Abstract: A mechanism for supplying a dilute fertilizer solution to a multiple number of growing plants includes an apparatus for adding fertilizer concentrate to a stream of flowing water, such that a relatively constant ratio of fertilizer to water is achieved. Pressurized water is diverted from a water passage into a container to achieve a fertilizer pumping action. A bag-like membrane in the container forms a pressurized water space that is in pressure contact with a separate fertilizer-containment space. Fertilizer concentrate in contact with the membrane is thus pumpd out of the container and into a stream of water flowing through the water passage. A constriction is provided in the water passage to achieve a pressure drop that produces the desired pumping action.