How to overseed your lawn in fall and when to do it

A pair of cupped hands spreading grass seeds in a lawn
(Image credit: Shutterstock)

It’s been a difficult summer for lawn care to say the least. The endless heat waves have left many of us questioning how much you should water your lawn, and if you couldn’t keep on top of demand, the result is dead grass everywhere and crabgrass galore. Many lawns have now been left with ugly bald patches of soil scattered as far as the eye can see. 

While you might think learning how to plant grass seed is the answer, overseeding may be the better method if you’re dealing with patches of exposed soil. The fall provides ideal conditions for overseeding, however with winter approaching, your window is quickly closing and you need to act fast if you want to get those patches covered and growing in time to survive. Here’s what you need to know about overseeding your lawn in the fall. 

If your lawn is covered in thatch, be sure to learn how to dethatch a lawn before you begin overseeding. And find out whether grass seed vs sod is better for your lawn.

When should you overseed your lawn in the fall? 

Overseeding is best done in the early fall, between mid August and early October — so there’s still time to repair your yard. The main event you want to avoid is the first frost as any seedlings will perish.

The type of grass seed you’re sewing can make a difference to the best soil conditions as well; cool-season grass, such as Kentucky bluegrass, prefers soil temperatures below 65°F, while warm-season grass, like Bermuda grass, prefers temperatures of at least 65°F.

You can use a basic soil thermometer to check the conditions, such as the Urban Worm Soil Thermometer ($10.29, Amazon). Because of this, you are better-off overseeding warm-season grasses earlier in the year, from late spring to early summer.

A hand scattering grass seeds into the soil

(Image credit: Shutterstock)

While you might think what remains of the heat of summer will make for ideal growing conditions, don’t overseed at this time. Grass seeds are fragile and actually prefer moist conditions and lower temperatures to germinate. So, if you’re still facing the final stages of a drought, hold off on overseeding. Because of the moisture preference, overseeding is also best done a day or two after rainfall, but bear in mind you want the soil moist, not saturated.  

It’s also good practice to overseed your lawn as soon as it’s been aerated. The better air circulation and access to nutrients in the soil gives grass seeds an improved chance of growth. Plus, if the seeds land in the puncture holes, they have a better chance of retaining moisture. See our guide on how to aerate a lawn for full instructions on this. 

dandelions in grass

(Image credit: Shutterstock)

There should be fewer weeds at this time of year (another reason why overseeding is ideal in the fall), but you’ll want to remove any that remain before overseeding. The roots of weeds are strong and dominating — these will hog the nutrients in the soil, which will stunt the growth of your grass seedlings.

Check out our guides on how to get rid of dandelions and how to get rid of crabgrass for specific instructions. Be careful where any seed heads have developed on weeds prior to removal; if these disperse on removal you could have more weeds crop up next season. We recommend Grandpa’s Weeder for everyday weeding ($39.99, Amazon). Take care if you plan to use any herbicides as these can often kill grass seeds; always read the label to be sure.  

How to overseed a lawn 

1. Choose the right grass seed — Before anything else, make sure you’re planting the correct type of grass seed to match the rest of your lawn. Cool-season grasses are often found in the north, while warm-season grass frequents the south. If in doubt, consult an expert at your local home department store. 

2. Mow your lawn — When it comes to overseeding, the first step is to mow your lawn to a low height. Cut it down to about 1.5-2 inches in length. 

3. Rake the dead grass — Take a rake to your lawn afterwards to remove any dead grass. You might think this is making things look worse, but this clears the area for the seeds to reach the soil.   

4. Check your soil — Check the conditions of your soil using a soil test and add amendments as necessary to improve it's habitability. We recommend the Luster Leaf 1602 Soil Test Kit ($13.07, Amazon).

A core aerator being used to aerate a lawn

(Image credit: Shutterstock)

5. Aerate the lawn — Now you want to aerate the lawn to give the soil a new lease of life. This will loosen up and rotate the soil, allowing for better air circulation and nutrients, so it’s an important step. 

6. Overseed — Apply the grass seed by hand or using a spreader to areas where you want fresh growth. Make sure you follow the dosage instructions according to the label. If you aerated your lawn, aim to spread the seeds via the holes left behind. We recommend the Scotts Turf Builder EdgeGuard Mini Broadcast Spreader ($44.90, Amazon). 

7. Apply fertilizer — Now your grass seeds are in place, you will need to give them all the help they can get and that includes fertilizer. Apply a fertilizer designed to aid the growth of young grass, such as Scotts Turf Builder Starter Food for New Grass ($22.99, Amazon). 

Young grass growing out of the soil

(Image credit: Shutterstock)

8. Water regularly — When grass is young, it is fragile, and it will require constant moisture to aid its growth. The soil will need to be watered 1-2 times a day to start, although keep in mind you want conditions moist, not saturated. It can take from 1-3 weeks for grass seeds to germinate, so be patient and continue to tend to them. Once the grass reaches 1-2 inches in height, you can scale back how often you water it.  

How often should you overseed the lawn?

The answer to this largely depends on the environmental conditions. If harsh weather, such as repeated droughts, takes its toll, grass could need overseeding annually to keep up with the damage. However, in most cases overseeding will only be necessary every couple of years. Essentially, if you notice your grass is looking thin and worse for wear, that’s a sign that it’s time to overseed.   

For more lawn tips, tricks, and how-tos, check out our guides on how to plant grass seed, how to make your grass greener, how to stripe your lawn, how to fix a waterlogged lawn, how often should you fertilize your lawn and when to do it, how to lay sod, 7 common lawn care mistakes you're probably making right now, this is when you should stop mowing your lawn for the winter and read about the 7 ways to revive dead grass. If it's Fall and you're lawn is full of leaves — here are 5 ways to use fallen leaves in your garden.

Katie Mortram
Homes Editor

Katie looks after everything homes-related, from kitchen appliances to gardening tools. She also covers smart home products too, so is the best point of contact for any household advice! She has tested and reviewed appliances for over 6 years, so she knows what to look for when finding the best. Her favorite thing to test has to be air purifiers, as the information provided and the difference between performances is extensive.