April 15 through June 15 is the spring window for overseeding tall fescue lawns thinned by winter damage. Tall fescue should be seeded at a rate of 4 to 6 lbs per 1000 ft². Applying a nitrogen starter fertilizer at 1 lb N per 1000 ft² is beneficial for robust early growth. Higher tall fescue seeding rates are necessary since tall fescue has less seeds per pound compared to Kentucky bluegrass.

We are coming to the end of the April 1 to April 30 window for overseeding Kentucky bluegrass lawns. We recommend over seeding at a rate of 0.75 to 1.0 lbs per 1000 ft². If you were not able to overseed your bluegrass lawn this spring, be sure to do a good job of weed control in these areas this summer and plan to overseed in September when the heat of summer has passed. If a heavy thatch is present, de-thatching the overseeding area is beneficial for germination. Aerating a lawn (plugging) before over seeding is also beneficial. Run the aerator in multiple directions to maximize the number of holes. The hole left by each aeration core is an ideal environment for seed germination.

Information on variety selection can be found at the National Turfgrass Evaluation Program (NTEP) website (www.ntep.org). Using certified seed of improved cultivars is important. The advantage of certified seed is a known germination rate if planted properly and very little, if any weed seed contamination.