A riding lawn mower mounted drop spreader apparatus is used for spreading a granular material while mowing. The spreader includes a hopper for holding a quantity of a granular material to be dispensed with a control gate which controls the amount of material distributed while mowing. An auger located in the hopper has a drive motor which can also be controlled by an operator of the mower. The hopper has a mounting frame for mounting the hopper and agitator mechanism on a rear chassis region of the lawn mower. An operator can visually observe the amount of material distributed by observing the mowed path behind the mower during use.