Hydroponics is a unique and interesting way to grow fruits, vegetables, herbs, and flours. It can be used to describe one of several ways that plants can grow without soil.
Mediums for growing plants hydroponically might include containers filled with gravel, sand, vermiculite, crushed rock, styrofoam, cinder, expanded shale, or hadite.
It may seem like a futuristic type of gardening, but the concepts of hydroponics have been around since at least the 16th century. It's thought the hanging gardens of Babylon were grown hydroponically. The Aztecs were using hydroponics to grow many of their fruits and vegetables because they were forced into marshy land that had no soil for growing crops.