Milorganite Fertilizer is basically a bag of dried microbes! For 90 years Milorganite has been manufactured by the Milwaukee Metropolitan Sewerage District. This unique fertilizer is created from heat-dried microbes that have digested organic matter in wastewater. It feeds both grass and soil, plus it contains iron for greening - without staining sidewalks and driveways! Milorganite is a non-burning, slow release fertilizer that feeds for up to 10 weeks. It can be used on lawns, flowers, vegetables, shrubs, and trees. Try it when seeding grass, too! Sustainable. Environmentally friendly. 85% organic. 32 lb. bag covers 2,500 sq. ft.