Perennial Ryegrass: Mowing Height, Seed Rate and Lawn Care

Mow perennial ryegrass at 2 to 3 inches, raising it to 3 inches in summer to shade the soil. Blade sharpness matters more with ryegrass than with most grasses. Its leaves are tough and fibrous, so a dull blade tears them and leaves white or tan frayed tips across the whole lawn a day or two later. Sharpen or swap the blade at least once or twice a season, and more often if the tips look ragged; the steps are in lawn mower maintenance.

The Honda HRX-BE 21 in. Battery Self-Propelled Mower uses a twin-blade deck and adjusts from 0.75 to 4 inches, and the EGO POWER+ LM2135SP 21 in. Select Cut Self-Propelled Mower Kit ships with three sets of lower blades and a 1 to 4 inch range. Stick to the one-third rule: mow a 2.5 inch lawn before it reaches about 3.75 inches.

At 5 to 7 pounds per 1,000 square feet, a 5,000 square foot new lawn needs 25 to 35 pounds and overseeding needs 15 to 20 pounds. An acre from bare soil takes about 261 pounds at the 6 pound midpoint. The GreenView Pure Grass Seed Perennial Ryegrass Blend, 20 lb label covers 5,000 square feet new from 20 pounds, a lighter 4 pounds per 1,000 square feet; heavier seeding within the extension range gives faster cover on bare soil. If you want ryegrass as one part of a darker cool-season lawn, the Jonathan Green Black Beauty Ultra Grass Seed, 7 lb blends it with tall fescue and Kentucky bluegrass.

Ryegrass seedlings are aggressive. In a mix, too much ryegrass by weight crowds out slower bluegrass, so most northern mixes keep it a minor share. Spread seed in two perpendicular passes; see how to overseed a lawn.

Late summer to early fall, when soil is 50 to 65 F, is the best window, and because ryegrass is so quick it is also the most reliable cool-season grass for spring patching once soil passes 50 F. Seed spring patches early enough that the grass has several weeks of cool weather before summer. Most crabgrass pre-emergents stop ryegrass seed too, so skip them where you are spring seeding unless the label says the product is safe for new seedings.

In the South, ryegrass overseeding of dormant bermudagrass happens in fall as soil cools; the details, including the bermudagrass transition in spring, are on the annual ryegrass page.

It is the most wear-tolerant cool-season lawn grass, which is why athletic fields overseed with it. It cannot repair itself, though, so play areas, dog runs and paths need a light overseeding at 3 to 4 pounds per 1,000 square feet every fall and sometimes again in spring. Loosen compacted soil first: the Agri-Fab 48 in Tow-Behind Plug Aerator pulls plugs up to 3 inches deep across 48 inches behind a tractor. Keep new seed moist with an adjustable sprinkler such as the Melnor XT Oscillating Sprinkler, 4,500 sq ft, which covers a 4,500 square foot rectangle or a smaller seeded patch.