How, When and Why to Overseed Your Lawn

Overseeding your tired grass can give it a much-needed facelift. Think of it as a software update for your lawn.

Summer can take a lot out of your lawn. Hot, dry conditions and heavy shade cause the most grass damage. Outbreaks of disease and insect activity can make matters worse. And if you have kids or pets, your lawn may be worn to shreds, exposing the soil beneath. Not good!

General yard maintenance helps. But like other home assets, such as your exterior walls and kitchen appliances, the amount of TLC you give your lawn can go a long way. Fall overseeding after a summer’s worth of stress and abuse will pay dividends, keeping your lawn looking and performing its best once the snow melts next spring.

Your lawn can’t dodge general wear and tear caused by Mother Nature. And the way you and your family use your lawn can add to your maintenance woes. By season’s end, your grass is tired and showing signs of stress.

What is Overseeding?

Overseeding is another term for reseeding. Lawns need to be restored occasionally and choosing the right grass seedĀ for the job is critical. Overseeding is a great way to repair damage and thicken thin areas before winter sets in.

Many older lawns can also benefit from overseeding. Introducing new genetics to your lawn will result in a better appearance and performance. Old lawns contain obsolete seed varieties. Newer grass seed varieties are darker green and have better disease resistance and overall turf quality. Updating your lawn with improved seed genetics can give your lawn a much-needed facelift.

When is the Best Time to Overseed?

Hands down, early fall is the best time to overseed your lawn. The absolute sweet spot for most northern regions of the U.S. is August 15 to September 15. That’s when daytime temperatures are still warm enough to encourage growth and nights get cooler, giving new seedlings a break from the heat. Lawn grasses like that. Soil temperatures are ideal, too, resulting in quicker seed germination.

But don’t let missing that perfect seeding window stop you. Depending on where you live, overseeding can be done all the way through September and into early October. Weed competition is virtually nonexistent and predictable rains fall softly with few “gully washers” that could wipe out your efforts in 15 minutes. All these factors create the perfect late summer/early fall window for overseeding your lawn.

How to Overseed a Lawn

With the help of a few basic tools, a nearby rental store and a free weekend, you can restore your lawn’s original health and beauty. Fall is a great time for other lawn care projects, too. Aerating and fertilizing are perfect companions to overseeding, as long as they happen a week or two before you overseed.

Start by mowing your lawn and raking up any leaves or clippings left behind. Then aerate your lawn and, if you wish, fertilize it. In the next week or so, go ahead and spread your grass seed. Then, make sure your sprinklers are working to keep the yard well-watered.

How to Maintain Your Lawn After Overseeding

Grass seed takes seven to 21 days to germinate.

  • You’ll need to keep your lawn moist during this time to trigger germination. If you have an irrigation system, this is easy to do. Otherwise, you’ll need to set out a sprinkler or water smaller areas by hand.
  • Once you see seed popping up, don’t stop watering. These little seedlings need to be nurtured during their first eight weeks of existence. Without a mature root system they can dry out quickly and die.
  • Applying a starter fertilizer at the time of overseeding is not necessary. If you normally fertilizer your lawn, there are enough nutrients in the soil to get the new seed growing. Applying fertilizer to your lawn after overseeding can create unnecessary competition from existing grass, making it difficult for new seedlings to get established.

And fall is a great time to control broadleaf weeds, but be careful when combining killing weeds with overseeding. New grass seedlings can be damaged by herbicides if you spray weeds immediately before or after seeding. Always read and follow the herbicide label. A step-by-step approach to fall lawn care will guide you through the process, allowing your lawn to take just about anything Mother Nature or your kids will throw at it.

Joe Churchill
Joe Churchill is a Senior Turf Specialist for Reinders, Inc. in Plymouth, MN with a passion to promote realistic and environmentally-sound turfgrass maintenance practices through responsible use of water, fertilizers, pesticides and other inputs. Joe's client base includes professional turf managers serving the lawn care, sports turf and golf course industries. His lawn is the envy of the neighborhood and, in his free time, he enjoys kicking back on the Northshore of Lake Superior.