Abstract: An assembly for supplying a nutrient solution, such as water, to plants supported on a greenhouse bench, which retains the solution supplied thereto from a reservoir disposed immediately beneath the bench. A main source of liquid, such as water, is supplied through a main valve to a float-operated valve within the reservoir for maintaining a predetermined level of the solution within the reservoir. Also included is a fluid line interconnecting the bench and a pump disposed within the reservoir whereby the solution may be pumped to the bench through a check valve in the line and which prevents reverse flow. Also attached to the line is a solenoid actuated drain valve which drains the solution from the flooded bench and back into the reservoir.