When to Reseed Lawns
Is your lawn in desperate need of a do-over? Too many weeds or bare spots and not enough healthy grass? These might be signs that you should reseed your lawn.
Reseeding at the right time allows your grass to grow healthy and strong, instead of struggling against the blaring summer sun, or cold winter days. Once you establish the best time to reseed for your grass type, you can begin growing a new lawn full of healthier, greener grass.
When to Reseed vs. Overseed
Reseeding is often confused with overseeding, which is the process of applying seed to your existing lawn to thicken up thinning areas in your yard. Reseeding, in comparison, involves first, killing the existing grass and weeds, then starting over with new grass seed.
While overseeding is a great way to thicken an existing lawn, Jonathan Green recommends reseeding a lawn when more than ½ of your yard is full of weeds or bare spots.
Starting from scratch may seem extreme, however, reseeding is sometimes your only option if you don’t want to fight weeds for years to come. In order to have uniform, green grass, you have to hit the reset button and reseed your lawn.
The Best Time to Reseed Lawns
The best time to reseed is unique to your type of grass and climate conditions. However, for cool-season lawns, the cool air temperatures and warm soil in early fall ensure proper seed germination. It’s important to time your reseeding project just right in order to achieve a lush, green lawn.
Cool Season Lawns
Cool-season grasses—like tall fescue, Kentucky bluegrass, and perennial ryegrass—thrive when planted during the cooler parts of the year. The best month to reseed a lawn with cool-season seed is typically early fall, between mid-August and early October, or at least 45 days before the first expected frost.
If you’re wondering when to reseed in fall, early in the season is ideal. This allows time to kill off the existing lawn and wait a minimum of two weeks after applying herbicide before seeding—timing that’s critical for strong germination and root development.
Before reseeding, apply a non-selective herbicide containing glyphosate to clear out the old lawn. Glyphosate is most effective during the active growing periods of cool-season grasses—spring and fall—making those seasons optimal for both killing existing growth and reseeding.
Keep in mind that glyphosate is a broad-spectrum herbicide, meaning it can damage any plant it touches. Always follow label instructions carefully, and ensure the recommended waiting period (usually two weeks) has passed before applying new seed. This ensures residual chemicals don’t interfere with germination.te.
Apply herbicide in the morning when temperatures range between 65–85°F, and avoid windy conditions to prevent drift to surrounding plants.
If you miss the early fall window, your next best month to reseed a lawn falls in early spring—between mid-March and early May—before temperatures climb too high. Avoid reseeding during periods of extreme heat or cold, as young grass seedlings require soil temperatures of at least 60°F to successfully germinate.
If you reseed during the summer, the heat causes stress to grass seedlings and makes it difficult for them to grow. Winter presents even more challenges, as there is less rainfall and both air and soil temperatures are too cold for seed to germinate and survive.
Warm Season Lawns
Warm-season grasses, such as St. Augustine, bermudagrass, and zoysia, have a higher tolerance for warmer air temperatures and require more sunlight than cool-season grasses.
You should reseed lawns with warm-season varieties when soil temperatures are above 65°F.
Why Early Fall is the Best Time to Reseed Lawns
Not only does early fall have the best weather conditions, and soil temperatures, but it also allows you enough time to kill your existing grass and reseed your lawn before the first frost arrives. Typically in early fall, the air temperature is cool enough that the seedlings won’t dry out and warm enough that conditions are right for seedlings to germinate. Reseeding in fall also gives the grass time to grow and establish a deep root system before the hot summer months.
The Bottom Line
Without a doubt, early fall is the best time to reseed a cool-season grass lawn. If you reseed in temperatures that are too hot or too cold, the seedlings won’t germinate, and all of your hard work will go to waste! Knowing the right time to reseed will ensure you only need to do this process once.
The sooner you reseed your lawn, the sooner you can have the lawn of your dreams!
Once you make the decision to reseed and give your lawn the best treatment possible, the end result will be a revitalized lawn full of stronger, healthier grass.
For more tips, articles, and videos on planting grass seed, visit our Lawn Care page!