The growing medium is the material where plants develop their roots. This can be soil, a non-soil (soilless), or even water. It can be one single material or a mix of dozens of them. The growing medium must be chosen according to the aeration and water requirements and growth stage of the plant. Soil growing media is a range of constituents used includes peat, coir pith, wood fibers, bark, composted materials i.e. green waste, and bark. Mineral constituents like perlite, pumice, clay and vermiculite are also used.

Field soils are generally unsatisfactory for the production of plants in containers. This is primarily because soils do not provide the aeration, drainage and water holding capacity required. To improve this situation several “soilless” growing media have been developed.