different temperatures, the transpiration demand for water from the leaves can double. Therefore, another kind of measurement, called Vapour Pressure Deficit is often used to measure plant/air moisture relationships. VPD is defined as the difference in the amount of water in the leaf (always assumed to be 100% RH) and the humidity of the outside air is the VPD. The higher the VPD, the greater the evaporation rate.

Role of Humidity

The main plant mechanism for coping with humidity is the adjustment of the leaf stomata. Stomata open and close in response to vapour pressure deficit, opening wider as humidity increases. When humidity levels drop the stomata can close to about 50% to help guard against wilting. This also reduces the exchange of CO2, thereby affecting photosynthesis.

Transpiration – Plants can control their rate of water loss. Because the leaf stomata have an ability to limit transpiration rates, a doubling of the moisture deficit may result in only a 15% increase in the transpiration rate. However, when humidity levels are very high, the total uptake of minerals is reduced since plants are unable to evaporate enough water.

Photosynthesis – Humidity levels indirectly affect the rate of photosynthesis because CO2 is absorbed through the stomatal openings. At higher daytime humidity levels, the stomata are fully opened allowing more CO2 to be absorbed for photosynthesis.

Growth and Quality – Most grow room plants tend to grow better at higher relative humidity. However, mineral deficiencies, disease outbreaks, smaller root systems, and softer growth are possible consequences of excess humidity.

Quality Problems Due to Humidity

Too Low- Dry Tip Burn, Wilting, Small Leaves, Stunted Plants, Spider Mites, Leaf Curl.

Too High- Oedema, Edge Burn (Guttation), Soft Growth, Mineral Deficiencies, Disease Outbreaks.

CARBON DIOXIDE

Overlooked by many growers, carbon dioxide is vital for healthy plant growth. In fact, maintaining optimum levels of Carbon dioxide can significantly improve the yield of your plants. Read on to learn how you can use Carbon dioxide to get the best results from your plants.

What is carbon dioxide and how is it measured?

Carbon dioxide is a natural gas present in our atmosphere. It is measured in parts per million (ppm). In the atmosphere there is about 300 – 400ppm of carbon dioxide.

Why is carbon dioxide so important?

Without carbon dioxide your plants will not grow. This is because it is essential for photosynthesis the process by which your plants use light, water, and carbon dioxide to make glucose (plant food). Your plants need glucose for healthy growth.

Photosynthesis can only take place in the light period. This is when the leaves of your plants absorb carbon dioxide and give out oxygen. During the hours of darkness, the leaves give off carbon dioxide and absorb oxygen.

During higher temperatures and light levels, the absorption of carbon dioxide and the rate of photosynthesis will also increase until a maximum is reached. Most growers are aware that optimum light and temperature can enhance plant growth (you may want to refer to our Lighting and Temperature articles). However, even if optimum light and temperature are achieved, a lack of carbon dioxide can be a limiting factor which means you will not get the best results from your plants.

It is important to be aware that if temperature exceeds 32C, the stomata (breathing holes) of your plants will close. Consequently, your plants will not absorb carbon dioxide, which means they will not grow. Like most growers, you will probably be using an extractor fan or a cooling system to keep the temperature at an optimum. If so, you will need to switch the extractor/cooling system off whilst adding the carbon dioxide to prevent it from being extracted before your plants absorb it. This will have an influence on injection times, which is explained towards the end of the article.

Carbon Dioxide in my grow room

As mentioned, there is approximately 300-400ppm of carbon dioxide in the atmosphere. However, whatever carbon dioxide that is present, will not last long in a tight grow room with little to no ventilation. A lack of carbon dioxide will prevent your plants from photosynthesising, and eventually stop growing. To avoid such a situation, you need to ensure that there is an adequate amount of ventilation in your grow room (please refer to our Ventilation article for more info).

It is possible to speed up the photosynthesis process by increasing the level of carbon dioxide to 1000-2000ppm during the light period. This will enhance the overall development and yield of your plants.

Dr Greens Tip:
If you are adding carbon dioxide to your grow room, always use an oscillating fan to ensure it is well mixed.

How do I know how much carbon dioxide I need to give my plants?

When adding carbon dioxide, you need to consider the size of your grow room. The simple calculation/example below will help you to decide how much carbon dioxide to add to your grow room.

1. Work out the capacity of your growing area in m:

  • Length (m) x Width (m) x Height (m)
  • For example, 3m x 3m x 2.5m = 22.5m

2. Calculate the desired level of carbon dioxide (this example works on 1500ppm):

  • Background level (approx amount in atmosphere) of carbon dioxide = 350ppm
  • Desired level = 1500ppm

3. You now need to calculate the increase required:

  • Desired level Background level = Enrichment level
  • 1500-350 = 1150ppm (=0.000115)

4. You now need to calculate the volume of carbon dioxide required:

  • Capacity of your grow room x Enrichment level = Volume of carbon dioxide to be added
  • 22.5 x 0.00115 = 0.026m

5. There are 1000L in 1m (so you need to multiply 0.026 by 1000 to give you the volume in litres)

  • 0.026×1000 = 26L

This means that 26L of carbon dioxide is required per injection to raise it to the desired level.

The timed injection is up to you, however; shorter injection cycles are preferable to longer cycles.

For example, 26L of carbon dioxide means you would release 13L per minute for 2 minutes. You would then dose again 1-2 hours later.

Shorter injection cycles are better because carbon dioxide is available to your plants more often. It also means that you will not need to have your extractor fan/cooling system off for long periods of time.

Dr Greens Tip:
There are controllers available with C0 sensors that monitor the growing environment to ensure there is an optimum amount of carbon dioxide in your grow room.

When should I add carbon dioxide?

We would recommend that you start adding carbon dioxide as soon as you put your plants into your chosen hydroponic system. You should continue adding carbon dioxide up until harvest. Never suddenly remove the extra carbon dioxide you are supplying to your plants. This can have an adverse effect on your plants overall development.

CARBON FILTERS

Carbon filtering is a method of filtering that uses a bed of activated carbon to remove contaminants and impurities, using chemical adsorption.

Each particle/granule of carbon provides a large surface area/pore structure, allowing contaminants the maximum possible exposure to the active sites within the filter media.

Activated carbon works via a process called adsorption, whereby pollutant molecules in the fluid to be treated are trapped inside the pore structure of the carbon substrate.

There are 3 types of carbon used for air filtration; Pelletized, Coconut and Granulated.

Pelletized Carbon

This carbon is produced by burning coal and processing it into tiny rods. These are then broken up and distributed through the filter. This method is probably the worst carbon to use in air filtration. The process of creating the pelletized carbon involves the carbon being crushed into pencil like structures then bonding agents are added to hold the pellet together. This collapses the pores structure which in turn makes the carbon less effective as the organic microbes cannot be absorbed by the carbon. Because of the small pores size of the pelletized carbon, it will only be re activated to about 50% or less which in turn affects the absorption rate. Pelletized carbon also contains a large percentage of ash, which is a dead material within the carbon and offers no benefit to the user.

Coconut Carbon

This is produced by burning coconut fibres. This produces carbon with a greater surface area than coal, but with much higher ash content and higher moisture levels. Coconut carbon carries around 20% ash with a 5% moisture level, this high moisture level detracts from the overall adsorption of the filter. This carbon only has about a 12 month life span and is very ineffective.

Granulated Carbon

Most granulated carbon is produced by burning coal but it is left unprocessed, this gives you the virgin granulated carbon used in high end filters such as Mountain Air and Rhino. This carbon has very low ash content, less than 13%

LIGHTING

IS YOUR BALLAST REALLY 600W?

Recent industry research has revealed that there are many magnetic ballasts on the market that do not provide the correct power to your lamp for them to perform properly. This is a result of poor manufacturing and the use of substandard components to save on production costs. The quality of your HID ballast also means the difference between a safe lighting system or a dangerous one with the potential to cause a fire.

Genuine Quality Ballasts

Light is the key ingredient in the growing environment that determines how well a plant grows. High intensity discharge lighting is still proven to be the most efficient method of plant lighting, with high power ranging from 150W up to 1000W. The 600W magnetic HID ballast system is the most popular choice for growers that are vegetating their plants through to the fruiting/flowering stage due to the efficiency at which it converts power (watts) in to quality growth light known as PAR (Photosynthetically Active Radiation). As a result there is a wide variety of magnetic ballasts available on the market and new brands emerging all the time.
Recent industry research on all new 600W magnetic ballasts on the market revealed that many of these ballasts do not deliver 600W to the lamp. This is a major quality issue, as all major lamp manufacturers design their lamps to run at a certain power. Therefore if you do not deliver the correct power to your lamp it will not operate correctly and the efficiency will dramatically decrease. A properly performing 600W ballast can deliver up to 33% more light than an underperforming 600W ballast. The loss in power from an underperforming ballast has a detrimental effect on plant growth and overall yield.

Why are so many ballasts underperforming?

In order to appear better value, some manufacturers are cutting corners in everything from design and build to the sourcing of cheaper, less reliable components. Many from outside of Europe are not obliged to meet the same standards of quality control or even to meet the higher mandatory standards that protect European consumers. The result is a proliferation of poorly manufactured and less reliable ballasts that deliver far less power than they advertise.

Effects of underpowering HID lamps:

  • Substantially less Photosynthetically Active Radiation essential for plant growth
  • Reduced Colour Rendering Index (CRI) the ability of the lamp to produce the full colour spectrum of light required for plants to grow.
  • Less power efficiency (less light output per watt consumed).
  • Frequent lamp changes (from erroneously blaming the lamp for the poor performance!)

Genuine Quality Standards

Supplies correct power to the lamp (BS EN 60923)

The ballast should provide the correct power to the lamp to within +/-3%. For example, a 600W magnetic ballast must consume approx. 655W in order for 600W of power to reach the lamp. This is to allow for 55W that is lost mainly as heat in the ballast before it reaches the lamp.

Grade 2 winding wire (BS EN60317-1)

A ballast is an inductor made of copper or aluminium windings. Winding wire comes in Grade 1 and Grade 2. Grade 1 only has a single coating of insulating resin. Genuine Quality ballasts use grade 2 meaning it is has two coats of insulating resin for thermal and electrical durability.

Precision winding

Precision winding means every turn and layer of winding wire is precisely wound so as each wire is perfectly in line and parallel to its neighbour. Low cost ballasts commonly use scramble wound coils. Precision winding is a slower and more expensive process that near eliminates the possibility of breakdown between winding wires.

Matched timed igniter (BS EN 61347-1) (BS EN 61347-2-1)

Igniters should be matched to the ballast and ideally should be timed to protect the ballast in the event of a lamp failure. If the igniter is not timed, in the event of a lamp failure the igniter will continue to try and ignite the lamp until the unit is switched off. This puts the ballast under a lot of strain due to the high igniter pulse voltage that can quickly degrade a ballast.

Capacitor with Power Factor Correction (PFC) (BS EN 61000-2-3)

Capacitors should meet European specifications with a suitable power factor as close to 1 (unity) as possible. Low cost capacitors have a lower power factor meaning they draw wastefully high currents from the supply.

Vacuum impregnation with resin � Class H (180C) insulation

Epoxy-polyester resin coating protects the ballast and provides insulation. Genuine Quality ballasts use vacuum impregnation to completely seal all areas with no gaps for insulation properties that are second to none giving complete protection.

INDOOR GROW LIGHTS

Light is one of the most important factors to consider when growing plants. It is very simple – no light means no growth. In fact, as a general rule, the more light your plants have access to, the quicker they will grow and the more they will yield. The benefit of an indoor grow light is that it allows you to grow literally any plant, anywhere, anytime! However, to get the best out of your indoor grow light and growing it is helpful to understand the basic principles of light.

Spectrum

Anyone who has seen a rainbow will know that sunlight is made up of different colours. These colours of light can also be differentiated by their wavelength which is measured in nanometers (nm).

The human eye is most sensitive to light around the middle of the visible spectrum – between 500 and 600nm. Plants find wavelengths between 400 and 700nm useful for turning light into energy (photosynthesis), and this area is referred to as Photosythetically Active Radiation commonly abbreviated to PAR. While the human eye finds light at 555nm the most visible (thus more useful), plants find two distinct areas of the spectrum most useful the blue area between 400-460nm and the red area between 580-700nm.

Measuring Light

Lumens is a measurement of light intensity, and is often used to define the output from artificial lights. This is fine for lights to help us see in the dark, but becomes rather useless when measuring horticultural grow lights because lumens are measured according to what the eye is sensitive to. Using lumens is therefore not a correct representation of the properties of a lamp that are useful to plants.

Lux is often used by light-measuring devices and is simply a measurement of how many lumens fall on each square meter of surface. So an illumination of 50,000 lux is 50,000 lumens falling on each square meter. Lux measurements are useful for measuring intensity from grow lamps and can be used to determine an accurate height to position the light above the plants, or to check for lamp degradation. However, lux is still not a good measurement for determining the quality of light and how good it is for growing plants.

Professional growers and light manufacturers have switched from measuring light in lumens and lux, to photon count in the PAR area. Without going into too much detail, a photon is a particle of light. A blue photon has a short wavelength and does not have as much energy as a red photon – which has a long wavelength. The plant, however, is only interested in the number of photons (it does not use the energy in the photon for photosynthesis). A plant requires 8-10 photons to bind one molecule of CO2. So a blue 600W light produces less photons than a red 600W light and is less efficient for photosynthesis. However, you do need more than just red colours in your spectrum for a plant to grow healthily.

A device to measure photons is called a quantum meter. The total amount of photons – known as the photosynthetic photon flux (PPF) – from a lamp can be measured with a quantum meter to give you accurate data on the amount of photons per second coming from your lamp. Photons are counted in micromoles (mol) and in case you are interested, one mol is 602214150000000000 photons! The unit used for PPF is micromole/second (mol/s), and a good 600W HPS lamp will emit 1100 mol/s.

To summarise, if you have two lights and one has a higher lumen output, it is not an indication that it is better for growing plants. The most useful light output data is plant useable light measured in micromoles.

Day Length

The amount of light your plant receives in a 24 hour period is called the photoperiod or day length. Some plants use the photoperiod as a signal to know when to produce leaves, flowers or fruit. Using this signalling tool, indoor growers can alter the photoperiod using timers to control their lights and their plants. Long day lengths of 16-24 hours are most commonly used for vegetative growth, and short light cycles of 12 hours are used for flowering or fruiting. Most grow lights are too powerful for plug in timers, the solution to this this will be covered later.

Light and Environment

All lights produce some heat as well as light. When growing indoors this heat generated by the grow lights need to be removed using an extractor fan to keep the plants growing environment comfortable. If you position your light too close to your plants, the heat from the lamp may burn them. So, it is very important to correctly hang your growing lights.

Types of Grow Lights

There are two categories of lights commonly used for growing plants. These are fluorescent and high intensity discharge (HID).

Fluorescent Grow Lights

Fluorescent grow lights are more suitable for propagation and vegetative growth. They have good colour rendering properties (a high proportion of the light emitted is used by the plant) and produce less heat than HID grow lights (see below). This allows them to be placed closer to your plants to make the most of their output.

There are two types of fluorescent lights used for growing – Compact Fluorescent Lamps (CFL) and T5 lamps (aka tubes). CFLs are large energy saving lamps and have the electronics to ignite the lamp at their base. These can be screwed into a reflector or simply hung vertically above the crop. T-5s are the most efficient fluorescent tube light, and need separate electronics to ignite the lamps. These electronics are housed within T5 reflectors. Due to the size of the T5 tubes, they produce a very uniform level of light over a larger area in comparison to CFLs.

Compact Fluorescents are available in 150W and 250W, as well as a propagation lighting system utilising 2 x 55W PL lamps. T5s are available as 2ft 24W lamps and 4ft 54W lamps. These are available individually without a reflector or as an integrated lighting system with two, four or eight lamps.

Fluorescent lights are great for seedlings and cuttings, as plants at this stage do not need intense light. Both CFL and T5 are low intensity, so they need to be placed close to plants to be effective at promoting growth. If using fluorescent lights above propagators, do not place them too close as this will cause the internal propagator temperature to get too high.

The light emitted from a fluorescent lamp can vary depending on the lamp colour. Fluorescent lamps come in different colour variations differentiated by the Kelvin colour temperature scale. The Kelvin scale has become industry standard for differentiating commercial and domestic lighting, but is rarely referred to in horticultural lighting other than for fluorescent lamps.

Fluorescent lamps with a high Kelvin are mainly used for propagation or vegetative growth; these usually come in around 6400K. Lamps with a low Kelvin are used for flowering and usually emit light around 2700K. A mixture of both (1 x 27K for every 3 x 64K) is a good approach for vegetative growth , and the reverse (3 x 27K for every 1 x 64K) fruiting or flowering.

Top Tips:

  • Due to their lower light output, fluorescent grow lights should not be used instead of HID lights during the flowering stage. However, they are effective as supplementary lighting when hung in between your plants with CFL lamp hangers, or as side lighting with T5s.
  • All of our fluorescent lights can be plugged into a timer to control the photoperiod. A relay or contactor is not necessary.

HID Grow Lights

HID (High Intensity Discharge) lighting is the most efficient way to convert electricity into light and is the most popular type of horticultural grow light. HID grow lights are available in a large choice of wattages; the most common are 250W, 400W, 600W and 10000W with the 600W being the most popular option. A HID grow light is made up of three parts:

1.The Ballast which contains the necessary electronics to ignite and run the lamp.
2.The Reflector that holds the lamp in position and reflects light down to the plants.
3.The Lamp which can be either a High Pressure Sodium (HPS) or Metal Halide (MH).

Ballasts

A ballast or power pack is at the heart of a HID lighting system. There are 2 types of ballast available – standard electromagnetic ballast and the more recent electronic or digital ballast. Both deliver a surge of electricity at a high voltage to ignite the HID lamp. After ignition, the ballast then regulates the electricity being delivered to the lamp for safe operation. Electronic ballasts are around 3-4% more efficient than electromagnetic ballasts, run quieter and can have dimming functions to control the lamp power.

Reflectors

HID reflectors come in all shapes and sizes, but are all designed to do one job reflect as much light as possible down onto your plants. The most efficient reflectors are about 95% efficient meaning of the original 100% light from the lamp, 95% is emitted by direct light from the lamp or reflected light from the reflector. Basically, even the best reflector will have around a 5% loss. A reflector should also help to create a uniform spread of light while avoiding hot spots of intense light. Some reflectors are sealed using a glass plate or tube and are air-cooled using an extractor fan to further reduce the heat emitted from the lamp and keep grow room temperatures down.

Lamps

Metal Halide MH

Metal Halide (MH) lights produce a lot of light in the blue spectrum. This colour of light encourages plant growth, particularly green, leafy growth and keeps your plants short and compact. MH lamps produce a broad spectrum of light (more so than HPS) and a small amount of UV which can help improve the quality of your produce. However, MH lamps are not as efficient as HPS, producing around 30-40% less micromoles.

High Pressure Sodium HPS

High Pressure Sodium (HPS) lamps emit mainly orange-red light. This band of light is best for fruiting and flowering plants but can also be used for vegetative plants with good results. HPS lamps are the most efficient grow light currently available and produce the best yields. Standard HPS lamps are slightly deficient in the blue spectrum; to supplement this you can use fluorescent lights or use a ratio of three HPS lamps to one MH lamp in the flowering period. Some HPS lamps are termed Dual Spectrum, which means that have an enhanced output in the blue spectrum. Dual spectrum lamps are touted as being an all-in-one veg and flower lamp, but their spectrum is still much more suited to flowering plants. Best results will be achieved using a MH lamp for vegetative growth and HPS lamp for flowering.

Top Tips:

  • If you want to supplement your HPS with extra CFLs, use the 6400K Cool White lamps as these will provide the blue light your HPS is missing.
  • Switching from a HPS to a MH lamp in the last 1-2 weeks of the plants life cycle can greatly improve the quality of your produce by enhancing essential oil production.

Relays and Contactors

When a ballast starts up, it draws a large amount of electricity for a split second so that it ignites the lamp. This spike of high voltage is enough to burn out a standard plug-in timer, so to successfully turn a HID light on-and-off automatically, you need to use a relay or a contactor. These devices use the timer as a signal, and draw the power through a 13-amp plug, rather than through the timer. One 13-amp relay can switch 1 x 1000W, 3 x 600W, or 4 x 400W HID lighting systems. Contactors are more heavy duty than relays and are used for larger indoor gardens with 4 or more 600W lights.

Other Types of Grow Lights

New technologies currently trying to improve horticultural lighting are light emitting diodes (LEDs) and light emitting plasma (LEP).

LEDs

Unfortunately, there has been a glut of cheap LEDs that have been launched in the hydroponics market over the years that have all over-promised and under-delivered. Many companies make claims that their LEDs are more efficient than HPS, but currently there are still no LED units that can produce yields that are close to comparable.

However, LEDs are a very promising area for supplementing light to change or steer the plants growth. The benefit of LEDs is they can be tuned to a specific wavelength to trigger a certain response or enhance a particular growth stage.

The common LED grow lights on the market that have a mixture of blue and red LEDs say they are tuned to match the two PAR peaks and drive targeted photosynthesis, but they are missing all of the other wavelengths (colours) that plants also need. Interestingly, the most promising LEDs to come to market during 2012 are the full spectrum LEDs that are designed to produce light across the whole PAR spectrum. However, the diode wattage and unit cost still means LEDs are not able to replace HPS lamps.

LEP

Light emitting plasma has come to market for the purpose of solar simulation. They produce a very broad spectrum of light, including UVs, which is close to natural sunlight.

LEP units can be used on their own for vegetative growth but are lacking in the red spectrum to produce a good yield of fruits or flowers. They are very good for supplementary light, particularly for adding in UV light to improve quality which is missing from most HPS lamp. The market leaders in LEP technology is Gavita Holland and we are sure there will be some great further developments in LEP lighting systems over the coming years.

HID Lighting – Helpful Tips

What lighting should I use in my grow room?

Your choice of grow light should be decided by the size of your growing area. Each type of HID grow light is suitable for a specified area. For guidelines on the type and number of lights you can put in your growing are see below.

Lamp Area Coverage:

  • 250 Watt = 0.25m2 – 0.5m2
  • 400 Watt = 0.5m2 – 1m2
  • 600 Watt = 1m2 – 1.5m2
  • 1000 Watt = 1.5m2 – 2m2

Hanging height – due to the heat that is emitted from HID lights, you should hang your lighting system according to size. The following is the recommended distance between the lamp and the plant canopy.

  • 250W = 30 – 40cm
  • 400W = 40 – 60cm
  • 600W = 50 – 70cm
  • 1000W = 75 – 100cm

Top Tips:

  • MH lamps emit more heat than HPS, so mounting heights will need to be adjusted depending on your lamp.
  • Use the back of your hand as a guide; if its too hot for your hand its too hot for your plants.

How Much Will it Cost?

To get the operating cost per hour for light, take the lights combined wattage, and divide it by 1000 to get the kilowatts used. Then multiply that number by the amount your electric company charges per kilowatt hour (you will find this at the top of your electricity bill). HID lights will use a little more than the stated wattage; a typical 600W system will use 640-660W. To find out the precise usage you can purchase a plug in power meter for less than 10, these will give you a digital reading of actual power consumption.

How do you provide a more uniform level of lighting?

If you find that your reflector is not throwing enough light out to the edges of your room, or is creating hot spots, you should look at investing in a better reflector to improve uniformity. If you are using a high wattage HID light such as a 1000W, you can use an overhead moveable track, known as a light mover, to move your light back and forth to create more uniform growth. These systems are worth investigating for high value hydroponic crops because a more uniform lighting pattern can help optimise yield.

CHOOSING THE RIGHT REFLECTOR

Light is one of the most important factors in your grow room, and with current energy prices they are becoming more costly to run. With this in mind do you think youre getting the most out of your light? One very important component to your grow light is the reflector. Every grow room is slightly different and in order to make it as productive as possible we stock a large range of reflectors to suit all growers needs.

Out of all the reflectors we stock at Aquaculture all are highly reflective with a dimpled aluminium finish. These can be organised into 3 categories:

  • Open
  • Closed
  • Air-Cooled

Open Reflectors

Excellent heat dispersal. These reflectors are used by the majority of growers; mainly because they are extremely versatile and are easy to use.

The Euro and Mantis reflectors fall into this category. Open refers to the two sided design allowing the reflector to be open at either end. This type of reflector allows the heat that the lamps create to easily escape, which means they can be positioned closer to plants than closed reflectors. The Mantis reflector (pictured above) is particularly good as it can be adjusted to allow for a wide or narrow spread of light to suit most grow room requirements. As well as allowing good heat dispersal; they inevitably let light escape from either end, making them suitable if you are using multiple lights in series. In single lamp applications this escaped light can be captured and used more effectively with closed reflectors.

Closed Reflectors

Optimised light distribution. This type of reflector has four or more sides to it which causes the light to be focused downwards, allowing for a more concentrated and uniform spread of light over a given area.

The Ultralite (pictured right), Superwing and Diamond are all considered closed reflectors. These reflectors are often used to optimise light output in single light grow rooms. They also come into their own when you want to maximise the efficiency of multiple lights to avoid cross over areas and lighting dead spots which can occur with open reflectors. With this design heat can build up within the reflector so higher mounting heights are necessary.

Air Cooled Reflectors

Reduces heat output. The Aerowing, Blockbuster and the Cool Shade (pictured right) are all classed as air cooled, their enclosed design allows air to be pushed past the lamp and ducted out of your grow room; massively reducing the grow room temperature.

As the light has to pass through heat resistant glass a small reduction in light intensity occurs (around 3-5%). However, much less heat is given off by air cooled lights, so the environmental temperatures are often more favourable.

You can hang these lights much closer to the plants which makes a very efficient grow room. Air cooled reflectors are excellent in summer months, or in small rooms where hanging height may be an issue. To use an air cooled light you need a minimum of 200 m3 of air to pass through the reflector every hour. This can be achieved by installing a separate ventilation system for your lights or by using your exhausted air from your grow room.

TIMERS AND CONTACTORS

Timers are used in growing to automate the process of turning on and off of your grow lights, whether you are in the Vegetative stage and have your lights on 18 hours and off for 6 hours, or you are in the Flowering stage and have your lights on for 12 hours and off for 12 hours.

If you are using a timer to control your HID lights, it is imperative that you use a contactor to protect your timer. Contactors insulate your timer from high currents thus ensuring that they cannot get damaged.

A common effect when if you don’t use a contactor when using a timer with a HID grow light is that the timer can become damaged and will not switch back off. This can leave your lights on continuously until you next check on them and this can cause havoc with the growth cycle of your plants. The only exception to using a contactor is if you are using a heavy duty hydroponics timer which specifically states that you do not need a contactor to operate it.

KEEPING YOUR GROW LIGHT SHINING BRIGHT

When growing indoors, the power and quality of your grow light is arguably the most important aspect of your grow room. Without a doubt, your grow light can really make or break your final yield. So how do you make sure that your grow light gives you the best possible results crop after crop? Read on for some top tips on keeping your grow light shining bright!

How bright is your bulb?

Simple fact; the light output from your grow light lamps will drop in intensity during the course of their working life. Whether you are using high pressure sodium lamps to produce flowers, or metal halide lamps to grow mother plants, it is a must that you replace your lamps on a regular basis.

So how often should you change your lamps? After 6 months? 12 months? Or every crop cycle? Ultimately, it comes down to how long they have been in use. However, not all growers use their lamps for the same time each crop cycle.

High Pressure Sodium (HPS) Lamps

HPS lamps efficiently produce mostly red/orange light, which make them suitable for flowering and fruiting plants. However, their efficiency in turning electricity into plant usable light also makes them suitable for vegetative growth.

When deciding to replace HPS lamps, we should always consider the amount of time they have been used, as opposed to the amount of crop cycles. Why? Well, quite simply, one grower may use their lamps very differently to another. Take the following example:

Grower A – This grower may choose to grow 4 big plants in a 2m x 2m x2m grow tent with four 400W HPS grow lights. He uses an 18-hour photoperiod when veging his plants for 6 weeks, and then flowers them under a 12-hour light cycle for 10 weeks. So every complete crop cycle he will use his lamps for 1,596 hours.

Grower B – Using a grow tent of the same size, this grower may choose to grow 12 smaller plants with the same 400W lights. He uses an 18-hour vegetative cycle for 2 weeks and then flowers for 8 weeks. So every crop cycle he will use his lamps for 925 hours.

For the Sylvania Grolux 600W Dual Spectrum Lamp, for the first 6,000 hours of use, the lumen maintenance (total light output) drops by 1% for every 1,000 hours of lamp-use. If all other growing factors remain steady between crop cycles (environment, nutrients, growing system, plant type, etc), the amount of light is directly proportional to crop yield. The example above shows that two different growers have very different crop cycles – each using their grow lights quite differently. So in order to know when your lamp needs replacing, you need to know how many hours it has been used for. After 12 months of back-to-back growing, Grower A will have completed 3 crops, whereas Grower B will have completed 5 crops. Both growers will have used their lamps for a similar amount of time, and both would have had a 3-4% light output reduction – which can equate to the 3-4% yield reduction.

So how often should you change your HPS lamps?

At Dr Greens we recommend using your lamps for a maximum of 4000-5000 hours approximately 9-12 months of continuous back-to-back growing. If you want to look at it more closely, the answer ultimately comes down to the value of your crop. If your lamp replacements are going to cost you 100 after 6 months of use, and a 2% yield reduction is going to cost you 200 it makes financial sense to replace your lamps.

Metal Halide (MH) Lamps

MH lamps are quite different to HPS. The blue light they produce makes them more suitable for vegetative growth or for supplementing multiple HPS lamps with extra blue light.

Over time, the light output of MH lamps decrease much faster than HPS lamps. Where a HPS will drop 2% after 2,000 hours of use, a MH lamp will drop 9%! As you can see from the graph (see below), the reduction at 4,000 hours is 15% for MH and 4% for HPS.

So how often should you change your MH lamps?

If you are using MH lighting specifically for vegetative growth and swapping for HPS lamps at the start of flower, you should change them every 2,000-3,000 hours of use (12-18 months of back-to-back growing, or 5-6 months of continuous 18-hour vegetative growth).

THE IMPORTANCE OF REPLACING REFLECTORS REGULARLY

Reflectors are very important for HID lighting systems that are powered by HPS or MH lamps. They help reflect light emitted from the top and sides of lamps, and a good reflector should reflect 50% more light than using a lamp without a reflector.

Reflectors are made from various types of hammered aluminium.The better ones are made from miro aluminium – which is around 96% reflective. Over time, and through heat exposure from the lamp, this reflective surface slowly oxidises; resulting in a significant drop in reflectivity. Data from the Dutch lighting manufacturer, GAVITA Holland, shows that even high quality miro aluminium will lose approximately 1% of reflectivity for every 1,000 hours the light is on this is in a clean greenhouse environment! Unfortunately for us, indoor growing environments are often much dirtier and dustier than greenhouses. Our reflectors are very close to our plants and will, over time, get dust, dirt and even stray foliar sprays deposited on the reflective surface. This problem is then increased tremendously for growers using humidifiers or sulphur vaporisers. If using a humidifier with tap water, you will see a white dusty deposit form on most grow room equipment (and even the plants leaves). This white dust is the bicarbonates from the tap water, and unfortunately makes reflectors not very reflective.

You can expect your reflector to lose around 5% of its original reflectivity over the course of 12 months in a clean grow room. This can increase to 10% in a grow room using humidification or a sulphur vaporiser. That 10% loss in reflectivity means 5% less light that your plants could be using.

So what can you do?

To maintain high reflectivity from your lighting system, it is essential to clean your reflectors regularly, and consider replacing them every 12-18 months for maximum light output. For advice on choosing the best reflector for your set up, feel free to visit us in store to speak to one of our friendly members of staff. Or alternatively, you can call 01952 200209 for any queries.to use a RO machine to filter the water when using a humidifier. This will generate pure water and remove the bicarbonates that decrease the reflectivity of your reflector.

  • When using a sulphur vaporiser, never have them burning when the lights are on.
  • Cleaning your reflector with a soft microfiber cloth and a mild acidic solution will remove some of the dust, dirt and bicarbonates from humidifiers. But remember, cleaning a reflector will never return it back to its original state, unfortunately.

The decrease in reflectivity is taken very seriously by commercial growers in the greenhouse sector that use artificial lights. Despite being on a budget, these greenhouse growers consider it very worthwhile to replace reflectors every 12 months! So to maintain high reflectivity from your lighting system, it is essential to clean your reflectors regularly, and consider replacing them every 12-18 months for maximum light output.

HOW TO TEST YOUR BALLAST OUTPUT

You can test ballast output for yourself! Follow this guide to see how your 600W magnetic ballast measures up.

Using an energy meter, available from online electrical stores for between 15 and 35, you can test the performance of a ballast by following these steps:

Before testing

Make sure you use the same type of lamp for each test.
Run in the lamp for at least 100 hours from new to stabilise the lamp ensuring consistent readings.
Repeat the tests more than once, preferably with different ballasts of the same type.

Testing Method

  1. Connect all equipment according to your manufacturer’s instructions.
  2. Ensure the power socket is switched off and plug the energy meter into it.
  3. Plug your ballast into the energy meter.
  4. Connect the reflector and lamp to the ballast.
  5. Turn the power on; allow the system to warm up for at least 30 minutes.
  6. Select the power setting (Watts) on the energy meter and then when the value is stable, make a note of it.
  7. Select the ‘Volts’ setting and make a note of the value. This can be any value from 216V to 255V, but usually it is somewhere around 240V in mainland UK.
  8. If your voltage reading was not 240V, you need to adjust it. As a rule of thumb, for each volt difference, adjust your power reading by the same value in percent.
    Here’s some examples:

    • If you recorded a voltage reading of 237V, this is 3V under 240V, so to compensate, you would apply 3% extra to your original power reading. If your original power reading was 630W, with an extra 3% applied this becomes 649W.
    • If your voltage was 242V, this is 2V over 240V so you would subtract 2% from your original power reading. If your original power reading was 630W, with 2% less this would be 617W.
  9. A properly performing 600W ballast will give a reading of approx. 655W.
  10. Preferably, repeat the above steps on more than one ballast of the same type and take an average of your results.

GROWING SYSTEMS

NFT

NFT (Nutrient Film Technique) is one of the most popular hydroponic growing styles mainly due to the compact, self-contained nature of the system. NFT systems are inexpensive, easy to set up and once you get growing, theres almost no growth media required. Furthermore, theres no need to dial in complex irrigation schedules as most NFT growers run the pumps 24/7 to create a steady film of nutrient solution for the plants roots to bathe in.

Whats so good about NFT?

At first glance, NFT might not seem that different to other hydroponic growing methods you may have explored. Nutrients are added to water just like any other hydroponic system and this solution sits in a tank. Plants sit on a grow tray above the tank and the nutrient solution is pumped up to the tray. Where the NFT differs from a Flood and Drain system is due to the tray that receives the nutrient solution being positioned so that it lies on a slight gradient. The nutrient solution is pumped up to the high end so that it flows along the length of the tray to the slightly lower end, creating a constant, flowing film of nutrient solution over the roots. Any nutrient solution that is not taken up by the roots simply flows back through a hole into the tank where it is re-circulated.

How can plants grow without Growing Media?

Your plants are constantly bathed in an oxygen-rich nutrient solution, this thin film is about 0.03 to 0.1 inches deep. Not only do roots enjoy the oxygen-rich nutrient solution but, because the film is so thin, they enjoy plenty of direct access to air too. This is a key feature of NFT thats worth really highlighting. There are always some parts of the root zone that have more access to oxygen than others, simply because they are higher up, but these parts of the root zone help to supply lower parts with all the oxygen they require. This is basic plant physiology in action and NFT growers exploit it to their advantage. When plants have access to all this water, nutrient and oxygen simultaneously the growth rates can be staggering.

Many NFT systems use a thin layer of capillary matting called a spreader mat which helps to spread the flow of the nutrient solution evenly over the entire surface of the grow tray. The root zone is protected from light with a piece of Correx (a cross between cardboard and plastic). Small holes are cut into the Correx, just big enough for the base of the plants which are normally in Rockwool cubes to fit through. This also helps to prevent algae growth in the root zone or nutrient solution.

Gro-Tanks vs. Gullies

NFT Gro-Tanks can accommodate a far wider root system than the NFT gullies you may have seen on commercial hydroponic farms (commonly used to grow basil and other leafy greens) making them ideal for plants that produce abundant root systems such as tomatoes.

Go with the Flow

NFT Gro-Tanks often come supplied as a complete kit for hobbyists-including the right sized pump. Solution flow is generally unimportant but should normally be between 320L and 1000L per hour. Channels should be sufficiently sloped, normally not less than 1:50 but may be much steeper if set-up allows, so that there is no pooling in the channels.

Plant Stability

Heavy, fruit-bearing plants like cucumbers and tomatoes may need some support, but not as much as you might think! The plants form such a thick mat of roots underneath the Correx that they do a pretty good job of supporting themselves. Of course, no matter what your growing style, some of the more top-heavy varieties will always benefit from some net supports-especially when you are driving them to their limits!

Propagation

NFT growers start their seedlings and cuttings off in the regular way, perhaps propagating in rockwool cubes or another inert media. Aeroponic cloning machines can also be used. Just as with any other hydroponics systems, its really important to make sure that your seedlings or cuttings have a sufficiently developed root zone before transplanting them into an NFT grow tank. Dont just wait for one or two roots to poke out, aim for a mass of roots first.

Planting out and Irrigation

First, mark your planting sites with a marker on the Correx sheet. Dont position any plant too close to the pump. Make the holes just big enough. The aim of the game is to allow your cuttings or seedling access to the nutrient film without letting light in through gaps. Lay a single layer of spreader mat over the grow tray. Run your pump 24/7, day and night. Theres no need to work out irrigation cycles and frequencies. Your plants will simply absorb as much or as little nutrient as they require. This is perhaps one of the most appealing aspects of NFT. You should be able to see obvious root activity within 24 hours of planting out. Root axes grow into the nutrient film. Fine root hairs will also grow around the propagation media.

One of the best aspects of NFT growing is the ability to peer at the huge mat of roots that quickly develops underneath the Correx cover. Its easy to assess the health of your plants-just look for a thick mat of white roots! Watch that the roots dont get carried away and grow into the pump. (Unlikely, but it does happen.)

Clean-up in between harvests is a lot less hassle than with media-based growing methods too, mainly because there is so little media to deal with. This makes NFT Gro-Tanks a great choice for the grower who doesnt want to endure the regular hassle and expense of carrying endless bags of soil, coco or clay pebbles.

GROWING IN SOIL

Growing in soil has always been a popular method with indoor growers, not only due to its ease of use and low maintenance, but because it also caters for those growers who like to grow organically. This is a brief guide on what soil is and how to achieve good results using it.

What is soil?

Technically, soil is a naturally occurring deposited and decomposing matter on the Earth surface i.e. earth/mud/garden soil. What we sell and call soil is actually known as soil-less growing medium or a compost, but as most growers still call it soil, so will we.

Most pre-mixed soils you will find in grow shops will contain mainly peat – which has good water and nutrient holding abilities; making it a good growing media for plants. Peat is a natural, partially decayed vegetative matter that forms naturally in wetlands or bogs. All of our soils at Aquaculture contain mainly peat that has been treated to ensure that it is clean and free from pests and disease. Some cheaper peat based composts from large garden centres will often not be treated and can be of poor quality.

Benefits of growing in soil include:

  • Can grow your plants organically
  • Easy to use
  • Inexpensive to set up
  • Bio-degradable

Growing In Pots

Because of the nature of soil, the most practical way to grow your plants is using pots and watering by hand.

Propagation of plants should be carried out in Jiffy pellets, Root !t Rooting Sponges , or a suitable seed soil and small pot. Once the seed or cutting has established and has plenty of roots you should pot them into small 10-15cm square pots using a soil that has a low nutrient content. Once the plants are well established in the pots (1-2 weeks later) and you can see plenty of roots at the bottom of the pot its time to pot up.

Note: You should always establish a small plant in a small pot, plants in over sized pots will take a long time to use all the water from the soil and often stay too wet for too long.

Choosing your final pot size is important, generally to take an average sized plant to full maturity you need a pot size between 10-15L. For growing very big plants, 30L should be the largest you consider. The pots size should generally reflect the size you want the plant to finish at.

For example, your room size is 1m x 1m x 2m (L x W x H). If you are growing 20 small plants you would choose a pot size around 4-7L, if you are growing 4 large plants you would choose a pot size around 10-15L, if you are growing 1 or 2 huge plants you should use 30L pots.

How to Water

The key to successful soil growing is to only water your plants if they need it. Below is a guide on how to water your plants:

1.You should water from the top until water runs out of the bottom and collects in a saucer.
2.The plants should stand in this water for 5-10 minutes, if the water has soaked back into the pot repeat step 1.
3.Lift the plant out of the saucer and allow water to drain from the pot.
4.Empty and discard the water in the saucer.
5.The plant and soil is now fully watered, note how heavy the pot feels.

Repeat steps one to four when the pot feels about half the weight of a fully watered pot, this can take up to 3 days in early vegetative growth and as little as 1 day for fully grown flowering plants. It is important to not allow the soil to dry and shrink in from the sides of the pot.

The process above gets the whole root zone working throughout the entire pot. It is important to allow the soil to dry slightly between watering as keeping it too wet will damage the plants roots and overall health.

Using Liquid Nutrients

Your soil will need fertilising at some point during its cycle. If you are using a light soil with little nutritional content, you will need to start using nutrients after 7-10 days. If you are using a rich soil like you will need to add nutrients after 21-28 days. Generally, your plants will tell you when they need nutrients when the lower leaves on the plant start to turn a lime-green colour. Some plants need more nutrients than others and so looking at your plants and getting a feel for them is very important in soil growing.

Mineral or Hydroponic Nutrients

These should be used for soils at a low strength (CF10-14/EC1-1.4) to avoid over-fertilisation. These nutrients are generally cheaper to use with soil but easy to over fertilise. When using mineral nutrients every day, it is a good idea to use water only week to avoid nutrient build up.

Organic Soil Nutrients

At Dr Greens we recommend using organic nutrients. Organic nutrients tend to promote a better flavour and are more forgiving than mineral based nutrients. Organic nutrients also cause the micro-life (bacteria, enzymes, fungi etc) in the soil to proliferate which in turn helps to protect the roots and feed your plants. When watering frequently with organic nutrients it is a good idea to use water once a week to avoid over-fertilisation. When using organic nutrients you must be sure to use them within 24 hours of mixing as they do not keep well once diluted into water.

Soil and pH

For nutrients to be absorbed by the plants roots and for the soil to stay healthy the optimum pH is between 6.5-6.8. Soil is forgiving and has a good buffering capability but if you constantly water your soil with tap water higher than a pH of 7.5 you will slowly alter the soil pH and make some nutrients unavailable. If you do need to lower the pH of your water make sure you dont go any lower than 6.5 as it will damage the essential bacteria, fungi and enzymes in the soil. It is much easier for the soil to buffer the pH down rather than up.

To alter the pH of your tap water use pH down (phosphoric or nitric acid) or if you want to stay organic use Cannas organic pH down (citric acid). Adding nutrients to the water will lower the pH so if you are using nutrients always check and adjust the pH after adding them.

Troubleshooting / FAQs

Q > My Plants are wilting. A >Under watered or Over watered.
Q > The plants lower leaves are turning lime green. A >Under feeding.
Q > My leaves are dark green, curling down and have burnt tips. A > Over feeding.
Q > There are lots of little black flies buzzing around soil. A >These are fungus gnats a.k.a. Sciarid flies, can be a sign of keeping the soil too wet. The larvae eat the roots and can cause serious damage. Treat with beneficial Nematodes, Gnat Off and sticky traps.
Q > I have lots of small jumping insects in the run-off and on top of the soil. A > An insect called ‘springtails’, which are totally harmless.

GROWING ORGANICALLY

What does organic mean?

Other than the traditional scientific definition of containing carbon, organic growing is a term now used to describe a more natural, holistic approach to growing plants. This encompasses avoiding the use of chemical pesticides, fungicides and artificial fertiliser/ liquid nutrients.

Typically, in an organic garden, the grower will be using an organic growing media that is free from chemicals and is biodegradable along with dry or liquid nutrients and additives that contain plant or animal extracts, not refined mineral salts (chemicals).

How does organics work?

When you grow a plant using organic growing media and nutrients, there are some differences in the way the plant has access to nutrition in comparison to hydroponics.

In hydroponics, the plants are given nutrients that are already in an available form. This means the nutrients are taken up into the roots straight away.

When you water your soil with an organic nutrient, most of the elements that end up in and around the root zone cannot be taken up straight away by the plant. The elements need to be converted into a form that the plant can use – this is done by small microbes in the soil (bacteria, enzymes, fungi and protozoa) and the process is known as mineralisation. This means that the health of your soil becomes very important as it is a living system that nourishes the plant.

Organics Pros and Cons:

Deciding to grow organically is often a conscious choice to try and grow plants in the most natural way possible. But in reality, there are not many extra benefits when compared to hydroponic growing. Organic growing is slower than hydro – especially in vegetative growth – but it is a lot easier to maintain than a hydroponic system.

Controlling the nutrition in the root zone is more difficult because of the lag time between using the nutrients and them being available to the plant. This uncertainty with feeding is often counteracted by using nutrients every other watering or using water only once a week. If you ask an avid organic gardener, they will tell you that you develop a feel for what the plants need. It is this predictive interaction with the plants that a lot of organic growers learn to love and take pleasure in.

Organic Certification

There are many brands of nutrients and soils that will claim to be organic. To be certain that you are using quality products, make sure that they have certification from a recognised organisation. There are many organisations world wide that will approve a product as organic, but you must be aware that these organisations have different standards. Look for one of the following widely accepted organisations to be sure of its quality:

  • Soil Association – the UKs leading certification organisation
  • OMRI Organic Materials Review Institute, principal organisation in the USA
  • CU – The Control Union Certifications organisation, maintains worldwide supervision of input products that are used in organic farming.

Recommendations

At Dr Greens, we firmly believe that BIOBIZZ are the market leaders in supplying top quality products to produce organic crops. Certified by OMRI, their products are of premium quality and produce excellent results. We have many happy organic growers that have been using BIOBIZZ nutrients since we started selling them.

How Do I Grow Organically?

For more detailed instructions on how to grow using soil and liquid nutrients please refer to our Growing in Soil article.

What equipment do I need?

Pots and saucers, certified compost/soil, certified liquid nutrients, and lighting and ventilation as with any indoor garden.

5 Top Tips:

1. Check your soils nutrient content before starting.
2. Use a weak soil for propagation and a richer soil for potting on.
3. Do not use nutrients until your plants need them
4. Feed every other watering.
5. Use your organic nutrients within 24 hours of mixing.

AEROPONICS

Once oxygen was realised to be the most important root stimulant, it became obvious that none of the existing hydroponic systems had maximized the air available to roots. Aeroponic technology has managed to achieve optimal oxygen supply to the roots by spraying or misting roots in an air filled chamber with a nutrient rich solution.

So why use aeroponics?

  • Rapid root growth due to optimal oxygen supply.
  • High dissolved oxygen content of the nutrient solution reduces risk of disease.
  • No need for disposal of any growing media.
  • Able to monitor the growth of the roots as there is no media to block your view.
  • Flushing or changing nutrient strength is effective instantly as solution is directly applied to the roots with no media to act as a buffer.
  • Temperature around the root zone can be controlled using a water heater.
  • Can be used from propagating cuttings or seedlings to growing plants to full maturity, without stressing the plant during transplanting.
  • Systems are tidy and compact to fit in small grow spaces.
  • No need for timed irrigations as there is a constant supply of solution and oxygen.

Aeroponic Systems

At Dr Greens we stock quality brands that use aeroponic technology in their systems. Growers have specific needs and we supply systems which cater for your specific needs.

Aeroponic Propagators

During the propagation period your plant is at its most vulnerable stage, and it is common for some people to not get good results. If it is vital for you to achieve a high success rate of rooting cuttings – for reasons such as limited space or an inability to take many cuttings from a mother plant – then aeroponic propagators are a good option. Many people judge the moisture content of the growing media (in other systems) as either too much or too little; this will either starve the roots of oxygen or dry the roots out.

Aeroponic propagators will supply the roots with an optimum ratio of nutrient solution to air – perfect for people who have trouble judging the moisture content of media. They constantly sprinkle the roots with nutrient solution so if people find their media dries too quickly and do not have time to keep watering cuttings, then it is ideal as the moisture content at the roots is constant. Because of total control of nutrient delivery, plants will be encouraged to root faster and be ready for transplant earlier.

X-Stream Aeroponic Propagators

The X-Stream range from Nutriculture offer a range of quality aeroponic propagators at an affordable price.

With each X-Stream Aeroponic Propagator, you get a propagator base (tank) and lid, heavy duty correx plate, 1.5 net pots, pump, delivery system and detailed instructions. Their design comes in a range of sizes to suit most growers needs.

Dr Greens Tip:

If using a water heater to optimise the temperature around the root zone in the 12, 20 and 36 plant systems, do not use a heater that is over 50 Watts. A heater that is too powerful will cause the temperature of the water to exceed the optimum temperature before the thermostat takes effect.

Amazon

Previously, aeroponics has been unfeasibly expensive for most home growers. That is why Nutriculture, a company who has consistently provided the market with unique and reliable products, had taken two years to develop a top quality system that gives high end aeroponic results at an affordable price.

Amazon Single

The system is based on the same principles as their aeroponic propagators, but can grow plants to full maturity.

  • The 50L tank gives the grower ample time before the solution is used up by mature plants.
  • The large root chamber provides space to grow a colossal root mass.
  • The powerful sprinkler system provides an even spread of solution to the roots with no blind spots.
  • A great variety of lids are available offering sites for 4, 8 or 16 plants in either 1.5 net pots or 3.

Twin Amazon

The Twin Amazon has been long awaited by growers who wanted to grow more plants using the system but without the hassle of filling up more than one nutrient reservoir. The Twin Amazon uses two root chambers linked to one nutrient reservoir; this will save the grower time spent on making the nutrient solution for two separate systems.

System features include:

  • 100L tank, ideal for running the two root chambers.
  • Two large root chambers, these are the same as the single amazon chambers.
  • A powerful sprinkler system providing ample nutrient solution to the roots.
  • A great variety of lids are available offering sites for 8, 16 or 32 plants in either 1.5 net pots or 3.

It is convenient that both the X-Stream Aeroponic Propagator and the Amazon system are able to use the same size net pot in which seeds or cuttings can be grown. Rooted plants brought up in the propagator are easily transferable to the system, minimizing the effects of transplant stress that is commonplace in other systems. However, it is optional to get lids with 3 holes to grow plants with thicker stems and greater root mass. It is simple to transplant seedlings or rooted cuttings in 1.5 containers into 3 net pots by filling the gaps with small 4-8mm clay pebbles.

GROWING IN POTS

Growing in pots has been popular with growers of all abilities for many years. Its certainly one of the least expensive ways to grow, making it perfect if youre on a budget. However, using pots does require a degree of technique, so below we give you some tips…

What are the benefits of growing in pots?

  • Easy to set up and maintain.
  • Very cheap.
  • Great if you want to grow a few or lots of plants.
  • Choose between soil, coco coir, hydroponics or even organics.
  • Suits all grow rooms.
  • Suitable for growers of all abilities.

What size pots do I need?

No matter what type of growing media you choose to use, you need to use the right sized pot for the size of your plant. A newly rooted seedling or cutting will need a small pot approximately 300-500ml in volume. Once well established with a healthy root system, transplant the seed/cutting into a medium sized pot with a volume of 1.5-3L. Once it has entered the vigorous growing phase and has a healthy root structure, it can be transferred into its final pot.

Dr Greens Tip:

You should always establish a small plant in a small pot; plants in over-sized pots will take a long time to use all the water from the growing media and often stay too wet for too long.

Choosing your final pot size is important, generally to take an average sized plant to full maturity you need a pot size between 10-15L. For growing very big plants, 30L should be the largest you consider. The size of the pot should generally reflect the size you want the plant to finish at.

How often should I water the pots?

The key to successful grow using pots is to only water your plants if they need it. Below is a guide on how to water your plants:

1.You should water from the top until water runs out of the bottom and collects in a saucer.
2.The plants should stand in this water for 5-10 minutes, if the water has soaked back into the pot repeat step 1.
3.Lift the plant out of the saucer and allow water to drain from the pot.
4.Empty and discard the water in the saucer. This waste should be between 10-25% of the input volume (e.g. if you pour 2L through the top, 200-500ml should come out the bottom)
5.The plant and growing media is now fully watered; note how heavy the pot feels.

Repeat steps one to four when the pot feels about half the weight of a fully watered pot, this can take up to three days in early vegetative growth and as little as one day for fully grown flowering plants. It is important to not allow growing media like potting soil or coco coir to dry and shrink in from the sides of the pot. If this has happened you have left it too long between watering.

How much nutrient should I use?

If you choose to use a hydroponic growing media like coco coir or rockwool, you will need to use nutrients from day one and every time you water. Start with a low dose and increase the nutrient strength as the plants develop.

When using potting soil you need to check the initial nutrient content. If you choose to use a potting soil with a high nutrient, you do not need to add nutrient for the first two to four weeks after potting. However, if you are using a potting soil with a low nutrient content, you will need to use nutrient after the first one to two weeks. Once you start using liquid nutrients, only use every watering or every other watering.

When using hydroponic growing media, such as rockwool or coco coir, you should check the nutrient strength of the input solution and the collected run-off using a conductivity meter. If you are feeding correctly, you should find that the run-off solution will be slightly higher than the input solution.

Hint – due to conductivity readings from run-off not being very accurate, the use of a Fertometer can be very helpful. It is a simple tool that tells you how strong the nutrient is in a pot.

AUTOPOTS EXPLAINED

AutoPot systems have been a firm favourite with many growers, particularly beginners that are new to hydroponics. This is mainly due to the simplicity and flexibility the AutoPot system offers, combined with the excellent results they can deliver.

The Aquavalve (pictured below) is the irrigation controller for all AutoPot systems. The Aquavalve is essentially an intelligent float valve that delivers fresh nutrient solution to the tray when the plant needs it without the need for electricity. A normal float valve would maintain a constant level of water in the tray which would inevitably lead to poor plant health and growth as the growing media would become waterlogged.

Aquavalves

The Aquavalve fills the growing tray with nutrient solution to a pre-set depth of 20mm, and once this is reached, the valve stops filling. When nearly all of the solution has been used by the plant and the tray has little nutrient solution, the Aquavalve refills the tray with fresh solution. This method of filling the tray and allowing it to run down before being refilled is the fundamental principle behind the AutoPots success. AutoPot have termed this watering technology Plant Controlled Irrigation.

Which Growing media?

In order for the plant to make best use of the nutrient solution being delivered to the tray you must use a suitable growing media in the pot. The growing media must have good capillary action, this means it must be able to suck up the nutrient solution from the bottom of the tray and spread it throughout the pot.

Through our own trials in the Aquaculture greenhouse and through customer feedback, we have found the best growing media for the AutoPot is Coco Coir. Coir has a great capillary action and holds water well, while at the same time being a good store of nutrients and oxygen. Unlike potting soil or peat based composts, coir will not excessively hold onto nutrients; making them easily available to the plant and help avoid over fertilisation. The addition of perlite helps keep the coir at a good air-to-water ratio, which is essential for healthy root growth and nutrient uptake. We recommend mixing 25% perlite to coir for optimum results.

VitaLink Coir Mix is a good alternate to mixing perlite in coco coir, and works very well with AutoPots. This contains a mix of 70% fine coir and 30% coarse coir chips, which provides good water holding, has a good capillary action which is essential for AutoPots and has a good air to water ratio.

It is also possible to use other hydroponic growing media such Grodan Grow Cubes, Mapito or Perlite, as all of these substrates have a good capillary action and nutrient holding properties. If you are an avid soil/compost grower, you can use AutoPots as long as you mix your potting mix with 25-30% perlite and use a low strength mineral based nutrient (organic nutrients will not keep well in the tank and can block up pipe work).

System design

One of the many benefits the AutoPot systems offers is its suitability to all growing areas. AutoPot offer two different systems, The Easy2Grow and the One Pot System.

AutoPot Systems

Easy2Grow System

With this system 2 x 8.5L pots sit inside one large tray with one Aquavalve feeding both plants. These systems are great for growing 2 smaller plants or plant types that grow tall not bushy. These 2 pot systems can be connected in series and run off one reservoir. It is important that with these 2 pot systems you use the same plant type, both being the same size on planting. If you pot 2 different plants with different growth habits, you can get a dominant plant and a weak plant. This happens because when one plant uses more nutrient solution that the other, it dominates the Aquavalve. This means that one plant undergoes the wet-dry cycles whereas the smaller (or less dominant) plant will have constantly wet growing media. For this reason you must ensure that you use 2 plants of the same size with the same growth habit.

One Pot System

These are generally the most popular system as they have one Aquavalve controlling each 15L pot. These pots can be moved around and are more capable of growing larger plants. These systems are commonly linked to one large reservoir.

Both of the systems can be customised to meet your requirements by selecting the required amount of modules to be run off a single reservoir. Technically, there is no limit to the amount of modules you can run off a single reservoir, but the following is recommended:

  • 1 – 4 modules would need a 47L reservoir using 4mm tubing
  • 4 – 10 modules would suit the 100L reservoir using 13mm tubing
  • 10 – 20 modules requires a 220L reservoir using 13mm tubing
  • 20 – 30 + modules would require a 350L reservoir using 13mm tubing

When setting up any AutoPot system using a 47L reservoir, the use of an inline tap just after the reservoir is highly recommended. This will enable you to have the option to turn off the water supply to the valves.

When using the larger reservoirs we recommend using 13mm tubing. This allows easy movement of nutrient solution through the tubing which prevent blockages. When using 13mm tubing we recommend you terminate the supply tube with a 13mm tap. This will allow you to flush the pipe work periodically to clean out any residues. To connect the Aquavalve to the 13mm supply tube, 13mm > 4mm X connectors are used.

Set up preparation

To prepare the AutoPot system for use, you must make sure the Aquavalve is set correctly.

*Please Note: The Aquavalve is not ready to be used when it is new and will also need re-setting after you have completed a crop. Detailed instructions on setting the Aquavalve are included in the booklet that comes with the kit pack or alternatively are available on the AutoPot Website.

All you have to do is remove the yellow silicon plug from the top float, roll firmly between you thumb and index finger, and replace it firmly making sure that the silicon covers the hole. After doing this you will find that, when you place the Aquavalve on a flat surface, the base of the top float will be raised off the surface sitting in a horizontal position.

This picture shows a correctly set Aquavalve on the right compared to one that needs setting on the left. Remember; if you do not set the Aquavalve correctly it will not work properly!

Aquavalves

Potting Up

When your plants are ready to be potted into their final AutoPot square pots, there are a few things you must do before planting. The first and most important thing is to make sure you use the root disks. Your should use two for each pot – one is thin and black on both sides and is called a Marix Disk, whilst the other is thicker with copper on one side and black on the other and is called the Root Control Disk.

The Marix disk should be placed inside the pot, this helps prevent growing media getting into the tray and interfering with the Aquavalve. The root control disk is placed in the tray gold side up; this prevents roots growing out of the tray and into the Aquavalve.

To prevent the bottom layer of growing media in the pot staying too wet, a small layer of clay pebbles can be used. This layer should be a maximum of 2cm (1inch) thick to avoid interfering with the capillary action of the growing media. Using clay pebbles is not essential but helps prevent the bottom of the pot becoming overly wet.

For optimum aeration throughout the growing media an air cage/dome can be used. See below on advice with using air cages/dome.

Once you have the pot ready, it is time to pre-soak the growing media. Compost/soil do not need pre treatment before planting, whereas coco coir, perlite and rockwool do. It is advised that you use a nutrient strength of 0.2 EC units (2 CF units) higher than you were previously using during the last stages of propagation. Most growing media can be prepared by placing it into the pot and watering it through with a nutrient solution. Allow the runoff to completely drain out and discard. Grodan grow cubes should be fully saturated in nutrient solution with a low pH (5.5) for 12-24 hours.

Once the growing media is ready for planting, transplant your healthy cutting or seedling into the pot. If your plants are in 3 or 4 rockwool blocks, make sure they have plenty of roots showing before planting. It is also important you do not completely bury the block in the growing media, instead you should only bury half of the block in the media at the top of the pot. This will prevent the block from becoming overly wet.

To finish off, we recommend using a top layer of clay pebbles or coir chips. This will prevent the top layer of growing media from becoming too dry due to evaporation. This top layer, or mulch, is more important when using growing media that has a high air content like Grodan Grow Cubes.

Establishing

After you have planted your plants into their pots, pour a small amount of nutrient solution through until you get some run-off. This runoff should then be discarded. It is important at this point that you do not start feeding your plant with the Aquavalve. The AutoPot irrigation system is suited to established plants with healthy root systems. Therefore, you need to wait until your plants have established roots throughout the pot before utilising the Aquavalve. This should take approximately 14-21 days and during this period you should hand water your plants from the top of the pots using the following technique:

  • Water from the top until water runs out of the bottom and collects in the tray.
  • The plants should stand in this water for 5-10 minutes, if the water has soaked back into the pot repeat step 1.
  • Lift the pot out of the tray and allow run-off to drain from the pot.
  • Empty and discard the run-off in the tray.
  • The plant and growing media is now fully watered. Note how heavy the pot feels.

Repeat steps one to four when the pot feels lighter – approximately half its original wet weight. This can take between 2-3 days, depending on what type of growing media is being used. It is important to not allow the growing media to dry too much and shrink in from the sides of the pot.

Environmental conditions are important when establishing the plant. Try to keep the humidity between 60 – 70% and temperatures between 24-26C. If you cannot keep the humidity up in your growing area you should consider using square humidity domes on top of the pots.

All Systems Go

Once the plants have established well into their pots and you can see vigorous vegetative growth occurring, it is time to start using the Aquavalves. On your first tank, fill use the same nutrient strength you have previously been hand watering your plants with. On subsequent tank fills you should take the following into consideration:

  • With the AutoPot systems all the solution is sucked up into the pot.
  • If your growing environment is hot (above 28C) and dry (below 50% RH), the plant will take up the water and not use as much nutrient. Over time this nutrient can accumulate in the pot and start to cause over-fertilisation. To avoid this you must use lower than normal nutrient strengths with an upper limit EC of 1.4 – 1.6 (CF 14 – 16) when temperatures are high and/or humidity is low.
  • If you have favourable environmental conditions with an optimum temperature (24-26C) and a good relative humidity (60-70%), your plants will perform well in their AutoPot systems because the nutrients and water can be taken up at a more equal rate.

Dr Greens Tip

Be sure to avoid using nutrients and additives in your reservoir that may cause blockages in the pipe work and in the Aquavalve. If you wish to use an additive that you think may cause blockages you can simply turn off the nutrient solution supply, allow the plant to use up the remaining solution in the tray and water your desired mix through the top of the pot.

If you are using compost/soil in your AutoPot we recommend you use a mineral based nutrient like VitaLink Earth or Canna Terra. The nutrient strength in the reservoir should be maintained at 1/2 strength. This will be approximately 0.6-0.8 EC (CF 6-8), not taking any background readings from the source (tap) water. This is recommended because compost/soil has a tendency to hold onto nutrients much more so than hydroponic growing media like coco coir and rockwool. Using nutrients at half strength will counteract nutrients building up in the compost/soil.

Many growers using AutoPots use a 1-in-3 reservoir technique to maintain a healthy EC in the pot. This entails using normal nutrient strengths for 2 tank fills, and only half (or a third) of the usual dose for the third filling of tank. Using a weak solution in 1 in 3 tank fills errs on the side of caution and works well when the grow room environment varies between too hot and moderate during the summer months.

Maintenance

An important factor to manage with the AutoPot system is the nutrient strength. Keeping a close eye on the EC in the reservoir and the pot will lead to a healthy and successful crop.

An easy way to check the nutrient strength in the pot is to shut off the supply of nutrient solution and allow the tray to become empty. Once the tray is dry, take a jug of nutrient solution from your reservoir, note the pH and EC, and slowly pour through the top of the pot until the tray is full with run-off solution. Take a sample of the run-off from the tray with a syringe and measure the pH and EC. You should expect the EC to be slightly higher (EC 0.2-0.4 CF units) and the pH to be between 5.5 and 6.5.

If the nutrient strength is too high for your plant, you have a few options. You can refill the reservoir with a weak nutrient solution (EC 0.5-1.0/CF 5-10) and continue using the Aquavalves. Or, or if your plants are showing signs of over fertilisation (burnt and curled leaf tips), keep the Aquavalves turned off and top feed your plants for a few days with the weak nutrient solution. Avoid flushing using water only as large swings in nutrient strength around the root zone can cause further stress to your plant. Your aim is to slowly reduce the nutrient strength back to your desired acceptable level, not flush out all the nutrients.

If after testing the nutrient strength you find that it is lower in the pot than in your reservoir, then you should increase the nutrient strength. Remember, only increase your EC by 0.2 units (CF 2) every 1-2 days as a large change in nutrient strength may negatively affect your plants.

If you use a filter with your AutoPot system, it is very important that you check and clean the filter regularly. If it is a sponge filter that is positioned inside your tank, then it is advisable that you clean the sponge every time you refill the reservoir. If you use an inline filter it should be cleaned every 2 weeks. A poorly maintained filter can result in disrupted nutrient solution supply and even block the Aquavalves.

Generally, if you keep clean and make sure your reservoir and AutoPot trays do not get contaminated with debris, your Aquavalve should work perfectly for the duration of your crop. If you are growing long term crops you should service your Aquavalves every 3 months.

Dr Greens Tip:

Your Aquavalves should be serviced after every crop. Servicing instructions are found in the AutoPot booklet that comes with the kit pack.

A quick service involves turning off the supply to your valves and letting the plants use up the solution in the tray. Once the trays are dry and the valves have completed their wet/dry cycle, remove the valves, check if the top float needs setting and, using a paperclip, check if the solution supply hole under the bottom is free of debris by poking the outstretched paperclip through the hole.

Using Air Cages

An air cage or air dome is a device that increases the amount of air around the root zone. An Air cage is placed at the bottom of the pot and actively bubbles air through the nutrient solution in the bottom of the pot and through the growing media above. This greatly helps with fast vegetative establishment, improves root health and as a result, increases yields.

An air cage is not essential for your AutoPot system to work well, and you can get excellent results without them, but trials in our own greenhouse have proven they greatly improve your results.

All you need to do is place your air cage at the bottom of the pot, use a small layer of clay pebbles around the air cage (around 2cm thick), cover with your choice of growing media and plug it into an air pump. It is recommended that each air cage receives an output from an air pump of between 100 and 200L per hour.

FLOOD AND DRAIN

There are many hydroponic systems on the market for you to choose from. During our time in the industry, we have seen the flood and drain system become increasingly popular. It is renowned for its ability to allow you to achieve fast growth and good yield with minimum fuss. Here, we give you details on how a Flood and Drain system works and how you can get best results.

What is a Flood and Drain System?

A Flood and Drain System (also known as Ebb and Flow) is an Active system that uses growing media. An Active system delivers nutrient to your plants roots via a pump at regular intervals. This pump can be controlled automatically by the use of a timer for convenience and accuracy.

What are the main advantages of a Flood and Drain System?

  • Relatively easy to use; making it suitable for beginners and advanced growers.
  • Low maintenance – possible to achieve good yield with little fuss.
  • Provides the root zone with lots of oxygen for fast growth.

Flood and Drain Systems are very simple in the way they work:

  • You grow your plants in containers/pots.
  • When your plants need irrigating, a pump is activated by a timer that fills the container from the bottom with nutrient solution. This is known as the flood cycle.
  • The container fills from the bottom up until the desired flood height is reached, which is normally just below the surface of the growing media.
  • Once the flood height has been met, the pump filling the container stops and initiates the drain cycle.
  • The nutrient solution is drained from the bottom of the container, usually from the same place as it fills from.
  • As the solution drains away, excess nutrient is washed out of the growing media and oxygen is drawn into the root zone. This provides an excellent root environment, promoting fast growth rates.

Which growing media is best for a Flood and Drain system?

You should always use a freely draining growing media with a good air-to-water ratio. At Aquaculture, we recommend clay pebbles. These are expanded balls of clay 8-16mm in diameter. They have a porous core with a hard outer shell. As well as providing ample air space (lots of oxygen for the roots) and sufficient water and nutrients, the roots are well supported, providing everything your plants need for fast and healthy growth.

Some growers blend clay pebbles with coco coir, at ratios of 50% clay to 50% coco or 75% clay to 25% coco. Such blends enable the growing media to hold onto water for longer, which decreases the amount of floods needed. This technique is more suited to growers who struggle to get their flood frequencies right, and can also help to stabilise pH drift.

NB – The most important factor to consider when choosing your growing media is that it dries slightly between flood cycles. If the growing media stays too wet, your plants root zone will be starved of oxygen. This will cause poor growth and limited nutrient uptake, but worst of all, the roots will be prone to root disease.

Flooding Requirements

To achieve the best results from a Flood and Drain system, you must get your flood frequency, height and duration correct.

Flood Frequency

As a general rule, if youre using clay pebbles and cultivating fast-growing plants with a high water and nutrient demand (e.g. tomatoes, peppers, roses), you should be flooding once every one to four hours. If you are using a coco and clay pebble mix, 1-2 floods a day will suffice.

Flood Height

If you use 3 or 4 inch rockwool cubes to propagate your plants and are planting into clay pebbles, the flood height should reach the bottom third of the cube. If you flood too high, you could over saturate the rockwool cube. However, if you flood too low, you could let the cube dry out. When using coco/clay pebble blends, you can have a slightly lower flood height because the nutrient solution can be drawn up higher in the container by capillary action.

Flood Duration

If you are using clay pebbles, once the desired flood height has been reached, you should hold it there for approximately one minute before switching off the feed pump and starting the drain cycle. This helps to purge any old nutrient from the surface of the clay pebbles. When using coco/clay pebbles blends, you should start the drain cycle as soon as the desired flood high is reached. This avoids the coco becoming too wet.

OPTIMISING THE IWS FLOOD AND DRAIN SYSTEM

Modular Flood and Drain systems like the IWS have become the most popular pot based hydroponic systems available. With many growers now using these flood and drain systems we thought it would be helpful to give some detailed information on fine tuning IWS systems to get the best results possible.

We have reaped the benefits of the IWS flood and drain systems in the Aquaculture greenhouse for many years and through our experience we hope to pass on some valuable advice that can help you achieve excellent results.

This article is not an introduction to flood and drain, if you want some basic information about what flood and drain systems are, and how they work, then please read our Flood and Drain article. Also, this article will not tell you how to assemble your IWS system, for this information refer to the IWS Flood and Drain Instructions booklet that comes with the system, alternatively this is also available to download from our website.

Please note that this information can be applied to other pot based modular flood and drain systems such as the Multiflow.

Basic Principle

Flood and drain is an irrigation technique that fills the pot with nutrient solution from the bottom. As the nutrient solution rises in the pot it forces out the air and saturates the growing media. Then, when the nutrient solution drains from the pot, fresh air is pulled down into the growing media enriching it with oxygen vital for healthy root growth. Frequent flooding and draining of the pot should occur in order to optimise the available oxygen in the root zone.

Which Growing Media?

This common question has no correct answer, simply because the growing media you choose to use often comes down to personal preference. Good results can be achieved with many different medias and mixes, but the key features you should look for in your media are:

  • Low-medium water holding capacity (WHC).
  • High air filled porosity (AFP).

A growing media that is ideal for flood and drain without the need for anything to be added or mixed in, is clay pebbles. This is Aquacultures recommend growing media for flood and drain, as there is plenty of air space between the pebbles to create a high AFP. They also are capable of absorbing and releasing nutrient solution from their porous structure. Clay pebbles can be flooded frequently with a low risk of over watering, which helps keep the root zone replenished with lots of oxygen and fresh nutrients.

Did you know A 10L pot of dry clay pebbles can absorb up to 5L of water! This shows just how porous they actually are.

It is also possible to mix coir (coco) with clay pebbles to increase the WHC. When mixing coir into clay pebbles, it should make up 20-40% of the total volume of the growing media. Adding coir will allow more time between floods, which means fewer floods each day.

Hint – If you fancy mixing coir with clay pebbles Aquaculture recommends mixing 25% coir to 75% clay. Mixes containing up to 50% coir can stay saturated for long periods which undermines the basic principle of Flood and Drain.

Understanding the Flood cycle

To get the best possible results from your IWS Flood and Drain system you must ensure you get the flood cycle right. The flood cycle is made up of 3 elements:

  • Flood Frequency -This is how often you flood the pot, which largely depends on what type of growing media you are using and how well established your plants are.
  • Flood Height – This is how high the water goes up the pot. Generally we recommend you always flood to the maximum height.
  • Flood Duration This is the total time of each flood and will depend on the size of your system and your choice of growing media.

These all play an important role together in getting the irrigation strategy as accurate as possible.

Setting Flood Height and Duration

This guide can be followed for all growing media, not just clay pebbles, and should provide accurate flood times and optimum results.

When you have put the system together, it is time to get the growing media prepared. Wash the clay pebbles thoroughly to remove the dust and small particles – this can be done with tap water. Insert the root control disk copper side up and add the clay pebbles to the bottom of the pot, before adding your chosen growing media on top. Only fill the pots three quarters full with your growing media at this point.

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Please note: No matter what growing media you use in your pots, you must use 5-10cm (2-4 inches) of clay pebbles in the bottom of the inner pots. This will help prevent the bottom withholding too much water.

Now fill the reservoir with water and add nutrients to a suitable strength – this should be slightly higher (2 CF units, 0.2 EC) than your plants have been getting during propagation. Use a root stimulator for quick establishment, and finally adjust the pH to 5.5-6.5.

Now the nutrient solution is ready, turn on the timer and start a flood cycle. Make sure the switch is set to minutes and the dial is turned all the way to the right for the longest possible flood time. The brain pot will start to fill and so will the pots. As the solution slowly fills the pots the growing media will take in the pH balanced nutrient solution preparing the growing media for planting.

Your aim here is for the maximum flood height to be the same as the amount of growing media in the pot.

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You should be able to see the water level rising to the surface of the growing media. Check by lightly pushing down on the media surface with the palm of your hand, this will make sure the media isnt floating up. If the water rises over the surface of the growing media add more media until the level of the nutrient solution and the growing media is the same. When the brain stops filling and all the pots have the right amount of growing media and nutrient solution, leave them soaking in the nutrient solution for 30mins to an hour.

After the pre-soak period, initiate the drain cycle on the timer by switching the toggle to seconds and turning the dial to the left. Once the drain cycle is finished, check the pH and nutrient strength in the reservoir. The pH may have changed so adjust if necessary. If the pH or nutrient strength has changed dramatically, empty the reservoir and change the nutrients solution.

Now you need to get a stopwatch ready to time the flood cycle. Start the flood cycle and the stopwatch (you are timing how long it takes for the ALL THE POTS to fill back to the maximum flood height). As soon as the maximum flood height is reached in all the pots stop the stopwatch and start the drain cycle.

With the time recorded you can now set your IWS system irrigations with an accurate flood duration. If you are using clay pebbles, add 1-2 minutes onto the time recorded on your stopwatch. This short period at the end of the flood, in which the pots stay filled, helps to saturate the clay pebbles and purge the pebbles inner core and outer shell of old nutrients. It will also allow the clay pebbles at the top of the pot to draw up water and nutrients by capillary action. It is not recommended that you hold your flood height for longer than 10 minutes as leaving your plants roots completely submerged in water for too long can cause poor root function and invite disease.

If you are using a mix with coco coir then the time recorded is your actual flood time. You do not need to add any extra time as your growing media has a fast capillary action and holds more water than pebbles alone.

Planting

Your pots should still be around three quarters full with the growing media at the same depth as the maximum flood height (refer to the left picture on the image below). When it comes to planting your young plants, you should plant them 1-2 cm into the growing media at the maximum flood height. This will mean that, during a flood cycle, the flood height will reach the bottom of the propagation block.

Please note: If you plant your young plants to deep into the pot your flood height will rise to high and saturate the propagation block causing poor initial root growth.

Once you are happy with the planting depth, fill the rest of the pot with more prepared growing media (refer to the right picture on the below image) .

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Setting the Flood Frequency

How often you flood the pots will be determined by:

  • The growing media.
  • The plant size and water requirements.
  • The environmental conditions.

The growing media

If you are using a growing media that does not retain much water, like clay pebbles, you will have to flood the pots with a high frequency. When using clay pebble and coir mixes, the WHC will be higher so flood frequency will be reduced.

Clay Pebbles

Through our own trials, 8-16mm clay pebbles come with our highest recommendation as the best growing media for flood and drain. We recommend using Grodan 3 or 4 blocks for preparing your plants to grow in clay pebbles. When using clay pebbles you must use the IWS Aqua Pots – these are large net pots that allow better flooding and enhanced root development. To prevent roots from chasing the water through the drain pipe, a root control disk is used in the bottom.

During a flood cycle with clay pebbles, the pots flood and drain quickly and between cycles the pebbles cannot hold onto large volumes of water. For this reason the flood frequency can reach a maximum of 1 flood every 1-2 hours when the plant is in full vigorous growth.

Your starting irrigation frequency depends on a number of factors; the size of your propagation block, the size of your plant and your grow room environment. Remember, your propagation environment will be quite different to your grow room environment. Most growers find that when moving their plants into their grow room, their water demand will increase due to higher temperatures and lower relative humidity (RH). If, for example, you have a large plant in a small block that has needed watering once a day at the end of the propagation period, then you should consider a flood frequency of once every 4-8 hours. If you have a small plant in a large cube that is not using much water, then 1 or 2 floods per day will suffice. It is important to make sure the block and clay pebbles are not drying too much, or staying too wet, between irrigations.

When you can see a noticeable increase in vegetative growth you can increase the frequency to once every 3-4 hours. As the plants get bigger and their demand for water increases, you should adjust the frequency to once every 2 hours. A lot of growers leave this as their maximum flood frequency, but some large plants in a hot and dry environment with a high water demand may benefit from a flood frequency of once an hour.

Remember that during each flood, water and nutrients are delivered to your plant and on each drain oxygen is pulled into the air spaces in the root zone. Therefore, when plants have fully established within the clay pebbles, more frequent floods mean more fresh oxygen around the roots. Please note: if your plants are not well established within the clay pebbles they will not benefit from frequent floods.

Coir

When using coir and clay pebble mixes, you must use the IWS Culture Pots. These pots have a net base which has been designed specifically for finer growing media. The bottom portion of the net pot should be filled with just clay pebbles. The rest of the solid pot should be filled with your mix of coir and clay pebbles.

The key to using coir in flood and drain systems is to not over-water. For the first 1-2 weeks after planting (the establishment time), your pots will need irrigating a maximum of once a day. This flood should be in the middle of your light period. Some growers find they get better results by hand watering from the top of the pot every 1-2 days for the first week, and then going onto using the flood and drain irrigation cycle once they know the plants roots are well established and ready for regular irrigations. This is an excellent approach for establishing your plants, but understandably, is sometimes impractical for growers with larger systems or for growers who run their light cycle during the night.

After the plants have established and vigorous vegetative growth has started, the plants water demand will increase. Around this time, check the moisture level of your mix before the irrigation or toward the end of your light cycle. If it is drying, you should increase your frequency to 2 times a day. The first and second irrigation should be equally spaced; e.g. if your using an 18hr light cycle, your irrigations should be at 6 and 12 hours.

These 2 irrigations are, in most cases, as much as they need, but plants that need to satisfy a high water demand may need irrigating 3 times a day during peak growth. An important phrase to remember when irrigating your coco coir and clay pebble mix is transpiration before irrigation – this means to wait for your plants to start using the remaining water in the growing media before giving them anymore. With this in mind, you should have your first irrigation at least 1-2 hours after the lights turn on.

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Hint: in most circumstances it is only necessary to flood the pots while the lights are on. Only during warm dark periods should you consider have 1 night time irrigation.

Environmental considerations

As with any hydroponic system, your nutrient strength and irrigation should reflect your grow room environment. For example; if the growing media is clay pebbles and during summer the room runs at 28C with an RH of 45%, then these hot and dry conditions will cause the plant to use more water and less nutrient. This means the nutrient strength should be set lower than usual to account for the nutrient strength rising in the reservoir. In these conditions the pots should be flooded once an hour.

But the same room during winter with a temperature of 26C and an RH of 60%, creates more favourable conditions that arent putting environmental pressures on the plants. This means higher nutrient strengths can be used and flood frequencies can be reduced to once every 2-3 hours. It is therefore extremely important to consider the effect that your grow room environment will have on your plants, and adjust your feeding strategy accordingly.

Maintenance

Avoiding root blockages

Because the flood and drain system fills and empties through the same tube, roots growing out of the pot can sometimes cause blockages in the pipe work. You should always use the copper root control disks provided to avoid this. You can also purchase the IWS Pot Filters which screw onto the inside of the outer pot and prevent roots growing into the pipes. Also, if you can get in amongst your plants, routinely turn the inner pot round 45 in the same direction every 2-3 days. This will make sure roots stay away from the tube and may also produce a more even growth pattern.

Checking for root blockages

If you suspect your pots or pipe work may be blocked, you can confirm it by quickly flooding the pot – do this by pouring 5-8L of nutrient solution into the top of the pot. If the solution drains away freely, it is ok. But if it sits there and takes a long time to drain, then you most likely have a blockage. Note: this technique only works well with clay pebbles. If your pot is blocked you should remove the inner pot and check the inlet/outlet tube for roots or debris.

Minimising system problems

Most system problems come about through not keeping a clean system. You must make sure your float switches in the brain pot do not become dirty or clogged with any growing media. Each time you refill the reservoir, a quick rinse with fresh water over the switches will help prevent problems. If you do notice sediment or debris in the reservoir or brain pot, remove or clean it immediately.

Common problems and solutions

Problem – My system fills but does not drain?
Solution  This is usually a problem with the pump in the brain pot. If the pump is vibrating but not pumping, it will be either air locked or blocked. Simply twist the pump so the inlet faces up, and if air bubbles are released and the pump starts working, then the problem is fixed. If it happens regularly, make sure the fill tube is not pouring water onto or near the pump. If it is, simply turn the tube outlet so it is pouring solution on the side of the brain pot and not splashing the surface of the water.

If the pump is vibrating in the brain pot and does not release any air bubbles when turned, it may be blocked. To service the pump you should turn the power off, remove the front off the case from the Maxijet 1000, and inspect the impeller and inlet. Remove any debris and replace.

If the pump in the brain pot is not vibrating and not pumping, then check the bottom float switch. If it is clean and not being forced open then you will need to contact Aquaculture returns/repairs department or IWS directly, as you may have developed a faulty pump, timer unit or float switch.

Problem – My system will not stop filling and my pots are over flowing!?
Solution – This is usually down to a siphoning effect that enables the pump in the reservoir to keep filling the brain pot at a reduced rate when the power switches off. Check that the anti-siphon valve in the reservoir is not underwater or blocked. The anti-siphon valve should be near the top of the reservoir. This allows air into the pipe when the pump is off to stop the water from flowing. If you do not have an anti-siphon valve you will have a small hole drilled in the pipe work coming up from the pump at the top of the reservoir. Check that this is not blocked.

If your pump is not siphoning and carries on filling the brain pot at full power then it may be down to a faulty top float switch in the brain pot. Make sure that the float switch is clean and free from debris. If it is clean and not being forced open, then you will need to contact the Aquaculture returns/repairs department or IWS directly as you may have developed a faulty timer unit or float switch.

Problem  Some of my pots are over-flooding!?
Solution  If you have an uneven floor and some or all of the pots are lower than the brain then you will get some over filling. You must ensure that all pots are at the same level as the brain pot, this is essential to how the systems works.

Problem  Why is the EC/CF rising rapidly in the reservoir?
Solution  Nutrient strength normally rises slowly in the reservoir as plants generally use more water than nutrients. If your temperatures are high (above 28C) relative humidity is constantly low below 50%) the rise in nutrient strength will be accelerated. These environmental conditions can cause a quick rise in nutrient strength between irrigations as the nutrients will be accumulating in the pots. Add more water to the reservoir to dilute the nutrient strength and consider reducing the nutrient strength by 0.2-0.4 EC units (2-4CF).

This can also be a sign that your flood frequency is too low and the growing media is being allowed to dry too much between flood cycles. Consider increasing the flood frequency.

Problem  Why is the pH rising rapidly in the reservoir?
Solution  pH will normally rise slowly in the reservoir due to normal nutrient uptake by the plants. If you are finding the pH is climbing rapidly and you are adding lots of pH down, it is normally due to the clay pebbles. Sometimes if you fail to wash the clay pebbles properly and do not pre-treat them with nutrient solution at the correct pH, then ph rise can happen in early growth. The pH will stabilise given time. If you are adding lots of pH down, we recommend you use a mixture of nitric acid and phosphoric acid, this will help the balance of minerals in the nutrient solution.

Problem  Why is the pH dropping rapidly in the reservoir?
Solution  pH drop can sometimes be a normal occurrence during the transitional phase from vegetative growth to flowering/fruiting. Adjusting back up with potassium hydroxide (ph Up) or potassium silicate (silicon) is recommended.

If the pH is dropping rapidly then it may be a sign of over-watering. If your flood frequency is too high and water is constantly saturating the growing media, then oxygen levels become depleted. This drop in oxygen will cause the pH to fall. Associated with over-watering, is root death coupled with an increased susceptibility to root diseases. Check that your growing media is not staying too wet between irrigations. If it is, consider reducing the flood frequency.

GROWING MEDIA

GROWING IN COCO COIR

Very popular with growers of all abilities, coco coir (also known as just coir) can help you to achieve great results with your plants in terms of growth, yield and quality. Here we explain what coir is and the benefits it gives you and your plants! We also detail how you can achieve great results when growing in coir.

What is Coir?

Coir (pronounced koy-r) is the term give to a range of natural products made from coconut husks. From the coconut husk there are main horticultural coir products that can be extracted – these are coir chips, coir fibre and coir pith (also known as coir dust).

Coir pith is the main constituent of most coir products available. It is very good at holding water while still providing adequate air space. This is due to the millions of micro-sponges that make up the pith; allowing it to hold up to nine times its own weight in water. Coir pith also has a unique cation exchange capacity which, when treated correctly, makes it perfect for hydroponics.

Coir chips and coir fibre are coarse coir products, and are often mixed with coir pith to lower the water-holding capacity and improve air-space and drainage. Coir chips can be purchased on their own for making custom mixes with coir pith, or can be used on their own in flood and drain hydroponic systems.

Benefits of Coir

  • As coir is derived from coconut husk, it is completely biodegradable. This makes coir an environmentally friendly hydroponic growing media.
  • Roots establish very well in coir due to the air-space and water-holding properties, but also because of the presence of naturally occurring Trichoderma – a beneficial fungus.
  • It can be used in a variety of systems including the AutoPot, Flood and Drain (when mixed with clay pebbles), hand-watered Pot Culture and Drip Irrigation Systems.
  • Coir is very easy to work with, and is suitable for beginners and professionals.

Dr Greens sell a few different bagged coir products: Canna Coco Professional Plus, Plant Magic Coco, VitaLink Coir Mix and VitaLink Coir Chips.

Canna Coco Professional Plus contains mostly fine coir pith with a small quantity of coir fibres. This creates a coir growing media that holds a lot of water, making it suitable for hand-watering and drip irrigation. When using it in flood and drain systems, it needs to be mixed with coir chips or clay pebbles. Some growers like to mix 5-30% perlite with Canna Coco Professional Plus to help with structure and aeration.

VitaLink Coir Mix contains a mix of 70% coir pith and 30% chips and fibres. This makes a coarse coir mix that holds less water and drains more freely; making it more suitable for frequently irrigated hydroponic systems such as drip irrigation and Autopots. VitaLink Coir Mix is also great for propagating young plants, and can also be used in flood and drain systems when mixed with more coir chips.

VitaLink Coir Chips are coarse and do not hold as much water as coir pith. These are used for mixing into other coir products to lower the water-holding capacity for frequently irrigated systems such as flood and drain. Coir chips are also used as a mulch on the top of pots and also as a layer on the bottom of the pot to aid with drainage.

Growing with Coir

What is Buffered Coir?

Before being washed and/or buffered, coir pith contains a lot of sodium ions. These are held tightly by the coirs unique cation exchange properties. Coir pith also contains high levels of potassium which is released slowly throughout its use. In order to make coir suitable for use as a hydroponic growing media, it is first washed with water to release some of the free sodium, and then it is soaked with a solution containing high levels of calcium. The calcium displaces the sodium from the coir, and after this soaking period the coir is again washed to remove the displaced sodium, leaving the calcium in its place. This whole process is known as buffering, and prevents the coir from holding onto calcium and magnesium, which are important nutrients for plat growth, and eliminates sodium toxicity issues.

Coir Specific Nutrients

As explained in the buffering process, coir preferentially holds onto calcium and magnesium, and also slowly releases its naturally occurring potassium. For this reason you should always use a coir specific nutrient like Canna Coco or VitaLink Coir which have elevated levels of calcium and lower levels of potassium. This will allow you to achieve optimum results from your plants. If you are mixing coir with other media, like clay pebbles, you can use hydroponic nutrients if the clay pebble content exceeds 65%.

Before using Coir

Coir does not contain a full range of nutrients for plant growth, so before planting, coir should be irrigated with a nutrient solution at a strength suitable for your plants until runoff occurs.

Checking the nutrient levels within your coir

Coir holds onto nutrients more so than other hydroponic growing media and just checking the run-off does not always give an accurate picture of the nutrient strength in the coir. The procedure below is known as a 1:1.5 extraction, and can be used to give a more accurate representation of what is occurring in the coir:

1.Take a 250ml measuring jug and fill it with 150ml of de-ionised or reverse osmosis water.
2.Remove small samples of coir from as many places as possible in the slab/pots.
3.Add the coir to the water until it reaches the 250ml mark.
4.Mix and allow it to settle for at least two hours.
5.Filter and measure the EC/CF.

Dr Greens tip:
Regularly checking the EC/CF of your coir helps to build a sound irrigation strategy.

Moisture of Coir

To achieve a higher level of air within your coir it should not be kept constantly moist. A good way to determine whether your coir contains the appropriate level of moisture is to lift your pots/slabs and determine the weight. If your pots/slabs are very heavy, they will be full of water. However, if they are very light, there will be very little or no water.

Irrigating Coir

Drip systems

Fewer, larger irrigations work best with coir. Drainage is improved and water and nutrient is best utilised if the frequency of irrigations is low and the amount of the solution is enough to get between 20 and 40% runoff. Typically, fully grown plants should need irrigating between 1 and 3 times a day depending on plant size. VitaLink Coir Mix does not hold as much water as 100% coco pith, so irrigations for fully grown plants should be 3 to 6 times a day.

Flood and drain

When using coir in flood and drain systems it is recommended that you mix it with clay pebbles or coir chips. Ready to use or homemade mixes of 40% coir and 60% pebbles are ok (ideally, 25% coir with 75% pebbles (or coir chips) is better). During a flood cycle the growing media becomes fully immersed in nutrient solution; making it fully saturated. And then after the drain cycle it can take quite a long time before it needs irrigating again. For this reason you should only need to flood a maximum of twice a day with 60:40 mixes and four times a day with 75:25 mixes for fully grown plants.

Hand watered in pots

Watering from the top of the pot is recommended, and you should water as and when the pots feel like they need it (do not water if the pots are heavy). As they reach one third to half of their original weight, it is time to water. As a guide, young plants in large pots should need watering every 2-3 days and fully grown plants should need watering once a day.

AutoPots

After planting into the AutoPot you should hand water from the top of the pot for the first 14-21 days. When doing this you should allow 10-20% of the solution you pour into the top to run out the bottom of the pot, this runoff should be discarded. This gets the roots established throughout the pot before you start constantly watering from the bottom. The AutoPot system delivers a continuous supply of nutrient solution to the pot. This can sometimes cause the growing media to become overly wet, particularly if the plants are small.

It is recommended that you mix 20-30% perlite or coir chips into fine coir when growing in AutoPots to help aerate the growing media and prevent over-saturation. Alternatively, use a pre-mixed coarse coir like VitaLink Coir Mix.

Reusing Coir

Coir products are often discarded after use, but this is very wasteful as coir can be reused up to 4 times! Good quality coir will keep its structure and its nutrient retention properties because it is very slow to decompose.

So how do you re-use coir?

After harvesting your plants, remove the coir form the pot or slab packaging and break apart with your hands or a hand trowel. Remove the crown of the stem and as many of the large roots as you can (do not worry about removing all the roots; they will break down over time during your next cycle and will not cause problems with disease).

Once you are happy that with the amount of remaining roots, put the coir back into the pot and wash through with water that is roughly half the volume of the pot so if you have a 10L pot, pour through 5L of water. Allow the coir to fully drain. After this pour through a nutrient solution at a suitable strength – roughly a quarter the volume of the pot. This process will remove the old nutrients from the previous crops, and replace with fresh nutrients ready for planting.

Dr Greens Tip:
When reusing coir, it is good to use beneficial microbes and enzymes through the plants life cycle to help break down dead roots and keep the coir and plants roots healthy and productive.

Please Note if you experienced nutritional, pest or disease related problems, it is best you do not reuse your coir as you may pass on the same problems to your new plants.

GROWING IN SOIL

Growing in soil has always been a popular method with indoor growers, not only due to its ease of use and low maintenance, but because it also caters for those growers who like to grow organically. This is a brief guide on what soil is and how to achieve good results using it.

What is soil?

Technically, soil is a naturally occurring deposited and decomposing matter on the Earth surface i.e. earth/mud/garden soil. What we sell and call soil is actually known as soil-less growing medium or a compost, but as most growers still call it soil, so will we.

Most pre-mixed soils you will find in grow shops will contain mainly peat – which has good water and nutrient holding abilities; making it a good growing media for plants. Peat is a natural, partially decayed vegetative matter that forms naturally in wetlands or bogs. All of our soils at Dr Greens contain mainly peat that has been treated to ensure that it is clean and free from pests and disease. Some cheaper peat based composts from large garden centres will often not be treated and can be of poor quality.

Benefits of growing in soil include:

  • Can grow your plants organically
  • Easy to use
  • Inexpensive to set up
  • Bio-degradable

Growing In Pots

Because of the nature of soil, the most practical way to grow your plants is using pots and watering by hand.

Propagation of plants should be carried out in Jiffy pellets, Root !t Rooting Sponges , or a suitable seed soil and small pot. Once the seed or cutting has established and has plenty of roots you should pot them into small 10-15cm square pots using a soil that has a low nutrient content. Once the plants are well established in the pots (1-2 weeks later) and you can see plenty of roots at the bottom of the pot its time to pot up.

Note: You should always establish a small plant in a small pot, plants in over sized pots will take a long time to use all the water from the soil and often stay too wet for too long.

Choosing your final pot size is important, generally to take an average sized plant to full maturity you need a pot size between 10-15L. For growing very big plants, 30L should be the largest you consider. The pots size should generally reflect the size you want the plant to finish at.

For example, your room size is 1m x 1m x 2m (L x W x H). If you are growing 20 small plants you would choose a pot size around 4-7L, if you are growing 4 large plants you would choose a pot size around 10-15L, if you are growing 1 or 2 huge plants you should use 30L pots.

How to Water

The key to successful soil growing is to only water your plants if they need it. Below is a guide on how to water your plants:

1.You should water from the top until water runs out of the bottom and collects in a saucer.
2.The plants should stand in this water for 5-10 minutes, if the water has soaked back into the pot repeat step 1.
3.Lift the plant out of the saucer and allow water to drain from the pot.
4.Empty and discard the water in the saucer.
5.The plant and soil is now fully watered, note how heavy the pot feels.

Repeat steps one to four when the pot feels about half the weight of a fully watered pot, this can take up to 3 days in early vegetative growth and as little as 1 day for fully grown flowering plants. It is important to not allow the soil to dry and shrink in from the sides of the pot.

The process above gets the whole root zone working throughout the entire pot. It is important to allow the soil to dry slightly between watering as keeping it too wet will damage the plants roots and overall health.

Using Liquid Nutrients

Your soil will need fertilising at some point during its cycle. If you are using a light soil with little nutritional content, you will need to start using nutrients after 7-10 days. If you are using a rich soil like you will need to add nutrients after 21-28 days. Generally, your plants will tell you when they need nutrients when the lower leaves on the plant start to turn a lime-green colour. Some plants need more nutrients than others and so looking at your plants and getting a feel for them is very important in soil growing.

Mineral or Hydroponic Nutrients

These should be used for soils at a low strength (CF10-14/EC1-1.4) to avoid over-fertilisation. These nutrients are generally cheaper to use with soil but easy to over fertilise. When using mineral nutrients every day, it is a good idea to use water only week to avoid nutrient build up.

Organic Soil Nutrients

At Dr Greens we recommend using organic nutrients. Organic nutrients tend to promote a better flavour and are more forgiving than mineral based nutrients. Organic nutrients also cause the micro-life (bacteria, enzymes, fungi etc) in the soil to proliferate which in turn helps to protect the roots and feed your plants. When watering frequently with organic nutrients it is a good idea to use water once a week to avoid over-fertilisation. When using organic nutrients you must be sure to use them within 24 hours of mixing as they do not keep well once diluted into water.

Soil and pH

For nutrients to be absorbed by the plants roots and for the soil to stay healthy the optimum pH is between 6.5-6.8. Soil is forgiving and has a good buffering capability but if you constantly water your soil with tap water higher than a pH of 7.5 you will slowly alter the soil pH and make some nutrients unavailable. If you do need to lower the pH of your water make sure you dont go any lower than 6.5 as it will damage the essential bacteria, fungi and enzymes in the soil. It is much easier for the soil to buffer the pH down rather than up.

To alter the pH of your tap water use pH down (phosphoric or nitric acid) or if you want to stay organic use Cannas organic pH down (citric acid). Adding nutrients to the water will lower the pH so if you are using nutrients always check and adjust the pH after adding them.

Troubleshooting / FAQs

Q > My Plants are wilting. A >Under watered or Over watered.

Q > The plants lower leaves are turning lime green. A >Under feeding.

Q > My leaves are dark green, curling down and have burnt tips. A > Over feeding.

Q > There are lots of little black flies buzzing around soil. A >These are fungus gnats a.k.a. Sciarid flies, can be a sign of keeping the soil too wet. The larvae eat the roots and can cause serious damage. Treat with beneficial Nematodes, Gnat Off and sticky traps.

Q > I have lots of small jumping insects in the run-off and on top of the soil. A > An insect called ‘springtails’, which are totally harmless.

GROWING ORGANICALLY

What does organic mean?

Other than the traditional scientific definition of containing carbon, organic growing is a term now used to describe a more natural, holistic approach to growing plants. This encompasses avoiding the use of chemical pesticides, fungicides and artificial fertiliser/ liquid nutrients.

Typically, in an organic garden, the grower will be using an organic growing media that is free from chemicals and is biodegradable along with dry or liquid nutrients and additives that contain plant or animal extracts, not refined mineral salts (chemicals).

How does organics work?

When you grow a plant using organic growing media and nutrients, there are some differences in the way the plant has access to nutrition in comparison to hydroponics.

In hydroponics, the plants are given nutrients that are already in an available form. This means the nutrients are taken up into the roots straight away.

When you water your soil with an organic nutrient, most of the elements that end up in and around the root zone cannot be taken up straight away by the plant. The elements need to be converted into a form that the plant can use – this is done by small microbes in the soil (bacteria, enzymes, fungi and protozoa) and the process is known as mineralisation. This means that the health of your soil becomes very important as it is a living system that nourishes the plant.

Organics Pros and Cons:

Deciding to grow organically is often a conscious choice to try and grow plants in the most natural way possible. But in reality, there are not many extra benefits when compared to hydroponic growing. Organic growing is slower than hydro – especially in vegetative growth – but it is a lot easier to maintain than a hydroponic system.

Controlling the nutrition in the root zone is more difficult because of the lag time between using the nutrients and them being available to the plant. This uncertainty with feeding is often counteracted by using nutrients every other watering or using water only once a week. If you ask an avid organic gardener, they will tell you that you develop a feel for what the plants need. It is this predictive interaction with the plants that a lot of organic growers learn to love and take pleasure in.

Organic Certification

There are many brands of nutrients and soils that will claim to be organic. To be certain that you are using quality products, make sure that they have certification from a recognised organisation. There are many organisations world wide that will approve a product as organic, but you must be aware that these organisations have different standards. Look for one of the following widely accepted organisations to be sure of its quality:

  • Soil Association – the UKs leading certification organisation
  • OMRI Organic Materials Review Institute, principal organisation in the USA
  • CU – The Control Union Certifications organisation, maintains worldwide supervision of input products that are used in organic farming.

Recommendations

At Dr Greens, we firmly believe that BIOBIZZ are the market leaders in supplying top quality products to produce organic crops. Certified by OMRI, their products are of premium quality and produce excellent results. We have many happy organic growers that have been using BIOBIZZ nutrients since we started selling them.

How Do I Grow Organically?

For more detailed instructions on how to grow using soil and liquid nutrients please refer to our Growing in Soil article.

What equipment do I need?

Pots and saucers, certified compost/soil, certified liquid nutrients, and lighting and ventilation as with any indoor garden.

5 Top Tips:

  • Check your soils nutrient content before starting.
  • Use a weak soil for propagation and a richer soil for potting on.
  • Do not use nutrients until your plants need them
  • Feed every other watering.
  • Use your organic nutrients within 24 hours of mixing.

NUTRIENTS

UNDERSTANDING NUTRIENTS

All plants require a range of different minerals for healthy growth. Usually, a plant absorbs the minerals it needs from the soil in which it is growing. However, with hydroponics you need to provide your plants with the minerals they require in the form of a nutrient solution. This allows you tight control over the minerals your plants receive.

Nutrients explained

Nutrients contain essential elements that are vital for plant growth. If these essential elements, as well as carbon dioxide (CO) and light, are made available to a plant, they can produce the compounds (food) the plant needs for normal growth. The most important elements are known as the macro elements. These consist of:

  • Nitrogen (N) – A plant uses Nitrogen for rapid growth and the development of foliage, leaves, flowers/fruit and seeds.
  • Phosphorus (P) – Phosphorus plays a major role in transporting glucose (plant food), stimulating root development, and promoting flower/fruit and seed production.
  • Potassium (K) – Like Phosphorus, Potassium promotes flower/fruit and seed production. It also helps to protect a plant from disease.

All plants require large quantities of the macro elements. During the vegetative cycle your plants will benefit from extra nitrogen, while more phosphorus and potassium is beneficial in the flowering stage. Different nutrients are used to ensure that your plants receive all the minerals they need in the right proportions at the correct stage of their lifecycle. There are two types of nutrient solutions available:

Grow mix:
A Grow mix contains high levels of nitrogen; you should, therefore, use this nutrient solution during your plants vegetative cycle.

Bloom mix:
A bloom mix contains high levels of potassium and phosphorus, so change to this solution when your plants start flowering.

Plants also require other elements known as secondary macro elements and micro elements.

Secondary macro elements are magnesium, calcium and sulphur. Micro elements (also known as micronutrients) are manganese, boron, copper, zinc and molybdenum. The table at the end of this document highlights why a plant needs each of these minerals.

Nutrient Solutions

Nutrient solutions are available in one, two and three-part packs. They are normally in concentrate form:

One-part nutrient solutions
One-part nutrient solutions are very easy to use and popular with beginners or growers who prefer the simpler method of feeding. The one-part removes the chance of incorrectly measuring the components of the two-part and three-part.

Two-part nutrient solutions
Two-part nutrient solutions consist of two bottles which are added (in equal amounts) to water in order to supply a full spectrum of elements to your plants. As the nutrients are more concentrated and specific, you can achieve very accurate feed levels for your plants at all stages of their life cycle. This helps to improve plant growth and health. Two-part feeds are the most popular nutrients as they are easy to use whilst delivering good nutrient levels.

Three-part nutrient solutions
Three-part nutrient solutions require three bottles to complete the nutrient formulation and are generally more suited to the professional grower. A three-part solution enables you to provide your plants with the most precise nutrient management throughout their life cycle even more so than a two-part. It allows maximum control over the nutrient delivered to your plants. Due to its more complex nature, three-parts are not suitable for beginners.

Maintaining the nutrient solution

Maintaining the nutrient solution involves keeping adequate nutrient strength, pH levels and optimum temperatures.

Nutrient Strength

The strength of nutrient is the amount of dissolved salts that a nutrient contains. Nutrient strength plays an important role in maintaining the health of a plant. If the nutrient is too strong, the leaves of the plant can become leathery, curl downwards or even burn at the tips. If the nutrient strength is too low, then the plant will turn yellow, stretch and become susceptible to disease. The strength of a nutrient solution is known as the conductivity factor (CF) or electrical conductivity (EC). These can be measured with a CF/EC meter, which allows you to maintain the required level for the stage of your plants life cycle.

pH Level

The pH is the measure of the acidity or alkalinity of a nutrient solution. A pH value of 0 to 6.9 indicates the nutrient solution is acidic, 7.1 to 14.0 alkaline. While a reading of 7 shows the nutrient solution is neutral. Ideally, the pH level should range between 5.5 and 6.5. If you allow the pH level to fall outside of this scope, it will affect your plants ability to absorb nutrients. This results in poor yields and slow growth rates.

Temperature

A good temperature around the roots can encourage root growth and nutrient uptake. Never let the temperature of your nutrient solution drop below 15C, as cold water will limit the ability of roots to absorb water and minerals, and drastically reduce yields. Similarly, a temperature too high above 30C  will starve your plants of the oxygen they need for healthy growth. Ideally, you should aim for a temperature of approximately 21C.

Additives

Additives are extra supplements that can be added to nutrient solutions to help the plant use nutrients more effectively.

This can promote growth and improve the general health of your plants. Additives can also encourage specific processes, such as rooting and flowering. Although theyre not essential, additives can be very beneficial in achieving the most from your plants.

Maintaining all of the factors discussed in this article should help your plants to grow strong and healthy. If you require any more information, please dont hesitate to contact us.

Please see below for a list of essential elements a plant requires:
Nitrogen (N) Macronutrient
Symptoms of Deficiency- Stunted growth and/or yellow leaves. Purpling along the veins on the underside of larger leaves.

Phosphorus (P) Macronutrient
Symptoms of Deficiency- Growth stunted, very dark green plant, leaves develop grey to purple dead patches.

Potassium (K) Macronutrient
Symptoms of Deficiency- Slow growth and /or yellow to brown margins on older leaves

Magnesium (Mg) Secondary Nutrient
Symptoms of Deficiency- Older leaves yellow; as the deficiency progresses, small brown patches develop in the yellow areas.

Calcium (Ca) Secondary Nutrient
Symptoms of Deficiency- Yellow/brown spots appear on the edge of leaves. These spots can also be surrounded by a sharp brown outlined edge. This often affects the older leaves first.

Sulphur (S) Secondary Nutrient
Symptoms of Deficiency- Small growth, all leaves turn yellow, reddening of the veins on the underside of leaves.

Iron (Fe) Micronutrient
Symptoms of Deficiency- Uniform yellowing of young leaves, while the veins remain green. Eventually, the whole leaf becomes bleached.

Manganese (Mn) Micronutrient
Symptoms of Deficiency- Yellowing between veins on young leaves, with brown patches forming along the veins.

Boron (B) Micronutrient
Symptoms of Deficiency- Younger leaves show a light yellowing/browning. A cluster of leaves develop in the same place. Leaf margins twist and leaves become brittle.

Copper (Cu) Micronutrient
Symptoms of Deficiency- Young leaves drooping, a wilted appearance, yellow to brown patches. Mature leaves may become bleached between the veins.

Zinc (Zn) Micronutrient
Symptoms of Deficiency- Older leaves develop brown patches in between the veins. Young leaves very small and/develop in a cluster in the same space.

Molybdenum (Mo) Micronutrient
Symptoms of Deficiency- Upward cupping of the leaves with mottling. Looks like nitrogen deficiency without the reddening on underside of the leaves.

ROOTS

If you want strong, vigorous plants and maximum yield, a healthy root zone is a must! Read on to discover how looking after the roots of your plants can help you to get the best from your growing.

Why are the roots so important?

The roots are responsible for absorbing water and nutrients that your plants need for healthy growth and development. Water and nutrients are pumped up to the leaves; which produce dissolved sugars and other substances that are pumped back down to the roots. These sugars supply the energy that roots need to grow. If any of the sugar is not used, the roots will store it as starch. The roots and their capacity to store starch determine how well a plant will grow and how much the plant will yield.

How can I tell if the roots of my plants are healthy?

If the roots of your plants look crisp and white with plenty of root hairs, they are healthy and will absorb the maximum amount of nutrients and water. If the roots develop brown tips or general browning, the problem is usually a lack of oxygen, and infection is likely to follow.

How can I ensure that the roots of my plants are healthy?

There are a number of factors that affect the health of roots:

  • Growing space – never grow in pots that are too small, because the roots of your plants will become overcrowded and circle in on themselves. This will adversely affect the amount of nutrients and water that the roots can absorb, reducing potential yield.
  • Oxygen – the roots use oxygen to convert sugar to energy and to transfer nutrients to other parts of your plants. The older parts of the roots towards the stem absorb oxygen and release carbon dioxide. Its important not to keep this part of the root system constantly wet. The bottom section can be kept constantly wet, provided that the water is well oxygenated. There are a number of products on the market that will provide the roots of your plants with extra oxygen. The most popular being, air stones with an air pump. Hydrogen peroxide can also be used to make slight increases in dissolved oxygen, and it also kills pathogenic organisms in the root zone. However, hydrogen peroxide also kill beneficial organisms and is not always compatible with all growth enhances or root boosters.
  • Temperature – to encourage healthy root growth and function, you should try to keep the temperature around the roots of your plants constant and warm. The roots are very active in the dark period. Ideally, aim for a day and night temperature of 20 C. Roots in a warm dark period (20 C) develop much better than those in a cool dark period (15 C).
  • Irrigation – the most important for plant growth. The less energy the roots use to absorb water and nutrients from their surrounding area, the more they can use to grow and transport nutrients through the plant. Ninety per cent of the water taken in by a healthy plant is transpired out through the leaves. If the roots are unable to extract water from their surroundings, your plants will struggle and may start to wilt.
  • Bacteria & Fungi – not all bacteria and fungi are detrimental to plant health. In fact, some are not only beneficial but essential! There are a number of nutrient additives and growth enhancers that contain beneficial bacteria and fungi that help to encourage plant growth and protect against disease.

Give your plants the start they deserve!

A lack of roots is the most common problem growers encounter when they come to transplant their plants into the growing system. To address this, a technique called air pruning comes with our highest recommendation.

When a root grows out of a growing media into relatively dry air, its tip is dried and killed. Once this first root is pruned, many secondary roots develop to replace it. These are then air pruned and replaced by even more roots. Basically, air pruning trains a root system with a very large quantity of young vigorous roots. The result is that the plant will establish more quickly. It is also expected that the plants will develop leaves and stems much faster than traditional methods.

However, there is one thing you must do to get the benefits of air pruning – raise the propagation/transplanting cells off the ground so that air can circulate around the bottom to kill the emerging root tips.

ENZYMES

During their life, plants are continuously making new roots and roots are constantly dying off. This process of dying off causes 2 problems. Firstly it can form a source of infection for diseases and secondly valuable space is taken up by the dead roots instead of air.

Enzyme products are used to break down these dead root cells. This creates more air space and enables the plant to absorb the nutrients that are released. Another advantage is that the substrate can be used again.

What are enzymes?

Enzymes are proteins that have a very special function; they can both build up and break down substances. Each enzyme has a specific function and generally speaking, they can only build up or break down one type of substance. If an enzyme does this, and it is not used up, it can stimulate the same reaction thousands of times.

Enzymes in cultivation

Enzymes that are used in cultivation must be capable of breaking down plant remains. Plant remains are made up of cells that are joined together with a kind of glue known as pectin. If you want to break down the remains, the glue between the cells has to be broken down and cells broken into pieces. A wide range of enzymes are needed for this, two of which are indispensable. The first enzyme dissolves the glue between the cells while the second enzyme breaks the cell walls into pieces. These enzymes are mainly involved in doing the rough work. Other enzymes are needed in addition to these two, but without these two enzymes an enzyme product simply will not work.

If you want to know if these enzymes are present in the product that you use, you can perform the following simple tests using items that you can buy in the supermarket:
Click here for the PDF 2 Step Enzyme Test
If the results of both tests are good, it means that both enzymes are present and that your product is actually capable of breaking down dead plant remains.

ROOT STIMULATORS

As its name suggests, root stimulator helps a plant to develop strong, healthy root systems. The stronger and healthier the roots, the healthier the plant. While many different types of products may claim root-stimulating features, a few types seem to work better than others.

Types

Several types of root stimulators may flood the shelves of your local nursery or garden center, and some may be quite different from the others. Some will boast B vitamins to aid with growth while others will simply offer a higher percentage of phosphorous than nitrogen or potassium. The Colorado State University Cooperative Extension recommends using ones that have hormone and fertilizing properties added. These often still have more phosphorous than nitrogen and potassium.

Hormones, Vitamins and Fertilizer

While vitamin B1 is often marketed as a natural plant root stimulator, the Colorado State University Cooperative Extension notes that research has shown this vitamin does not promote new root growth in plants in soil. Hormones and fertilizers, however, offer more to the plant than just root development and strength and, when used properly, can feed the roots, which in turn feeds the entire plant.

The Role of Phosphorus

Phosphorus is one of the big three when it comes to fertilizer. On the package of fertilizer, you’ll always notice a three-digit number separated by dashes; this is known as the NPK rating. These numbers represent the percentage of nitrogen, phosphorus and potassium, respectively. Phosphorus’ role in fertilization is large: It encourages a healthy, strong root system; promotes healthier buds, flowers and fruit; and can promote earlier maturity of various plants. It’s often a major component of root-stimulating products because it gives the roots a head start, so to speak. The roots start off with a food specially formulated for their strength.

Mycorrhizal Fungi

Some organic root stimulators involve mycorrhizal fungi to encourage healthy roots and plants. Mycorrhizal fungi are naturally occurring in soils; they form a symbiotic relationship with plant roots and are beneficial to almost every plant. The fungi help the plants’ roots absorb needed micro- and macronutrients, vitamins and water. Aside from some root-stimulating products, some natural fertilizers also incorporate this beneficial fungus.

PROPAGATION

PROPAGATION

Propagation is simply the creation of new plants. Many growers propagate using hydroponic techniques to benefit from early rooting and faster growth rates. This is possible because hydroponic growing media provides the root zone with easy access to water, nutrient and oxygen.

Propagation: Seed vs. cuttings

Firstly, as with any type of propagation, you need to decide whether you want to grow from seeds or cuttings. Generally, growers who propagate from seed do so because it gives them peace of mind that their plants will be disease and pest free. However, the main draw back with seeds is that the characteristics of plants you produce can be inconsistent. Whereas, with cuttings you are producing plants that are identical to their healthy parent, this is why cuttings are also referred to as clones. Other advantages of cuttings include:

  • Earlier flowering.
  • Improved plant stock.
  • Plant species which are more adaptable to climatic variations.

As growing from cuttings has so many benefits, at Aquaculture, we usually recommend our customers to use this method of propagation. However, for your first gardening venture you will probably have to start growing from seed. Our document Germinating your seeds should be of help. It is advisable to germinate several seeds at the same time. You will then be able to choose a mother (stock) plant from which you can take cuttings in future.

Taking cuttings

Setting up You will need the following items:
1.Propagation cubes/plugs.
2.Rooting hormone.
3.Heated or unheated propagator
4.Fluorescent lighting.
5.Sterile scalpel.
6.Spray bottle.
7.Nutrient.
8.Rooting stimulator.

This article explains how to propagate using rockwool cubes. However, the process is basically the same for all types of propagation, such as Root Riot cubes and Jiffy-7s.

The Mother Plant

You will have to grow your seedlings or cuttings under 18 hours of light until they are suitable to take cuttings from. This is usually when they are between 12-18 inches or have 8-10 internodes.

Label your seedlings with numbers or names so you can label your cuttings you take to correspond with the parent plant.

When your seedlings are ready, trigger them to flower by giving them 12 hours of light and 12 hours of darkness. Take the seedlings to full maturity to determine which shows favourable characteristics, i.e: quickest to root and/or best flower development.

While your plants are flowering, the cuttings will need to be kept in a vegetative state in a separate growing area with 18 hours of light and 6 hours of darkness.

The cutting with the same name/number as the plant with the most favourable characteristics should be kept as the mother plant.

Mother Plants can be grown in a variety of systems. We would recommend choosing a media based growing system as you will typically keep the plants for up to a year. Systems using techniques like NFT, bubblers (deep water culture) and aeroponics are more suited to short term crops.

The most popular method of keeping mother plants is using soil, or soil-less growing media in pots, which can be watered by hand or via and automatic delivery system.

Quality of cuttings

If you want strong healthy cuttings, it is important to consider the quality of the mother plant they are coming from. Make sure the mother plant is regularly trimmed to promote lots of side branches. This will give you more sites to take cuttings from. It is also advisable not to feed your mother plant too much. Overfed plants will produce thicker stemmed woodier branches and cuttings that will take longer to root.

The highest concentration of growth is concentrated around the bottom 1/3rd of the plant around the inner shoots. This is where you should take your cuttings from. Growers often refer to this section of the plant as the zone of juvenility.

Without stripping more than 25% of the foliage, take as many cuttings from the mother plant as possible. Also, it is preferable to use cuttings which have a few leaves. Cuttings with large leaves tend to be unable to absorb sufficient water through their stem. Those with thinner stems will also root much faster than cuttings with fatter stems.

Fluorescent lighting

As stated above, seedlings/mothers need to be grown under 18 hours of fluorescent light and 6 hours dark. However, once they are well rooted, you will need to switch to 12 hours of HID light and 12 hours of dark to initiate flowering/fruiting.

In the first week, before the roots have formed, cuttings will perform best with the fluorescent lighting unit positioned 25-50cm away from the propagator lid. When using HID lights for propagation you should only consider using 250w metal halide lamps. These should be positioned 1m away from your propagator. Higher wattage HID lamps will emit too much light and heat, and may result in your cuttings failing to root.

Rockwool propagation cubes

The main advantage of rockwool is that it holds more air and water than any other growing medium. Rockwool is also inert and sterile, and does not hold onto nutrient in any way. The roots are clearly visible and it is very easy to tell whether the cubes are moist or dry. They can be transplanted into larger rockwool blocks or any other hydroponic media with the minimum of fuss. Cuttings should take approximately 7-14 days to root. At this stage, you will need to transfer your cuttings into larger rockwool cubes or your chosen hydroponic growing medium.

A simple step by step guide to taking cuttings
1.Clean all work surfaces and equipment with a disinfectant.
2.Soak the rockwool cubes in a suitable nutrient solution for at least an hour. Shake the cubes to remove excess liquid. Plants need oxygen to root; rockwool which is too wet can prevent rooting and encourage disease.
3.As highlighted above, you should take cuttings from the base of the plant, around the outer shoots. Choose shoots which have 3-4 sets of leaves. With a smooth motion, cut at a 45 degree angle just below the internode (branch/stem join).
4.Immediately immerse the cut stems into a bowl of tepid water.
5.Remove the bottom leaves from the stem. Also, if the cutting has more than one large fan leaf, remove the extra.
6.With the scalpel, gently scrape the lower part of the stem. This will help initiate faster rooting.
7.Apply the rooting hormone to the cut stem or cube, as directed on the product packaging.
8.Gently insert the cutting into the cube. Lightly pinch the cube to hold the cutting in place.
9.After all the cuttings are inserted into the cubes, place them back in their plastic tray and position in a propagator.
10.Finely mist the cuttings with water, and then place the propagator lid on the tray.
11.Place the fluorescent lights over the propagator.
12.Give your cuttings 18 hours of light a day. However, if the air temperature drops by more than 4C when the light goes out, leave the lights on continuously.
13.Once a day remove the propagator lid and finely mist the propagator lid.
14.Roots should appear within 7-14 days. Once this is evident, the propagator vents can be opened.
15.If you wish to transplant the propagation cubes into larger rockwool blocks, simply pre-soak the blocks with a suitable nutrient and a rooting stimulator.
16.As with the cubes, its important that the rockwool blocks are not too wet. Insert the cubes into the larger blocks and place them onto a plastic tray or a surface on which the plants can be air pruned (see below).
17.Roots should appear on the bottom of the blocks within 2-7 days. After 10-14 days there should be loads of roots on the bottom of the blocks, at this point you can plant into your chosen hydroponic system. Do not be tempted to place your plants onto their system too early, only when there are an abundance of roots on the bottom of the blocks should you consider planting on.

Air Pruning

This is a propagation technique used to help promote a healthy root system. It involves placing your plants in rockwool blocks on a perforated tray or wire mesh. This should be positioned so air can naturally flow underneath the blocks. With this technique as the root tip grows out of the blocks it detects the dry air and dies back. This forces the root, still within the block, to branch out forming more roots. This means the roots concentrate their growth within the block. Eventually you will have a plant with loads of small root tips protruding from the block with a large mass of roots within the block. Soon after the plant is put onto its final system the roots extend from the block very quickly, getting the plant off to a great start. This technique is particularly useful for NFT although should be employed for all types of systems.

Using Heated Propagators

If your propagation area is too cold your cuttings and seedlings will take a long time to establish. If you have temperatures below 18C inside you propagator you will need to use a heating mat or warming pad underneath your propagator, or buy a new heated propagator. When using heat from a mat, pad or heated propagator it is recommended you use a 2.5cm layer of perlite or vermiculite, or a mixture of both, in you propagator tray. This will help spread the heat throughout your propagator avoiding hot spot areas.

Using Aeroponic Propagators

Recent advances in propagation equipment has led the UKs leading systems manufacturer Nutriculture to make available an affordable compact range of systems for propagating cuttings using aeroponics. With aeroponic propagation there is no need for any growing media, the main stem of the cutting is clamped in a sponge collar which is inserted into a net pot. This net pot is placed in the system where the stem gets a mist continuously sprayed around it. This promotes the ideal air to water ratio and cuttings often root within 5 days.

Once there are roots on the cutting you can transplant into a pot containing growing media. If you want to transplant into a large rockwool cube you can buy the large hole variations of the 3 and 4 blocks and fill in the space with perlite, vermiculite, coco coir or small clay pebbles. It is also possible to use small clay pebbles in the net pot, then place in your un-rooted cutting and place in the aeroponic propagator. The roots will still grow out quickly and the net pot can be placed straight into a Grodan 3 or 4 transplant block.

Troubleshooting/FAQs:

Q. My Cuttings wont root
A. This is a very common question and can be due to a number of factors.

  • The most common is the growing media you are using is being kept too wet. If you are using rockwool, after pre-soaking shake the cube to expel the excess water within the cube. When you spray your cuttings spray the foliage lightly not the cubes. Never leave water standing in the bottom of the propagator.
  • Cuttings will take a long time to root if they are too big. Try to take smaller cuttings around 3 (7-8cm) and remove the big leaves from the cuttings to reduce leaf surface area.
  • Check your rooting hormone is still in date.
  • Do not use strong nutrients to pre-soak cubes with, as this will inhibit root formation.
  • Make sure the temperature is between 18-24C and is kept fairly constant. If your temperature falls more than 4C between day and night, keep your lights on continuously to maintain a constant temperature.
  • Make sure you use a propagator and the vents are closed until roots appear.
  • Be patient, the average time to root cuttings is 7-14 days.

Q. My cuttings are wilting
A. This can happen soon after taking the cuttings but they should come back around. If they stay wilted its usually a sign that temperatures are too high (common problem in summer months). Reduce temperatures in the propagation area.

Q. The base of the stem on seedlings/cuttings brown/black/rotting
A. This happens when the growing media is kept too wet which invites fungal diseases to attack the plant, collectively know as damping off diseases. This is particularly problematic in warm and wet conditions.

PROPAGATION - RAISING AND CUTTINGS

In your mission to achieve the best possible results, producing strong and healthy cuttings or seedlings is absolutely essential. This is because the condition of your young plants will be reflected throughout the remainder of their life cycle. The stronger they are during the vegetative period. This maximizes the plant’s potential through flowering.

Media

At Dr Greens we supply a variety of quality media for you to successfully begin propagating. Regardless of the media you choose to begin with, you will always be free to transfer and plant into another form of media should you choose to.

Media Recommended Rooting Compound Benefits Points to Consider

Rockwool Cubes with Clonex
Fast rooting times and popular for rooting when transplanting to larger rockwool blocks.
Be careful not to over or under water

Jiffy Coco or Peat with Clonex/ROOT!T Rooting Gel
Easy to use – wont dry out as quickly as rockwool cubes and dont need to soak as long to prepare.
Slightly slower to root than rockwool /aeroponics.

Root Riot Blocks with ROOT!T Rooting Gel/Clonex
Fast rooting times and popular for rooting when transplanting to larger rockwool blocks.
Be careful not to over/under water.

Aeroponics

VitaLink Bioplus in water (or halfstrength VitaLink PlantStart)
Very quick rooting times and no media is needed.
Transferring to other media could induce higher transplant shock.

Presoaking guidelines:

  • Rockwool Cubes – soak for 4-5 hours in a solution of 2ml/L of VitaLink Bioplus, and 3ml/L of VitaLink PlantStart at a pH of roughly 5.5-6.0. Finally, gently squeeze or flick off any excess water.
  • Jiffy Peat Pellets – soak for 10 mins in solution of 2ml/L of VitaLink Bioplus at a pH of roughly 6.0. Finally, gently squeeze or flick off any excess water.
  • Jiffy Coco – soak for 10 mins in solution of 2ml/L of VitaLink Bioplus, and 3ml/L VitaLink PlantStart at a pH of 5.5-6.0. Finally, gently squeeze or flick off any excess water.
  • Root Riot – Optional. If you do choose to soak, use a solution of 2ml/L of VitaLink BioPlus and 3ml/L of VitaLink PlantStart at a pH of roughly 5.5 – 6.0. Finally, gently squeeze or flick off any excess water.

Feeding guidelines: For all the above media, soak for 4-5 hours in a solution of 2ml/L of VitaLink Bioplus, and 3ml/L of VitaLink PlantStart at a pH of roughly 5.5-6.0. Finally, gently squeeze or flick off any excess water. However for aeroponics media, simply keep the tank topped up with a solution of 2ml/L of VitaLink Bioplus and 3ml/L of VitaLInk PlantStart.
*Please note: Do not over water your cuttings. They like to be moist, not wet!

Propagators

Once you have determined the media you would like to root into, you then need to decide on the most appropriate propagator to match your requirements. The following table exhibits the range of propagators we offer which are all tailored to your budget; ensuring you get the most value for your money.

Propagators Overview

Stewart Un-heated Propagators
Very reliable and an ideal choice if youre running on a tight budget. (Sizes small and large)

Stewart Heated Propagators (2 versions Variable and Heat & Grow)
Excellent for heating root zones to promote quicker rooting times. The Heat & Grow is a more affordable plug and go propagator, whereas the Variable stands at a more premium price with its added ability to give greater control over the heat applied. (Sizes small and large)

X-stream Propagator
Very large propagation units that can house up to 3 trays of 1.5 Grodan cubes, and achieve a high output of cuttings. Lids can be purchased separately for makeshift propagation areas. (Sizes extra large)

X Stream Aeroponic Propagator
Regarded by many to be the ultimate way of taking cuttings quickly, easily and efficiently. There is no need for any media to root into, very little maintenance is required and the nature of the unit creates constant levels of adequate humidity for the cuttings. (Sizes Small, medium, large and extra large)

Hint If you are propagating or hardening off/growing plants on, it is more cost effective to heat the root zone with a BioGreen Heated Propagation Mat than it is to warm the whole growing area with a grow room heater.

Lighting

In order to root cuttings or raise seedlings effectively, you must provide them with the required lighting. This means using a specific propagation light that will provide constant gentle light and heat, as opposed to the HID lighting used for vegetative and flowering stages (which is generally too strong for fragile young plants). So whether youre producing hundreds of plants or raising a few seeds or cuttings, our range of lighting will meet all of your propagation needs and budget!

Light Overview/Benefits

Sunmate Grow (125W, 200W or 300W)
125W bulbs are ideal for cuttings and seedlings, whilst the 200Ws and 300Ws are also suitable for early vegetative growth. Available in a range of spectrums to suit your specific lighting requirements – Warm (red) and Cool (blue)

T5 Lightwaves 2 and T5 Lightwaves 4
Utilize the same high output bulbs as the budget lights, and are fitted into a high quality reflector to provide the best spread of light possible. The 2 comes in either 2 tube (48W) or 4 tube (96W) and the 4 comes in 4 tube (216W) or 8 Tube (432W). The 4 version is perfect for larger propagators such as the X-stream.

Sunmate Propagate
A small, convenient and low power consumption bulb. These are good to use over smaller propagators. (Available with 2 bulbs – each being 55W)

INDOOR GROW LIGHTS

Light is one of the most important factors to consider when growing plants. It is very simple – no light means no growth. In fact, as a general rule, the more light your plants have access to, the quicker they will grow and the more they will yield. The benefit of an indoor grow light is that it allows you to grow literally any plant, anywhere, anytime! However, to get the best out of your indoor grow light and growing it is helpful to understand the basic principles of light.

Spectrum

Anyone who has seen a rainbow will know that sunlight is made up of different colours. These colours of light can also be differentiated by their wavelength which is measured in nanometers (nm).

The human eye is most sensitive to light around the middle of the visible spectrum – between 500 and 600nm. Plants find wavelengths between 400 and 700nm useful for turning light into energy (photosynthesis), and this area is referred to as Photosythetically Active Radiation commonly abbreviated to PAR. While the human eye finds light at 555nm the most visible (thus more useful), plants find two distinct areas of the spectrum most useful the blue area between 400-460nm and the red area between 580-700nm.

Measuring Light

Lumens is a measurement of light intensity, and is often used to define the output from artificial lights. This is fine for lights to help us see in the dark, but becomes rather useless when measuring horticultural grow lights because lumens are measured according to what the eye is sensitive to. Using lumens is therefore not a correct representation of the properties of a lamp that are useful to plants.

Lux is often used by light-measuring devices and is simply a measurement of how many lumens fall on each square meter of surface. So an illumination of 50,000 lux is 50,000 lumens falling on each square meter. Lux measurements are useful for measuring intensity from grow lamps and can be used to determine an accurate height to position the light above the plants, or to check for lamp degradation. However, lux is still not a good measurement for determining the quality of light and how good it is for growing plants.

Professional growers and light manufacturers have switched from measuring light in lumens and lux, to photon count in the PAR area. Without going into too much detail, a photon is a particle of light. A blue photon has a short wavelength and does not have as much energy as a red photon – which has a long wavelength. The plant, however, is only interested in the number of photons (it does not use the energy in the photon for photosynthesis). A plant requires 8-10 photons to bind one molecule of CO2. So a blue 600W light produces less photons than a red 600W light and is less efficient for photosynthesis. However, you do need more than just red colours in your spectrum for a plant to grow healthily.

A device to measure photons is called a quantum meter. The total amount of photons – known as the photosynthetic photon flux (PPF) – from a lamp can be measured with a quantum meter to give you accurate data on the amount of photons per second coming from your lamp. Photons are counted in micromoles (mol) and in case you are interested, one mol is 602214150000000000 photons! The unit used for PPF is micromole/second (mol/s), and a good 600W HPS lamp will emit 1100 mol/s.

To summarise, if you have two lights and one has a higher lumen output, it is not an indication that it is better for growing plants. The most useful light output data is plant useable light measured in micromoles.

Day Length

The amount of light your plant receives in a 24 hour period is called the photoperiod or day length. Some plants use the photoperiod as a signal to know when to produce leaves, flowers or fruit. Using this signalling tool, indoor growers can alter the photoperiod using timers to control their lights and their plants. Long day lengths of 16-24 hours are most commonly used for vegetative growth, and short light cycles of 12 hours are used for flowering or fruiting. Most grow lights are too powerful for plug in timers, the solution to this this will be covered later.

Light and Environment

All lights produce some heat as well as light. When growing indoors this heat generated by the grow lights need to be removed using an extractor fan to keep the plants growing environment comfortable. If you position your light too close to your plants, the heat from the lamp may burn them. So, it is very important to correctly hang your growing lights.

Types of Grow Lights

There are two categories of lights commonly used for growing plants. These are fluorescent and high intensity discharge (HID).

Fluorescent Grow Lights

Fluorescent grow lights are more suitable for propagation and vegetative growth. They have good colour rendering properties (a high proportion of the light emitted is used by the plant) and produce less heat than HID grow lights (see below). This allows them to be placed closer to your plants to make the most of their output.

There are two types of fluorescent lights used for growing – Compact Fluorescent Lamps (CFL) and T5 lamps (aka tubes). CFLs are large energy saving lamps and have the electronics to ignite the lamp at their base. These can be screwed into a reflector or simply hung vertically above the crop. T-5s are the most efficient fluorescent tube light, and need separate electronics to ignite the lamps. These electronics are housed within T5 reflectors. Due to the size of the T5 tubes, they produce a very uniform level of light over a larger area in comparison to CFLs.

Compact Fluorescents are available in 150W and 250W, as well as a propagation lighting system utilising 2 x 55W PL lamps. T5s are available as 2ft 24W lamps and 4ft 54W lamps. These are available individually without a reflector or as an integrated lighting system with two, four or eight lamps.

Fluorescent lights are great for seedlings and cuttings, as plants at this stage do not need intense light. Both CFL and T5 are low intensity, so they need to be placed close to plants to be effective at promoting growth. If using fluorescent lights above propagators, do not place them too close as this will cause the internal propagator temperature to get too high.

The light emitted from a fluorescent lamp can vary depending on the lamp colour. Fluorescent lamps come in different colour variations differentiated by the Kelvin colour temperature scale. The Kelvin scale has become industry standard for differentiating commercial and domestic lighting, but is rarely referred to in horticultural lighting other than for fluorescent lamps.

Fluorescent lamps with a high Kelvin are mainly used for propagation or vegetative growth; these usually come in around 6400K. Lamps with a low Kelvin are used for flowering and usually emit light around 2700K. A mixture of both (1 x 27K for every 3 x 64K) is a good approach for vegetative growth , and the reverse (3 x 27K for every 1 x 64K) fruiting or flowering.

Top Tips:

  • Due to their lower light output, fluorescent grow lights should not be used instead of HID lights during the flowering stage. However, they are effective as supplementary lighting when hung in between your plants with CFL lamp hangers, or as side lighting with T5s.
  • All of our fluorescent lights can be plugged into a timer to control the photoperiod. A relay or contactor is not necessary.

HID Grow Lights

HID (High Intensity Discharge) lighting is the most efficient way to convert electricity into light and is the most popular type of horticultural grow light. HID grow lights are available in a large choice of wattages; the most common are 250W, 400W, 600W and 10000W with the 600W being the most popular option. A HID grow light is made up of three parts:

1.The Ballast which contains the necessary electronics to ignite and run the lamp.
2.The Reflector that holds the lamp in position and reflects light down to the plants.
3.The Lamp which can be either a High Pressure Sodium (HPS) or Metal Halide (MH).

Ballasts

A ballast or power pack is at the heart of a HID lighting system. There are 2 types of ballast available – standard electromagnetic ballast and the more recent electronic or digital ballast. Both deliver a surge of electricity at a high voltage to ignite the HID lamp. After ignition, the ballast then regulates the electricity being delivered to the lamp for safe operation. Electronic ballasts are around 3-4% more efficient than electromagnetic ballasts, run quieter and can have dimming functions to control the lamp power.

Reflectors

HID reflectors come in all shapes and sizes, but are all designed to do one job  reflect as much light as possible down onto your plants. The most efficient reflectors are about 95% efficient meaning of the original 100% light from the lamp, 95% is emitted by direct light from the lamp or reflected light from the reflector. Basically, even the best reflector will have around a 5% loss. A reflector should also help to create a uniform spread of light while avoiding hot spots of intense light. Some reflectors are sealed using a glass plate or tube and are air-cooled using an extractor fan to further reduce the heat emitted from the lamp and keep grow room temperatures down.

Lamps

Metal Halide MH

Metal Halide (MH) lights produce a lot of light in the blue spectrum. This colour of light encourages plant growth, particularly green, leafy growth and keeps your plants short and compact. MH lamps produce a broad spectrum of light (more so than HPS) and a small amount of UV which can help improve the quality of your produce. However, MH lamps are not as efficient as HPS, producing around 30-40% less micromoles.

High Pressure Sodium HPS

High Pressure Sodium (HPS) lamps emit mainly orange-red light. This band of light is best for fruiting and flowering plants but can also be used for vegetative plants with good results. HPS lamps are the most efficient grow light currently available and produce the best yields. Standard HPS lamps are slightly deficient in the blue spectrum; to supplement this you can use fluorescent lights or use a ratio of three HPS lamps to one MH lamp in the flowering period. Some HPS lamps are termed Dual Spectrum, which means that have an enhanced output in the blue spectrum. Dual spectrum lamps are touted as being an all-in-one veg and flower lamp, but their spectrum is still much more suited to flowering plants. Best results will be achieved using a MH lamp for vegetative growth and HPS lamp for flowering.

Top Tips:

  • If you want to supplement your HPS with extra CFLs, use the 6400K Cool White lamps as these will provide the blue light your HPS is missing.
  • Switching from a HPS to a MH lamp in the last 1-2 weeks of the plants life cycle can greatly improve the quality of your produce by enhancing essential oil production.

Relays and Contactors

When a ballast starts up, it draws a large amount of electricity for a split second so that it ignites the lamp. This spike of high voltage is enough to burn out a standard plug-in timer, so to successfully turn a HID light on-and-off automatically, you need to use a relay or a contactor. These devices use the timer as a signal, and draw the power through a 13-amp plug, rather than through the timer. One 13-amp relay can switch 1 x 1000W, 3 x 600W, or 4 x 400W HID lighting systems. Contactors are more heavy duty than relays and are used for larger indoor gardens with 4 or more 600W lights.

Other Types of Grow Lights

New technologies currently trying to improve horticultural lighting are light emitting diodes (LEDs) and light emitting plasma (LEP).

LEDs

Unfortunately, there has been a glut of cheap LEDs that have been launched in the hydroponics market over the years that have all over-promised and under-delivered. Many companies make claims that their LEDs are more efficient than HPS, but currently there are still no LED units that can produce yields that are close to comparable.

However, LEDs are a very promising area for supplementing light to change or steer the plants growth. The benefit of LEDs is they can be tuned to a specific wavelength to trigger a certain response or enhance a particular growth stage.

The common LED grow lights on the market that have a mixture of blue and red LEDs say they are tuned to match the two PAR peaks and drive targeted photosynthesis, but they are missing all of the other wavelengths (colours) that plants also need. Interestingly, the most promising LEDs to come to market during 2012 are the full spectrum LEDs that are designed to produce light across the whole PAR spectrum. However, the diode wattage and unit cost still means LEDs are not able to replace HPS lamps.

LEP

Light emitting plasma has come to market for the purpose of solar simulation. They produce a very broad spectrum of light, including UVs, which is close to natural sunlight.

LEP units can be used on their own for vegetative growth but are lacking in the red spectrum to produce a good yield of fruits or flowers. They are very good for supplementary light, particularly for adding in UV light to improve quality which is missing from most HPS lamp. The market leaders in LEP technology is Gavita Holland and we are sure there will be some great further developments in LEP lighting systems over the coming years.

HID Lighting – Helpful Tips

What lighting should I use in my grow room?

Your choice of grow light should be decided by the size of your growing area. Each type of HID grow light is suitable for a specified area. For guidelines on the type and number of lights you can put in your growing are see below.

Lamp Area Coverage:

  • 250 Watt = 0.25m2 – 0.5m2
  • 400 Watt = 0.5m2 – 1m2
  • 600 Watt = 1m2 – 1.5m2
  • 1000 Watt = 1.5m2 – 2m2

Hanging height – due to the heat that is emitted from HID lights, you should hang your lighting system according to size. The following is the recommended distance between the lamp and the plant canopy.

  • 250W = 30 – 40cm
  • 400W = 40 – 60cm
  • 600W = 50 – 70cm
  • 1000W = 75 – 100cm

Top Tips:

  • MH lamps emit more heat than HPS, so mounting heights will need to be adjusted depending on your lamp.
  • Use the back of your hand as a guide; if its too hot for your hand its too hot for your plants.

How Much Will it Cost?

To get the operating cost per hour for light, take the lights combined wattage, and divide it by 1000 to get the kilowatts used. Then multiply that number by the amount your electric company charges per kilowatt hour (you will find this at the top of your electricity bill). HID lights will use a little more than the stated wattage; a typical 600W system will use 640-660W. To find out the precise usage you can purchase a plug in power meter for less than 10, these will give you a digital reading of actual power consumption

PESTS & DISEASES

PEST PROBLEMS DURING SUMMER

Despite the enjoyable weather, summer tends not to be so pleasant for your plants, especially as harmful pests are more common during the warmer weather. Below we illustrate some of the most common pests and detail how you can prevent, indentify and eradicate them!

Spider Mites

Identification:

  • Resemble minute spiders.
  • Can be red or beige/brown in colour.

Damage:

  • Feed off the sap of your plants, causing leaves to turn yellow (can be spotted early as small white dots on the upper surface of the leaf).
  • Nymphs and adults also weave webs that often cover the plant completely. These webs serve as transport paths, which enable the mites to completely swarm the plant.
  • Lay white eggs on the underside of leaves.

As a preventative measure, Amblyseius Californicus natural predator in slow-release sachets are highly effective.

If damage is already done by the time you notice the spider mites, we recommend you spray your plants with an effective spray (Plant Vitality). Follow this up by releasing your predators.

Thrips

Identification:

  • Yellowy brown in colour.
  • Look like a small splinter of wood (up to 3mm in length).
  • The larvae of thrips are usually a lighter yellow/beige colour; they look like tiny maggots.
  • Leave behind silver-grey slug like patches/trails, and black dots (thrips excrement) on the leaves; a good indication that thrips have attacked your plants).

Damage:

  • When attacked, the plant is forced to use scarce resources to defend itself and recuperate from the damage done. This essentially leads to wasted resources; thus heavily deteriorating the overall quality of the plant.

Use the natural predator, Amblyseius Cucumeris, which is highly effective in controlling thrip populations.

If thrips have already built up a large population in your grow room, we would advise spraying your plants with alternate sprays of Pyrethrum, in addition to Neem Repel. This will kill off a large proportion of the adults and larvae. Follow this up by releasing your predators.

Sciarid Flies

Identification:

  • Also known as fungus gnats/fruit gnat or black fly.
  • Small black flies between 2-3mm long with veined wings.
  • Attracted to moist conditions around the root zone and rotting vegetation.

Damage:

  • Lay eggs in the growing media, which hatch into larvae that feed on your plants roots. This results in decreased root function and poor plant growth.
  • The larvae also spread viruses and disease, resulting in further damage.

You can use yellow sticky traps to monitor and catch the adult flies. Make sure you dont over water your growing media; sciarid flies like wet conditions. Lower levels of water in the growing media will make it difficult for larvae to survive.

Use Fungus Gnat Off with your nutrient solution to kill the larvae.

Top Tips – Prevention Better Than Cure!

Its always better to be pro-active instead of reactive when it comes to pests, which means you must not wait for the problem to occur before taking action. Creating an environment which stops pests from occurring in the first place will allow plants to grow freely and unhibited.

Here are some tips:

  • Spray your plants once with pesticide, before following it up with slow-release sachets of predators to prevent the pests from turning up.
  • Or use the HotBox Sulfume to release vaporised sulphur into your environment, which eradicates pests and disease. Please note: filtration needs to be off during use, so only use during the dark period.
  • Use of intake particle filters as an inexpensive way of cleaning incoming air, where airborne pests may exist.
  • Closely inspect any new plants, including cuttings you bring into your grow room. Pay particular attention to the underside of leaves. Always carry out these checks even if your new additions have been given to you by friends.
  • Keep your room clean, especially in between cycles. Products such as Room Clean are an effective way of sanitizing your growing area and equipment.
  • Empty, clean and change re-circulating tanks once a week for general maintenance.
  • If using rockwool blocks, cube caps can help to prevent pests.

PH AND EC CONTROL

WHAT IS PH?

pH is the measurement of acidity and its opposite, alkalinity in a solution. Neutral pH is 7.0 pH. Acidity measures below seven pH (7.0pH) with alkalinity measuring above it (7.0pH).

It is important to maintain a hydroponic nutrient solution at a pH level where the elements in the nutrient solution are consistently available to the plant. If the solution is too acidic or too alkaline it can cause lock up a situation which restricts certain elements essential for growth from being absorbed by the root structure.

Deficiencies in the required elements become apparent in the plants growth and can lead to crop failure. Additionally the pH of the water we drink is crucial to our health, the pH of a swimming pool is important, not only for our skin and eyes, but also for the efficiencies of sanitizers and pool equipment. Again the pH of the water a fish lives and breeds in is critical to its existence as certain species require a particular pH to survive.

The elements we add to a solution will either increase or decrease the solutions pH measurement. Only accurate measurement of the pH level will allow complete control of the outcome.

WHAT IS PH Chart Dr Greens

WHAT IS CONDUCTIVITY?

Conductivity is the total soluble salts contained within a liquid solution. Because pure water does not contain salts it has a conductivity measurement of zero. By adding soluble elements to the water, electricity is able to move through the solution giving it a conductivity rating.

So why is it important?

Using hydroponics as an example, different crops grow well at different levels of nutrient strength (Electrical Conductivity – EC or CF). Controlling this nutrient strength is all important in providing the best conditions for your crop. Without proper measurement your crop could fail from root burn brought on by too high a nutrient level, or death by natural causes from not receiving the vital elements they need to grow.