A generally planar foundation pad is formed of a material such as concrete, or the like, and supports a framework defining a plurality of concentric circular paths stacked in a cylindrical array. A plurality of helical water troughs are supported by the framework within each of the circular paths. Water circulation apparatus is provided which pumps water from the bottom of each helical water trough to the top and selected intermediate portions of the water trough to produce a continuous circulation of water. The circulating water is combined with various nutrients and the nutrient and water solution is filtered as it is circulated. Each helical water trough is formed of multiple vertically stacked layers of the trough. As a result, a great length of water trough is stacked upon a small footprint of land. Each water trough is filled with a plurality of floating growing trays to form a continuous “train” of growing trays extending down the entire water trough. As the water and nutrient solution flows down e
