When to Plant Grass Seed in Iowa

For cool-season lawns (fescue, bluegrass, ryegrass), fall is the best time to plant grass seed in Iowa, with spring the second choice: fall seedlings face less weed competition and mature before summer heat. The window opens as 2-inch soil falls back through 70°F, and germination slows sharply once soil drops below 50°F, typically around October 31. Fall seeding and fall pre-emergent are an either/or on the same turf; see pre-emergent timing in Iowa.

Spring is the second choice: the window opens when soil first holds 50°F and narrows as soil passes 65°F, typically by June 1.