Hydroponics is the technique of growing plants using a water-based nutrient solution rather than soil, and can include an aggregate substrate, or growing media, such as vermiculite, coconut coir, or perlite. Hydroponic production systems are used by small farmers, hobbyists, and commercial enterprises.

According to USDA: "Growing plants in water culture or sand culture without soil are procedures that have been used by physiologists studying plant nutrition and by other plant scientists for more than a century." (Growing Crops Without Soil. Beltsville, MD: USDA, rev 1965.)