Abstract: A hydroponic growing system consists of an elongated growing unit disposed above a supply tank which normally contains a nutrient solution. The growing unit contains pearlite or another solid particle growing medium into which the plant roots extend. Periodically nutrient solution is pumped into the growing unit and then air is pumped through the nutrient solution and growing medium in the growing unit to aerate the plant roots which extend into the growing medium. Thereafter, much of the nutrient solution is permitted to drain from the growing unit to the supply tank with some of the solution adhering to the growing medium to nourish the plant roots.