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Overseeding Lawns

submitted by Sarah Browning, UNL Extension Educator

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Last summer was hard on lawns, and many have sections where grass has died. These areas are pretty easy to spot now. Look for patches that did not green up last fall, and now have bleached, light tan leaf blades lying flat on the ground. These areas will need to be reseeded to re-establish healthy grass, and prevent weed invasion this spring.

Purchasing Seed

Kentucky bluegrass and turf-type tall fescue are still the best cool-season grass choices for home lawns. Last summer’s heat and drought were exceptional, and it’s unrealistic to expect unirrigated turfgrass to survive those conditions without damage. In some cases, even irrigated lawns had damage in areas with compacted soil or on slopes. So there isn’t a “better grass” choice. However, make sure when buying seed to purchase a high quality, certified seed blend. Remember- scrimping on the quality of the seed will soon be evident in the quality of turf.

Seed that is certified by the Nebraska Crop Improvement Association is usually identified with a blue tag on the seed bag. A good grass blend should include 3-4 different cultivars of the grass you choose- Kentucky bluegrass or turf-type tall fescue. Bluegrass and fescue can also be blended together. Check the seed label and avoid seed blends that include coarse textured, pasture grasses like K-31 tall fescue or annual grasses like annual bluegrass or annual ryegrass.

Seeding

Consider overseeding now, or as soon as the snow melts and soil is workable, by making a “dormant” application. Normally spring overseeding of Kentucky bluegrass is done from April 1st to April 30th; tall fescue- between April 15th and June 15th. However, putting seed down now allows it to begin growing as soon as soil temperatures warm, and takes full advantage of spring rain. As long as soil is not frozen or excessively wet, now is a great time to prepare the soil and spread the seed.

The amount, or rate, of seed applied when overseeding is less than the full seeding rate for bare ground. The full seeding rate for Kentucky bluegrass is 3-4 lbs. per 1,000 sq.ft., and tall fescue 8-10 lbs. per 1,000 sq.ft. When overseeding into an existing stand, the rate can be reduced by up to 50%, meaning that bluegrass should be applied at 1-2 lbs. per 1,000 sq.ft. and tall fescue at 4-6 lbs. per 1,000 sq.ft. When working with small amounts of seed, mix sawdust, dry sand, or any other suitable material with the seed to aid in obtaining uniform coverage.

Prepare the Area

Before spreading the seed, prepare the soil to create a good seedbed. Small areas can be prepared by hand raking to remove excess dead top growth and loosen the soil surface. Larger areas should be heavily aerated or power raked. Aerating opens up the soil and provides a good surface for seed germination. Seeds that fall into the aeration holes will germinate and grow well; there is no need to topdress or fill in the holes before seeding. Power raking should be used only if a thatch layer in excess of 1/2" is present.

Follow Up Care

Hopefully, eastern Nebraska will receive some spring rain in late March and early April. But if we don’t, then you’ll need to start irrigating the seeded area, starting around mid-April, until germination has occurred. After germination, gradually decrease the amount of water applied. Kentucky bluegrass should receive 1" of water during spring and fall, and 1.5" of water in mid-summer. Apply water deeply and infrequently to encourage deep rooting.

Applying a pre-emergent herbicide for weed control is especially important with spring seedings since weed pressure is so much greater early in the year. The only pre-emergent herbicide that can be used with new seedings is Siduron, commonly sold as Tupersan. This herbicide will provide good control of annual grassy weeds like crabgrass and foxtail, yet still allow the grass seed to germinate. For new seedings, use the lower recommended rate and repeat the application one month later.



This resource was added March 2013 and appeared in the Lincoln Journal Star Newspaper Sunday edition. For information on reproducing this article or using any photographs or graphics, read the Terms of Use statement

 

University of Nebraska-Lincoln Extension in Lancaster County is your on-line yard and garden educational resource. The information on this Web site is valid for residents of southeastern Nebraska. It may or may not apply in your area. If you live outside southeastern Nebraska, visit your local Extension office


Contact Information University of Nebraska-Lincoln in Lancaster County
Web site: lancaster.unl.edu
444 Cherrycreek Road, Suite A, Lincoln, NE 68528 | 402-441-7180