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Hydroponics - an introduction

Hydroponics is the science of growing plants without soil, either through placing the plants in a container of solution (known as solution culture), or through using another medium such as gravel or sand (known as medium culture). Hydroponics is becoming more and more common, particularly in countries where the climate makes growing outdoors difficult. Hydroponics can be done indoors (and is more effective this way, as the climate can be controlled), and ensures a high yield. For arid, dry climates or areas with short growing seasons hydroponics thus holds the solution. 

Although the technology has been around for a number of years, it is only recently that hydroponics has begun to take over the growing industry as a viable and cost-effective way of producing high quality plants. Many of the vegetables, fruits and herbs available in supermarkets are grown using hydroponics – particularly salad greens and herb seedlings. Not only does hydroponics offer growers a guaranteed yield – a controlled climate without soil eliminates weather damage (flooding, drought, or winter and summer extremes), soil contaminants (metals, diseases, and residual chemicals), and pests (indoor growing means infestations are almost non-existent); but the science also uses less water than outside irrigation techniques and is therefore more cost-effective and friendlier to the environment. 

Hydroponics aren't just for large-scale producers either – schools use hydroponics kits for teaching purposes, keen gardeners use hydroponics in green houses, and communities or people living in remote areas may use hydroponics to supplement their normal food supply. The science is a popular one, due mostly to it’s obvious environmental, productive and cost benefits, and the improvements in technology will only continue to bring in interest.

Methods

There are several different methods that can be used to grow with hydroponics technology. Your budget, size of setup, availability of mediums, and desired yield will ultimately determine which method you choose to implement. Of course some hydroponics techniques require more involvement from the gardener than others, and this may also affect your final choice. 

Solution culture is one of the two main methods of hydroponics. Solution culture has two sub-divisions, static solution culture and continuous flow solution culture. Static solution is the technique of placing a seedling or cutting in a container of solution. Continuous flow solution, meanwhile, uses the Nutrient Film Technique (NFT) – a shallow stream of water continuously flows over the roots (generally the water is re-circulated), allowing the roots access to air as well as water and thereby encouraging growth. 

Medium culture, meanwhile, has any number of separate techniques, as ultimately it depends on the medium you choose to grow your plants in. Sand, gravel, rockwool, diahydro (sedimentary rock), expanded clay (sometimes called hydroton or leca), coir (coco peat), perlite (volcanic rock), vermiculite (volcanic rock), brick shards and polystyrene packing peanuts are all popular choices. In all mediums the emphasis is on providing silicon to promote plant growth, and ensuring that there is no soil in the medium that could potentially lead to a contamination or disease outbreak. 

Both solution culture and medium culture rely on nutrient solutions (water with artificially added nutrients) to encourage the growth and health of the plants. The solutions must stay above a certain level of mineral content to be effective, and can be tested with an electrical conductivity meter to ensure this happens. Some of the most common solutions include combinations of cations (positively charged ions) of calcium, magnesium and potassium, and anions (negatively charged) or nitrate, sulphate and phosphate.

Getting started

If you’re ready to take the plunge into hydroponics, there are several fun and easy ways to get started. If you are looking to begin a commercial or large-scale enterprise or growing scheme, it is recommended that you get in contact with a hydroponics hardware supplier who may be able to sell at wholesale (and therefore cheaper) prices. If you instead want to take up hydroponics as a hobby or addition to your garden, there are several great companies both online and within the UK who supply starter kits and accessories. 

GroWell is probably the most highly regarded name in commercial hydroponics hardware supplies, and they have an extensive range available online. Their kits are a great way to get everything you need to begin. Their hobby size kit is ideal for experimental hydroponics, teaching a class, or perhaps as a gift for that scientifically minded friend. The Hobby kits can grow 2-4 plants in an enclosed space (such as a cupboard), and come with Nutrient Film Technique (NFT) technology; a lighting system and hanging kit; a tank, pump and sheeting; a spreader mat, transplanting cubes and cutting cubes; and the absolutely vital nutrients and pH test kit. Larger kit sizes available will grow more plants – the kits come in 8-10, 16-20, and even larger quantities of plant-growing capabilities. In general, the more wattage available in the lighting and the larger the tank, the more plants you will feasibly be able to grow. Kits also come in hard or soft water varieties.

Common questions

Whether you are starting up, experimenting with a new technique or technological break-through, or researching the science of hydroponics, there are several common questions which you may find yourself asking along the way. 

*What is ‘aeroponics’ and is it better than ‘hydroponics?

Aeroponics is the technique of growing plants in an air or mist environment. Some people consider aeroponics to be a solution culture hydroponics technique as it relies upon the supply of water and nutrients through sprays or mists. While aeroponics may not be suitable for some plants, it is becoming more popular as water supplies become scarce. 

Do I need a grow-room or grow-box?

One of the accessories available for purchase from most good hydroponics hardware suppliers is a self-assembly grow-room tent. If you are interested in growing a larger number of plants than can be contained in a cupboard or enclosed space, grow-rooms or grow-boxes are a good alternative. They allow the climate to be controlled and thus guarantee the success of the crop. 

What sort of irrigation should I use?

If you are using a medium culture growing technique you will need to consider whether to use sub-irrigation or top irrigation to maintain the flow of water and nutrients to your plants. Ultimately the irrigation you choose should be determined by the water absorption capacity of the medium you are growing in – in other words, if the medium absorbs all the water and nutrients, sub-irrigation is preferable as it guarantees the water gets to the roots of the plant and is not absorbed by the medium. 

What sort of containers should I use? 

Depending on the scale of your enterprise you may choose to use plastic tubing or containers, or glass jars. Which ever you decide upon, it is important to note that the containers need to exclude light from reaching the roots, solution, and medium – if light does get through, there is a possibility for algae growth in the solution, which would thereby destroy the crop.

This article was originally published on the web on hydrogreen.co.uk however that website is defunct at May 2015. The copyright is with the original owners of hydrogreen.co.uk
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