ABSTRACT
The hydroponic growing of plants is soilless culture-the growing of plants without soil.. A substitute "soil" medium is used, such as a mixture of peat, vermiculite (expanded mica), perlite (heated pumice) or styrofoam chips. These media are commonly sold at garden centers under the name of "potting mixes" for houseplants. However, soilless culture can also include the use of pure sand (of volcanic origin, not of sedimentary, seashell origin), coarse vermiculite or perlite alone or mixed, fir bark or other non-soil materials. Recently, rockwool (similar to
fiberglass insulation (but having more rigid structure) has become very popular for commercial growers and can be easily adapted for use by the backyard gardener.
