Hydroponics is a method of growing plants using mineral nutrient solutions, in water, without soil. Terrestrial plants may be grown with their roots in the mineral nutrient solution only or in an inert medium, such as perlite, gravel, mineral wool, or coconut husk
Hydroponic Solutions - Vol. 1 presented by Growing Edge 130 pages Hydroponic growing tips. More than 250 of your questions answered.