Kentucky bluegrass is a hardy plant and handles winter and summer extremes well. It grows best in moist, well-drained soil in full sun. Kentucky bluegrass seed is sold as a blend of several varieties of Kentucky bluegrass. If you are planning to overseed, use a blend of at least three varieties.
Mow your lawn and rake it with an iron rake. Aerate your lawn thoroughly with a spike aerator. then overseed with bluegrass seed by broadcasting. Aerate the lawn again and roll it to pack the soil around the seeds. Continue your regular watering, mowing and fertilizing. Figure 1 to 3 pounds of seed per thousand square feet.
Early Autumn between August and September is the best time to overseed your lawn. You can also overseed in the spring before May. Some overseed in both fall and spring. You can also overseed in late autumn along with a winter cover like ryegrass. Fall planting gives your grass a head start for spring.