Beginners Overview and Guide to Hydroponic Gardening

26 mins read

Centuries before the time of Christ, Egyptian records show that plants were being grown in the Nile without the use of soil and Marco Polo describes floating gardens in China in the thirteenth century. Over the past one hundred and fifty years, a great deal of research has taken place into soil-less cultivation, particularly during and after the Second World War when there was a need to produce food for military personnel stationed in areas where it would be otherwise impossible to raise fresh produce. Nowadays, in so-called developed countries, a great many plants are produced hydroponically. In Europe, for instance, around 80% of tomatoes and 90% of cucumbers come from hydroponic systems, as does much of the huge production of flowers in Holland.

What is Hydroponics

When a plant is grown in soil, it will mature according to the quality of soil, the frequency of watering and feeding and the amount of light and heat it receives. Other aspects, such as pest and disease control, may then be considered where applicable, along with individual requirements for the type of plant. Since soil already contains nutritional minerals, plants grown in soil can only be fed nutrients or fertilizers at a rate that will not leave a build up of nutrient salts that harm the growing process.
When a plant is grown Hydroponically, it simply means that the plant is grown in an inert medium, that is to say in a medium that holds no nutritional value of its own, to which nutrition may be added at enhanced but acceptable levels. In this way, it is possible to influence the growth of the plant so that it realizes its maximum potential. Plants require water, light, oxygen and nutrition. The Hydroponic gardener is not forcing the plant to do anything un-natural, he is just providing these factors in a growing environment that provides them at maximum possible levels.

Nutrients and Water

There are many plant nutrients available and the choice can be confusing. Most are produced on a simple NPK formulation some are produced using a more complex formulation and or have built in growth enhancers.
Water quality can make a considerable difference to the quality of the food supplied to your favourite plants, and the first and most important factor of choosing your nutrient is “ are you in a Hard or Soft water area? “ ..this is important as Hydroponic nutrients are produced in either Hard or Soft water formulations, which will partially adjust your waters pH level to suit. Even so, some pH adjustment will still be necessary with the aid of pH Up & Down acids.
A quick ‘in house’ test to see if you are in a Hard water area is to look in your kettle to see if there is much limescale at the bottom!..if there is, then it is likely that you are in a Hard water area. We recommend asking your local growshop or contacting your local water board just to be sure.
To create the perfect nutrient mix, you may wish to consider Reverse Osmosis which will strip 99.9% of impurities from your water supply.

Successful Propagation and Cloning

A. Starting from Seed:

  • Soak RockWool SBS Tray in lukewarm water or a weak and slightly acidic nutrient solution. We highly recommend FORMULEX as a conditioning solution for RockWool as it will stabilise the pH and supply a full profile of mineral nutrition to the young plant. Use it at the weakest strength mentioned in the instructions. Allow plenty of time for RockWool cubes to take up water. Stand it to drain.
  • Insert seeds carefully into the holes marked out on top of the cubes. Don’t push them in too far, just enough to hide seeds. A few strands of RockWool should be teased over the hole to ensure that seeds are covered.
  • Place RockWool SBS Tray in a warm place. Light is unimportant until the seedlings begin to emerge but MUST be supplied as soon as they do Ideal germination temperatures for most species are in the range 20 – 25 o C. These temperatures should be maintained as constantly as possible during the germination period. Check the moisture level of the RockWool EVERY day. If you just squeeze a corner of a cube, water should come to the surface. If it does not then you should give the whole tray a light sprinkle of lukewarm water.The biggest mistake with RockWool is to keep it too wet and this usually occurs through poor drainage. NEVER let your RockWool stand in a puddle of water, always allow free drainage underneath the tray.
  • Once your seedlings begin to appear you will need to give them plenty of light, a warm sunny windowsill might do but a greenhouse or artificial lights will be best. Fluorescents are very suitable for small seedlings or clones. It is still important to maintain temperatures in the mid twenties for as much of the day as possible. Keep checking your RockWool cubes for signs of drying out.
  • Once your seedlings begin to show roots at the bottom of the RockWool cubes it is time to think about planting them out. Just lift the little cubes carefully from the tray Your new seedlings are now ready to plant into soil in the normal way OR to be cultivated further in RockWool. More information about RockWool can be found here.

B. Starting from Cuttings (Clones):

If you already have access to healthy plants that display desirable characteristics it is possible to clone new plants from them. These new plants will be genetically identical to the stock plant and, provided that the environmental conditions are constant, the new plants should perform exactly as their parent did.

, Beginners Overview and Guide to Hydroponic Gardening, ISMOKE

  • Soak RockWool SBS Tray in a weak acidic nutrient solution (pH 5 / 1.0 mS). FORMULEX is ideal for this. While the RockWool is soaking, you can be selecting material for cuttings. Most species are propagated best from softwood tips. Selected material should show signs of healthy vigorous growth. Stems should be thick and firm and foliage should be dark green.
  • Remove selected piece from mother plant with sharp scissors, taking care to cut plant at least 10 mm below the point where the final cut will be made. Final cut should be made with a sterile scalpel or clean sharp razor blade just below a node or leaf junction. A diagonal cut is preferred as it allows more plant tissue to come into contact with the rooting compound.

The rooting compound we recommend is Clonex Rooting Gel. Pour a small amount of Clonex into a small container for immediate use. Do not dip cut tissue into the container.
Immediately dip the cut tissue into CLONEX, ensuring that all cut surfaces are well covered with CLONEX. Wipe off surplus CLONEX against the side of the small container. Do not return any of the unused Clonex back to the original container as this might contaminate the remaining gel.
Insert cutting into hole in top of RockWool cube. It is very important not to push it in too far, just enough to support it in an upright position.

Why choose NFT systems?

Nutrient Film Technique systems are some of the most productive available, and they are often the chosen method of commercial growing. Plants are grown in an inert medium (usually RockWool cubes) and placed into a light-tight and shallow channel. Nutrient solution is continuously circulated, flowing over the roots up to 24 hours per day. The name of this growing method was so coined in order to stress that the depth of the liquid flowing past the roots should be very shallow in order to ensure that sufficient oxygen is supplied. This growing technique is generally favored by gardeners that wish to grow multiples of small to medium sized plants that will yield heavier than their size would usually determine.

Why choose Flood & Drain systems?

Often these types of systems are called Ebb & Flood. The plants are usually grown in pots with their roots supported by an inert medium ( usually expanded clay pebbles) the pots sit in a plastic tray which in turn sits above a reservoir filled with nutrient solution.
A pump in the reservoir is connected to the bottom of the tray. When the pump turns on, the tray fills with water. When the water level reaches a pre-determined height, through the use of the overflow fitting, the water falls back into the reservoir. When the pump turns off, the water runs back down through the pump into the reservoir.
Most growers choose to control irrigation with a timer. A typical schedule would involve several short one-hour water cycles per day, but the duration and frequencies of watering cycles varies from one system to another and is dependent on the crop, the plant size and environmental conditions.
This growing technique is generally favored by gardeners that wish to grow high density medium sized plants, while providing a well oxygenated root system.

Why choose Dripper systems?

Drip systems are the most widely used Hydroponic systems in the world. They are commonly used in commercial facilities for growing long term crops like tomatoes and peppers. Drip systems provide plenty of aeration (more than ebb and flow) because plant roots are never totally submerged, but are never allowed to dry out.
Drip systems operate very simply. A pump has tubing connected to it which then branches off to smaller tubes feeding many plants. Nutrient solution is dripped onto the base of each plant where it then trickles down through the grow media (inert or soil based) and into the roots and finally drains into the reservoir where it is re-used, unless ‘Run to waste’ is employed ( dosing a precise amount of nutrient which does not re-circulate).
This growing technique is generally favored by gardeners that wish to grow small to large sized plants, while providing a precise and controlled feeding program.

Why choose Deep Water Culture systems?

The hydroponic method of plant production by means of suspending the plant roots in a solution of nutrient rich, oxygenated water. Traditional methods favour the use of plastic buckets with the plant contained in a net pot suspended from the centre of the lid and the roots suspended in the nutrient solution. An airpump or aerator is placed in the bucket or pod, which delivers a constant and very high level of oxygen, leading to explosive root production.
This growing technique is generally favored by gardeners that wish to grow medium to large sized plants.

Why choose Aeroponic systems?

Aeroponics is an exciting improvement on hydroponics that has been shown to greatly increase all aspects of plant growth, especially where Propagation is concerned.
The roots of the growing plants are suspended in the air in a suitable channel, where they are misted by high pressure sprayers. The sprayers break the nutrient into small particles and saturate the roots. The levels of oxygen in the water are kept high by the constant circulation of the water; this leads to explosive root production and enhances every aspect of plant growth. The nutrient run-off is then returned to the tank for re-circulation.
This growing technique is generally favored by gardeners that wish to grow small to medium sized plants or produce exceptionally healthy Clones where Aeroponic Propagators are concerned.
Aside from Propagators.. please be aware that if you are in a Hard Water area, an Aeroponic system may require extra vigilance and maintenance.

Growing FAQ

Q: What temperature should my growroom be?

A: The ideal temperature is around 26-28c (75-80f) for the vegetative cycle and a couple of degrees lower in the flower or fruiting cycle.

Q: What humidity level should my growroom be at?

A: The ideal humidity level is around 50% (40-60% range is fine). If your humidity level rises in the flowering stage, then mould spores have a greater chance of harming your favourite plants. Ideally you should try to lower the humidity level in the last weeks of flowering to around 40-50%.

Q: How much ventilation is required in the growroom?

A: To calculate how big a fan you will require: Simply multiply the length x width x height of your growroom in mtrs which will give you the cubic capacity of your room ..and then multiply that value by either 20 or 30 which is the minimum and maximum air changes required per hour for optimum ventilation in your growroom.
For example: A growroom measuring 2mtrs x 2mtrs x 2mtrs = 8mtrs cubed x30 air changes an hour = 240mtr cubed per hour will need to be ventilated ..As a rule we recommend buying a slightly larger capacity fan than you need to allow for summer increases in temp and or using a Carbon filter.
(30 air changes per hour are ideal for optimum ventilation).

Q: How much lighting is required in the growroom?

A: The industry rule of thumb is: 400-600w per square metre, but this can differ depending on growing technique and the height of a growroom and the height of the plants desired.

Q: What will happen if I use too much or too little lighting?

A: If too little light is used then your plants will have a lower yield and will visibly be weak and vine like. If too much light is used, then you will also have a reduced yield due to the plants inability to cool down and visible scorching may occur.

Q: Should I use a pH meter?

A: Yes or at the very least use a liquid pH test kit. Keeping the pH of your nutrient solution within the ideal range will help your plants to take up essential elements contained in the nutrient solution.

Q: What is the ideal pH of my nutrient?

A: In a re-circulating hydroponic system the ideal range is between 5.8 -6.4, keeping it around 6.0 will be fine. For soil grown plants the ideal pH range is between 6.4 – 7.0, closer to 7.0 is optimum.

Q: Should I use a Conductivity meter?

A: Ideally Yes. It is possible to grow without a conductivity meter but you will have no idea how strong the nutrient solution is when ‘topping up’ etc. This can lead to toxic nutrient feed problems which will harm your plants.

Q: What is the ideal Conductivity (E.C/C.F) of my nutrient?

A: The strength of your nutrient mix is very much dependant on the age & variety of plant and at what time of year it is (seasonal adjustments). Experience will give you personal guidelines that suit your growing best.

General guidelines:

  • Young vegetive plants: E.C 1.2 – 1.6 or C.F 12 – 16
  • Established vegetive plants: E.C 1.8 – 2.2 or C.F 18 – 22
  • Established flowering plants: E.C 1.8 – 2.4 or C.F 18 – 24

Q: What if the Conductivity is too high?

A: Every aspect of plant growth will slow down, and visibly you will see the plants begin to burn out in the form of brown spots or brown, curling leaves.

Q: What if the Conductivity is too low?

A: The plants will be weak and pale and yields will be lower.

Q: What is Hard water?

A: Being in a Hard Water region means that your water supply is heavily laden with Calcium and Magnesium. This leads to pH instability in most cases and requires the grower to use a Hard Water formulated nutrient which will already be buffered to take this into account. A grower in a Hard Water region will generally have more pH maintenance of the nutrient solution and occasionally can experience Calcium and Magnesium feeding problems.

Q: What temperature should my nutrient solution be?

A: The ideal temperature range is between 18-22C. Low temperatures cause a slowing in all aspects of growth, and higher temperatures will starve the solution of oxygen and can lead to root rot problems.

Q: How often should I ‘dump’ my nutrient solution?

A: Ideally you should dump the tank every 7-9 days. Obviously there will be times when this is not possible, but every two weeks should be the absolute minimum. If you do not dump the tank, then a build up of salts left behind from the nutrient can cause serious problems for your plants.

Q: Should I aerate the nutrient solution?

A: Always, especially in hot summer months when the heat will deplete the oxygen in the solution much quicker than other times of the year. Keeping oxygen levels optimum will enhance every aspect of plant growth and yield.

Q: Should I use RO water (Reverse osmosis?)

A: If possible yes, although it is not essential. Tap water (especially in Hard Water areas) has many contaminates and salts which are used to chemically clean the water. Some of these contaminates are useful but most are not. By using RO water you will have the basis for creating the perfect nutrient solution, which will enhance every aspect of your plants growth cycles and yield abilities.

Q: Why are the plants wilting?

A: Usually this is due to a lack of oxygen or the plants being attacked by a disease. Contact us for more in-depth information and for recommended products to prevent or cure this from happening.

Q: Why are the roots brown and smelly?

A: This is usually the symptom of Pythium disease attack. But more commonly it is caused by over-watering the plants or in-adequate drainage of a system. Contact us for more in-depth information and for recommended products to prevent or cure this from happening. A healthy root will always be slightly off-white in colour and will not smell like it’s rotten!

Q: What causes leaves to turn yellow/brown/purple?

A: Unfortunately there are many reasons for this happening: Nutrient & pH related problems; Temperature related problems within the growroom or the nutrient tank; Disease or pest attack. We recommend contacting us as soon as you see the problem so that we can guide you through the process of elimination.

Q: What is the creamy brown mould rotting my flowers?

A: Unfortunately this will usually be Botrytis or Grey mould. Keeping your growroom humidity down to a reasonable level during flowering, and using air movers will help to avoid this problem. But most gardeners will experience it at some point or another and will learn to deal with it by being extra vigilante in the last few weeks of flowering and or using suitable fungicides to help keep it under control.

Q: Are there any pests that will attack my plants?

A: Yet again, unfortunately Yes. The most common growroom bugs are Spidermites, Whitefly, Thrips and Sciarid Flies (Fungus gnats). All if not dealt with as soon as they are visible, can lead to severe plant growth problems and even death. We recommend looking here for pest solutions.

This article is brought to you by Lkdj2003and our friends over at THCTalk.

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, Beginners Overview and Guide to Hydroponic Gardening, ISMOKE