Hydroponics
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Hydroponics is a system of growing plants by feeding them on a water and nutrient mixture, and not in soil.
There are different ways of doing this and most smaller plants and vegetables (including flowers) can be grown and because we give the plants exactly what they need they grow faster and produce better-looking leaves, roots, flowers and tastier fruit.
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Plants can be grown closer together and in smaller spaces indoors or outdoors with much less work than conventional farming. Hydroponics uses less water because the water is recycled in a closed system and doesn't seep away. There is a lot of information available, so you won't have to experiment too much to get good results.
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Plants grow better in a hydroponic system and are not exposed to insects, moulds and microbes in the soil, so they don't need to be sprayed with insecticides or treated for most diseases.
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A way to hold or support the plants
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Water with a mix of nutrients dissolved in it
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A way to get the nutrient mixture to the plant roots
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Light
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Ways of checking the nutrients in the water
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GROWING HYDROPONIC VEGETABLES AND HERBS AT HOME
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If you have some space available at home with exposure to sunlight (a back yard, balcony or sun-room) with an electrical connection for your water pump, you can grow hydroponic vegetables, flowers or herbs.
You can choose a kit to suit the space, whether it is indoors or outdoors and according to the amount of sunlight. You will need to consider the following factors when deciding on what kind of system to install and what to plant for the best crops:
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All plants need light to grow. We prefer to grow veg in sunlight (because it's free), but some plants grow better in full sunlight and others do better in the shade.
You can grow plants under artificial lights, but normal light bulbs won't work - you'll need growing lights: High Pressure Sodium (HPS), High Intensity Discharge (HID), Metal Halide (MH) or Light Emitting Diodes (LED's - use only LED's with a mix of red and blue light, green light isn't used by plants)
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When you start your hydroponics system, you'll need to fill it with water to the right level and ali the right amount of nutrients for the plants you are growing. After this, you may have to top up the water level from time to time.
Once a week you should ali nutrients and check the pH (acidity) of the water.
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Hydroponic nutrient mixtures contain macro-nutrients (bigger quantities) and micro-nutrients (tiny amounts or "trace elements").
The NPK value tells us how much Nitrogen (N), Phosphorous (P) and Potassium (K) is contained in a nutrient mixture. As a plant grows and develops, it will need different levels of these MACRO ELEMENTS.
Trace elements (also called MICRO NUTRIENTS) are very small quantities of specific elements in a nutrient mix and your plants also need these: Iron (Fe), Zinc (Zn), Copper (Cu), Boron (B), Chlorine (Cl), Manganese (Mn), Nickel (Ni) and Sulphur (S).
These levels will usually be indicated after the NPK values on the nutrient packaging.
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MAINTENANCE FOR A HEALTHY CROP
The water is in hydroponic systems will probably be reused over and over, even in a "run-to-waste" system water can be collected and filtered for recycling.
It is important to keep the water and nutrient mixture flowing and to check the plants and nutrient levels in the water to make sure your plants get everything they need to grow beautifully.
As time goes by, the plants will draw nutrients out of the water and you'll be aliing more, so the nutrients not used by the plants can build up and affect your crop, so you'll need to check the water once a week, or if you notice something wrong with the plants.
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If the pH level of your nutrient mixture isn't right for the plants you are growing, the plants won't grow well - so you need to measure and adjust the pH of your water once a week, or more often while you adjust it.
The pH level is a measurement we take to tell us how acidic or alkaline a solution like the water with dissolved nutrients is. Ph values closer to 0 are more alkaline, those closer to 14 are more acidic - pH 7 is neutral (not alkaline or acidic).
Only ever ali small amounts of pH-UP or pH-DOWN to your nutrient solution (water and nutrient mix) to fix problems with the pH level in your system - big adjustments can damage your plants.
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OTHER MEASUREMENTS: EC, PPM & TDS
To help your plants grow at their best you will need to give them everything they need, so you must keep the levels of nutrients correct - but how do you tell what the plants have been taking out of the water?
Using an EC meter to measure the Electrical Conductivity (EC) of the water, tells us how concentrated the nutrients are in the water (how much nutrient is still dissolved in the water). You will then have to ali nutrients or water to the system to reach the right levels for the plants you are growing: tomatoes grow best at EC levels of 2.2 to 2.8 µS/cm³ (Micro-siemens per centimetre), lettuce at 0.3 to 1.4 µS/cm³, peppers at 2.0 - 2.7 µS. You'll have to find out which levels are best for your plants.
Another way to check nutrient levels is to test the water with a TDS meter, which will tell you the amount of Total Dissolved Solids (TDS) are in the water. This is usually measured in Parts Per Million (PPM).
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The roots of the plants might be supported by a growing medium such as sand, gravel, perlite, coir (coconut husk fibre) - these are all porous materials that let the nutrient solution flow through, but some will hold on to more of the liquid than others.
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In Drip Systems, the hydroponic solution is pumped to the plants by drip lines - a number of thin tubes that feed similar amount of nutrient mix into the growing medium at the root of each plant. Plants can be placed in individual containers or larger grow beds. Oxygen must be mixed into the water using an air pump and airstone in the reservoir before it is sent to the plants.
In a to-waste setup, the waste water is collected in another tank after passing through the growing beds or containers. This water can be reused but must be checked and ph and nutrient levels adjusted first.
The drip system can also be run on a recovery basis, where the water is automatically collected after flowing through the growth beds and returned to the reservoir to pass through the growing beds again. In this case, the water must be checked for pH and nutrient levels at regular time slots.
Most vegetables can be grown in a drip-feed system, including tomatoes, brinjals, cucumbers, green peppers and squash as well as herbs.
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In Deep Water Culture (DWC), plants are placed in a raft that floats on the water and the roots of the plants hang part-way into the water, so they can get some are and take nutrients from the water. Oxygen still has to be mixed into the water using an air pump and airstone, but there is no need to move the water if it is deep enough.
The plants can be put into little plastic baskets in a specially made plastic tray, or large holes can be made in polystyrene and the plants held in place with woolly material so the plants don't break the rafts as they grow.
You might have to tie the corners of the raft down so the growing plants don't turn the rafts upside down.
The DWC or raft system is great for growing lettuce, leafy green vegetables, green peppers, strawberries and herbs.
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FLOOD & DRAIN SYSTEMS (ebb and flow)
Flood and drain systems work by pumping nutrients dissolved in water into a large growing bed and then draining the liquid back into the reservoir - this can be done on a timer, or by using an automatic syphon system that automatically starts draining the liquid quickly as soon as it reaches a certain depth. Draining the tank allows the roots of the plants to breathe.
The growth bed can be filled with a stone, or a lighter medium like coco moss or vermiculite that will hold on to more of the liquid.
(A bell syphon will use gravity to suck liquid out of a tank or growing bed automatically when it reaches a certain level.)
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FILM TECHNIQUE SYSTEMS (nutrient film technique)
In Nutrient Film Technique (NFT) systems the nutrient rich water keeps slowly running down furrows or channels (or pipes) on a gentle gradient. The plants are placed in cups or trays with their roots growing in the water. The plants grow more roots above the water level so they can breathe. An airstone and air pump can be used to mix oxygen into the water in the reservoir if needed.
The water is automatically recovered and fed back into the reservoir, so the pH and nutrient levels must be tested at regular times to make sure the plants grow strong and healthy.
Leafy green vegetables such as lettuce grow very well using the NFT system.
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Aquaponics is when plants and fish are cultivated together, the water from a flood and drain hydroponic system flows directly into a fish tank, the water and waste from the fish are then pumped into a settlement tank for recovery and testing. It is then returned to the reservoir that feeds the plants.