Hydroponic gardening is a method for growing plants, flowers, and vegetables without soil. The term hydroponics is comes from the Greek words hydro (water) and ponos (labour). So as the name suggests in hydroponic gardening the plants are grown in water rather than soil, or, rather a nutrient solution to be more accurate.
A variety of techniques exist for growing hydroponics. The two main types of hydroponics are solution culture (where plants are grown in a liquid mineral nutrient solution only) and medium culture (where plants are grown in an inert medium, such as vermiculite, gravel or Rockwool). Most plants can be grown hydroponically, however some thrive better than others.
According to Wikipedia,
“The earliest published work on growing terrestrial plants without soil was the 1627 book, Sylva Sylvarum by Sir Francis Bacon, although he died in 1626. Water culture became a popular research technique after that. In 1699, John Woodward published his water culture experiments with spearmint. He found that plants in less-pure water sources grew better than plants in distilled water. “
In the 19th century researchers found that plants absorb essential mineral nutrients as inorganic ions in water. Under natural conditions, the mineral nutrients in the soil dissolve in water, and the plant roots absorb the mineral nutrients. The soil itself is not essential to plant growth as long as the required mineral nutrients are introduced into a plant’s water supply.