Hydroponic Growing Mediums

m6In a traditional garden, the plant's roots grow in the soil. In hydroponics, a growing medium is used in place of the soil. The growing medium must provide anchorage and support for the plant's roots, as well as an equal balance between water and oxygen (not too wet, not too dry), both of which are needed by the plant's roots. The growing medium does not need to provide any nutrients, as they are all provided by the nutrients mixed into the water. The growing medium must therefore also be inert and sterile.

Ideal mediums are therefore chemically inert, sterile, porous, clean, don’t break down easily and are able to drain freely.
Many materials have been used as hydroponic growing mediums. These include: vermiculite, saw dust, sand, peat moss and, more recently, vermiculite, perlite, expanded clay pebbles and pumice stones.