Overseeding is the planting of grass seed directly into existing turf, without tearing up the turf, or the soil. It's an easy way to fill in bare spots, improve the density of turf, establish improved grass varieties and enhance your lawn's color.
If a lawn looks old, or just "worn out," if it needs growing amounts of water and fertilizer to thrive, or is disease or insect prone, it's a perfect candidate for overseeding.
Many older lawns were established with common type turf grasses not suited for the needs of today's homeowner. They're often more disease and insect prone, requiring more fertilizer and water.
Overseeding newer turfgrass varieties into an older lawn can help it better withstand insects, disease, drought, shady conditions and heavy traffic. The investment in overseeding pays off by reducing the amount of water and pesticides required. Most importantly, a renovated lawn stays greener and looks thicker and healthier!
Late summer or early fall is the best time to overseed lawns. Soil and atmospheric temperatures are most favorable for optimum seed germination and growth. With adequate moisture, fertilizer and sunlight, the new seedlings will be well established before cooler fall weather sets in. Also, weed competition is less of a factor at this time, giving the grass seedlings a better environment to grow and develop.
Spring overseeding risks the chance of weather-related problems (heavy spring rains, unexpected high temperatures) and weed competition. Also, spring seeding may interfere with the application of preemergent crabgrass or broadleaf weed killers; concurrent application of seed and herbicides is generally not recommended because the herbicides may cause poor seedling establishment. It is best to delay herbicide treatment 4-6 weeks after new grass seed germinates. If you choose to overseed in the spring, be sure to follow proper seeding and treatment practices.
Midsummer overseeding faces greater chances of disease, heat and drought stress, and weed competition. Proper weed control and adequate irrigation are musts if overseeding is attempted in midsummer.
Dormant overseeding involves seeding in late fall or early winter, after soil temperatures are low enough to prevent seed germination.
Success usually requires good snow cover during the winter, to prevent wind or water erosion and ensure germination doesn't begin too early. This method is sometimes preferred over spring seeding, especially in northern areas, because you don't have to wait for soil or moisture conditions to improve before overseeding.