Scotts Turf Builder Starter Fertilizer for New Grass, 15 lb Review

Our Verdict

Ordinary lawn fertilizer is deliberately low or zero in phosphorus, because established turf rarely needs it and phosphorus running off into water is the reason many states legislated against it. A seeding is the genuine exception: a germinating seedling is building a root system from nothing, and phosphorus is what root development runs on. That is the whole argument for a separate bag at seeding time, and 24-25-4 is what it looks like — as much phosphorus as nitrogen, which you would never apply to an established lawn. Two practical points. Apply it with the seed rather than weeks later, because the window where it matters is the first few weeks of root building. And check your state: several restrict phosphorus applications, and where they do, new seeding is usually the exemption written into the rule — but the exemption is specific and worth confirming rather than assuming, which our restrictions tool covers.