The cultivation of plants in a liquid nutrient solution instead of soil.

A carefully prepared aqueuous solution of all the nutrients required for healthy growth is used, usually in conjunction with an inert medium (such as sand or gravel) which provides support for the plant's root system.

On a small scale, the solution is simply poured over the substrate and the excess allowed to drain into containers for re-use.

On a commercial scale, this is done by an automatic pumping system in which the solution is monitored to maintain nutrient levels and acidity.

Hydroponics enables crops to be grown in arid regions, or where the soil is infertile or polluted / toxic. However, its comparatively high costs are a limiting factor, and hence almost all hydroponics work is with high value plants such as vegetables and flowers.