Hydroponics is the art and science of growing without soil. The term was first coined by William F. Gericke around 1940 who took the word from the Greek. Gericke was among the first to grow plants on what he called "litter" suspended above a tank of water containing a nutrient solution.Since Gericke's time hydroponics has come a long way. Instead of Gericke's leaky wooden tanks, we now have leak-proof plastic tanks. Instead of Gericke's "litter," hydroponic growers use expanded clay balls, rockwool, perlite, sand or other support medium. In Gericke's day, he made his nutrient solution from manure with chemical additives, but today we can buy a concentrated nutrient solution optimized to suit the plants being grown.