Hydroponic gardening is becoming more popular these days as people start to understand how hydroponics works. There are more diy websites on hydroponics and Youtube videos on how to build hydroponic systems to grow plants and vegetables. Hydroponic gardening uses no soil, it is soil-less. The media used are listed below with a brief description of each one.
Coir or shredded coconut husk is a great medium for hydroponic gardening. Coir has excellent water holding ability, better the peat. Ability to retain nutrients against leaching Good drainage / aeration. Less shrinkage. Retains physical properties longer.
Rockwool - is a form of silica that is heated until it melts and is then blown and spun into a fiber. The fibers are compacted and cut into slabs and cubes and then treated with a wetting agent.
Leca - is expanded clay balls. It isn't good for wick method but lends itself very well to drip, ebb and flow, support for plants grown in deep water culture. It gives fairly good support for larger plants, and allows for great drainage and air for the root zone.
Vermiculite - is a form of mica and is also light and absorbent. In fact it has many times the absorbency of perlite. It does tend to break down and isn't as stable as Perlite. It is mostly used in wick methods. It also needs support for larger plants. A mixture of 50% Perlite and 50% Vermiculite makes a great mixture to start seedlings, cuttings, seeds configured in a wick method.
Perlite - is made from mined silica and expanded by high temperature to many times its original mass, it is light in weight, absorbent and gives the root zone plenty of oxygen. Perlite is used in wick, drip, and even ebb and flow methods. It cannot hold up a large plant and it is necessary to give plants growing in Perlite support from above. It is important to rinse Perlite thoroughly to plant in it. Perlite comes in several sizes small too large.
Rockwool - is a form of silica that is heated until it melts and is then blown and spun into a fiber. The fibers are compacted and cut into slabs and cubes and then treated with a wetting agent. Rockwool is used alot in commercial hydroponic growing of vegetables in greenhouses.