Plants are placed in net cups filled with an inert growth medium such as rock wool, expanded clay aggregate, sphagnum moss, or coconut coir. The net cups are suspended above a reservoir of water containing essential nutrients in solution. Only the root tips are allowed to touch the surface of the reservoir. As the plant grows and depletes the water level, a gap of moist air will form and expand between the water surface and the base of the plant. The roots in this gap become laterally branching "oxygen roots," and absorb oxygen from the air inside the container. By the time the water level is fully depleted, the plant should be ready to harvest. Thus, in one growing cycle, no additional replenishment of water or nutrients is needed beyond the initial application.
