Perlite is a magmatic rock that can bee used as growing medium for hydroponic growing. Due to its permeable nature, it lets water and nutrients circulate easily.

Other hydroponic growing mediums include Rockwool, Clay pellets, Coconut fiber, and Vermiculite.

Learn about perlite and growing hydroponically:

• Hydroponic Marijuana Growing Indoors

More grow medium definitions:

Grow medium | Soil | Seedling & Cutting soil | Hydroponic | Rockwool | Clay pellets | Coconut fiber | Vermiculite | Aeroponic