A portable fertilizer root feeder for fertilizing plants which fertilizer root feeder operates on the principle of gravity and positioning of an applicator tube in order to regulate the flow of the fertilizer. The fertilizer root feeder includes a portable tank with a hose extension, a frame which supports the tank and which tank may be strapped to an operator's back for transport of the tank and a T-stake for making a hole in an area about plant roots such that the hose extension may be placed within the hole to deposit fertilizer. The invention operates without any mechanical parts and operates based on the principles of gravity.