Scotts Weed & Feed vs Milorganite: Which One Should You Use?

Yes, you can use Scotts Weed & Feed and Milorganite in the same growing season, but not in the same application. The typical rotation is Scotts Weed & Feed once in early spring (March or April) when broadleaf weeds are actively growing, then Milorganite three times across summer and fall (June, August, October) for routine feeding without weed pressure. Do not apply both within 4 weeks of each other; the lawn cannot use that much nitrogen at once and you waste the second application.

Milorganite is better than Scotts as a routine slow-release fertilizer, but Scotts is better when you also need weed control. Milorganite's 6-4-0 NPK delivers ~8 to 10 weeks of steady feeding from a single application, has near-zero burn risk, and is OMRI-listed organic. Scotts Turf Builder (the non-weed-and-feed variant) at 28-0-3 delivers more nitrogen faster but is synthetic and carries some burn risk. For routine feeding alone, Milorganite wins. For weed knockdown plus feeding, Scotts Weed & Feed wins.

No, Milorganite does not kill weeds. Milorganite is a pure fertilizer; it contains no herbicide active ingredients. A common myth is that Milorganite's iron content somehow suppresses weeds, but the iron is at a level that helps grass color, not weed control. If you have active broadleaf weeds, you need a herbicide like Scotts Weed & Feed, Ortho Weed-B-Gon, or a selective post-emergent. Milorganite plus a separate weed control is also a valid combination.

Wait 4 to 6 weeks after Scotts Weed & Feed before applying Milorganite. Both products contain nitrogen, and stacking them within a few weeks gives the lawn more nitrogen than it can use; the excess leaches into groundwater or runs off as waste. The Scotts Weed & Feed nitrogen pulse lasts about 4 to 6 weeks, after which the lawn is ready for the next feeding. This timing also lets the broadleaf herbicide in Scotts finish its work before adding more nitrogen pressure.

Milorganite is cheaper per 1,000 square feet applied. Milorganite costs about $4 to $6 per 1,000 sq ft per application; Scotts Weed & Feed runs $8 to $12 for the same coverage. Over a typical 4-application growing season on a 5,000 sq ft lawn, Milorganite costs about $100 to $120 while Scotts comparable program runs $200 to $250. If you only need to feed (no weed pressure), Milorganite is significantly cheaper.

You should not put Milorganite and Scotts Weed & Feed down in the same application. Both add nitrogen, and applying them together gives the lawn far more than it can absorb, so the excess is wasted or runs off as pollution. There is also no reason to mix them: the herbicide in Scotts works best applied on its own to a dry lawn, while Milorganite is a slow-release feed for a weed-free lawn. Space them out instead. Apply Scotts Weed & Feed first when broadleaf weeds are actively growing, then wait 4 to 6 weeks before your first Milorganite feeding.

Scotts Green Max is a fast-release synthetic fertilizer with added iron for a quick green-up, so it colors the lawn faster than Milorganite but feeds for a shorter window and carries more burn risk. Scotts Natural Lawn Food is Scotts' organic, slow-release option and is the closest match to Milorganite; both are low-burn and feed steadily, though Milorganite's 6-4-0 adds a little phosphorus and its well-known iron content for color. For steady, low-risk feeding all three work. Choose Milorganite or Scotts Natural Lawn Food if you want organic slow-release, and Green Max only when you want a fast cosmetic green-up.

Milorganite is made from heat-dried microbes (biosolids), and like most biosolid-derived products it can contain trace levels of PFAS. The Milwaukee Metropolitan Sewerage District, which produces Milorganite, publishes testing data and reports levels that fall within applicable guidance. If trace PFAS is a concern for you, a plant-derived organic fertilizer or a synthetic slow-release product avoids biosolids entirely. For most homeowners applying a few times per year, the exposure risk is considered low.