Mow cool-season grasses at 3 to 4 inches

Set your mower deck to maintain Kentucky bluegrass, tall fescue, and perennial ryegrass at 3 to 4 inches throughout spring. Start closer to 3 inches in early spring, then raise toward 4 inches as summer heat approaches.

Why It Works

Taller grass develops deeper roots, shades the soil to suppress weed germination, and retains moisture longer. Purdue Extension research shows that lawns mowed at 3+ inches require significantly less irrigation and develop fewer weed problems than those mowed at 2 inches.

Tips

• Fine fescues can be mowed even taller, at 3.5 to 4 inches.
• Measure actual cutting height by placing the mower on a flat surface and measuring from the ground to the blade.