How to Overseed a Lawn in 4 Steps

The hot temperatures of summer can take a toll on your lawn, causing thin spots or even bare patches that invite weeds to take hold. Fall is the right time to overseed your lawn if you're growing a cool season grass such as fescue or Kentucky bluegrass.

For best results when overseeding a lawn, it's vital to spread the seed at the right time, properly prepare your lawn to accept the new seed, then give the seed the best chance to germinate by watering sufficiently and regularly.

Below are steps on how to overseed your lawn as a method of reinvigorating existing turf. Note: The term "overseeding" also can refer to spreading seed over a warm season lawn to provide a green cover during the winter, which should only be done for bermudagrass lawns.

If you time your overseeding right and prepare your soil correctly, then you'll likely be rewarded with a thicker lawn that's more resistant to disease.

When is the Best Time to Overseed a Lawn?

Clint Waltz, a turfgrass extension specialist with the University of Georgia, says it's a good time to overseed when evening temperatures are in the low 60s, which is generally from mid September to mid October, depending on where you live.

How to Overseed a Lawn

1. Mow it Low

It's vital that your grass seed gets good contact with the soil so seeds can germinate. Preparing your lawn for seed starts with mowing the lawn to a height of 1 1/2 to 2 inches so the seed has a better chance of getting past the existing lawn canopy and reaching the soil.

2. Rake to Remove Thatch

Grass seeds can't germinate if they land on yard debris. Rake away any buildup of thatch from lawn clippings (from the mowing you just performed), sticks and leaf debris.

Note: This also is a good time to consider core aeration, which will further improve the lawn bed into which the seeds will be spread.

3. Spread Seed

Waltz says either a drop spreader or a rotary spreader will get the job done. The key is to get uniform coverage when spreading seed. To do so, try this: Cut the recommended amount of seed for the coverage area in half, then run the spreader over the area twice and in two different directions.

How Much Grass Seed for Overseeding: Waltz recommends spreading about 3 to 5 pounds of fescue seed per 1,000 square feet or 1 to 2 pounds of Kentucky bluegrass per 1,000 square feet.

4. Water Seed Consistently

The key to proper watering is consistency. The new seed must be kept moist, but not too wet, to encourage germination. "There is no pause button," says Waltz. "If you stop watering and let it (seed) dry out, then you'll lose the seed."

You'll want to continue to water the seed the first few weeks after spreading — about 10 to 14 days. Seed will germinate more quickly in warmer temperatures, so overseeding earlier in the suggested window of time likely will mean you'll have to water for fewer days.

Note: You don't need to put down mulch when overseeding an existing lawn. For very thin spots in your lawn, however, you could spread a light layer of pine straw as a mulch.

Also, feel free to reach out to your local extension office with any questions regarding overseeding.

Overseeding FAQs

When Should I Fertilize After Overseeding?

Waltz says you can fertilize 21-28 days after the seeds first germinate.

Note: Do not overseed if you've spread a selective herbicide within the past 60 days, says Waltz, as selective herbicides don't know the difference between crabgrass and grass seed. And don't spread an herbicide within 30 days after overseeing. "Let your mower be your weed control," says Waltz.

When to Mow After Overseeding?

Mow when the new grass seedlings grow to your intended lawn height, which could be about a month after germination. Mowing sooner could result in the seedlings being pulled out of the ground.