An apparatus that provides automatic mixing and distribution of granular or liquid fertilizers through an underground or portable sprinkler system, comprising a mixing container connected in-line with the sprinkler system's water delivery line or a regular garden hose connected to a portable or movable sprinkler, is herein disclosed. This mixing container provides a large lower portion which is accessed through a sealed and latched cover portion, through which granular-based lawn care chemicals are added. Incoming water then dissolves and mixes the chemicals, passes through removable filter media and exits the apparatus. This outgoing water is then routed to an underground sprinkler system or a portable hose-based sprinkler. A bottom valve can be opened to drain the apparatus and allow for cleaning. Additionally, the apparatus comprises an integral liquid fertilizer receptacle to automatically mix the incoming water with various liquid lawn care chemicals. Finally, the apparatus provides internal filtration to remove particulate matter therefrom the created fertilizer solution. The apparatus may be utilized at a header supply portion of a sprinkler system, part of an underground system, or connected inline between two garden hoses or a spigot.