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Hydroponic Medias

Plant roots die on exposure to sunlight and so it is necessary to have something that the plant can get it's roots into. In hydroponics this is called a hydroponic medium, or medias (plural). The mission of hydroponics to find optimal growing conditions has uncovered a few basic rules for the requirements that a hydroponic medium should meet (other than keeping out light, which is number one priority). These are in no particular order:

Firstly, it should be sterile. Pests and diseases are spread in soil or other medias that are not sterile.

Secondly, it should be inert. Food is supplied at the optimum dose via a nutrient solution, so there should be no food supply in the growing medium itself.

Thirdly, the medium has to provide this solution and an adequate oxygen supply to the roots. Some medias (like expanded clay) do not hold water, but are ideal for use in continual flow systems, or systems that have large quantities of nutrient flowing past the roots. Other medias will hold a lot of solution, so have to be watered infrequently. Root aeration is important because oxygen is absorbed by roots and greatly speeds up plant growth. A good oxygen supply to the roots will also stave off root rot.

Customers come into the shop and ask 'What is the best medium to use?'. There is no best medium, but some are more suited to certain systems than others. This really is a matter of looking at your own circumstances and weighing up your options. Perlite is not a good idea in a flood and drain system because it floats. Cocopeat is not generally a good idea in any recirculating system because coco particles will flow back into your reservior, get stuck in your pump and possibly cause it to fail. The advice given on these pages about 'which medium should go with which system' is a rough guide only. Experts in hydroponics may have other ideas, but for people relatively new to hydroponics this advice is quite sound.

The Hydroponic Warehouse
Shop 3, 73 Pickering Street, Enoggera
Brisbane QLD Australia
(Opposite Enoggera Bowls Club.)
Phone: +61 (07) 3354 1588 Fax: +61 (07) 3354 3622