Milorganite (6-4-0 Organic Fertilizer)

Overview

Milorganite is a biosolids-based organic fertilizer (6-4-0) that has been a staple of the lawn care community for decades. It provides slow-release nitrogen and iron, which promotes dark green color without the risk of fertilizer burn.

How It Works

Made from heat-dried municipal sewage biosolids, Milorganite releases nitrogen slowly as soil microorganisms break it down. The iron content provides a dark green color response without excessive growth. It will not burn grass even if over-applied.

PFAS Concerns

Recent testing has identified PFAS (per- and polyfluoroalkyl substances) in Milorganite, leading to a significant shift in community recommendations. Many users have switched to dairy-based alternatives like Moorganite (Earth Sciences), which is made from dairy cow biosolids instead of municipal sewage and does not carry the same PFAS concerns.

Warm-Season Popularity

Milorganite remains especially popular in warm-season lawn communities, particularly for bermuda lawns in the Southeast. The slow-release nitrogen and iron are well-suited to warm-season feeding schedules.

Application

Apply 4 times per year at label rates. Safe to use in heat since it is organic and will not burn. Can be applied anytime grass is actively growing.