A chemical dispensing apparatus includes a housing that is connectable to a source of water, such as a standard garden hose, and an internal space in which is disposed a rotatable container containing a quantity of chemical concentrate to be mixed with the source of water as it flows through the housing and is dispensed from the housing from a sprinkler head or misting nozzle. The flow of water through the housing is directed to imping vanes on the rotatable container, such that the container is rotated as water flows through the housing. In an alternative embodiment, the vanes are replaced with an electric motor. Rotation of the container cause the chemical concentrate to dissolve which is then mixed with the water before it is dispensed through the sprinkler or mister.