How to Overseed a Lawn for Healthier Grass

Even with the utmost TLC, most lawns inevitably thin out and develop bare or brown patches over time. Fortunately, you don’t always have to start from scratch if yours is looking worse for wear. Overseeding can help restore your lawn to its former glory, or even spruce it up if it didn’t grow in as well as you hoped. Here’s how to overseed a lawn and get it thriving in time for backyard barbecue season. 

What Is Overseeding?

Overseeding is a relatively simple process that involves planting new grass seeds over an established lawn to fill in the bare spots and thicken the grass. You can spread seeds over an entire lawn to help boost thin, weakened grass, or you can focus on specific areas that need help (such as your dog’s favorite spot to “go”). For best results, you’ll also need to do some basic lawn and soil prep to provide ideal conditions for the new grass seeds to germinate.

Prepping to Overseed Your Lawn

A crucial step in overseeding a lawn is choosing the right type of grass that will naturally thrive in your area’s climate and soil conditions. If you haven’t done so, get your soil tested by a local soil testing service to determine the type of improvement, if any, the soil needs for grass development. This is especially important if your previous crop of grass died mysteriously or just never grew in as full and lush as it should have.

Once you have a better idea of your soil composition, you can use a soil conditioner as necessary to provide ideal conditions for your new grass seed to grow. Soil conditioners differ from fertilizers in that they have nutrients and chemicals specific to a particular type of soil. For example, lime and wood ash raise the pH of acidic soils, making them more suitable for certain grasses. Sulfur soil conditioners, on the other hand, can amend soils that are too acidic or alkaline. If the soil pH is neutral and fertile, it should be good to go. You can also improve the nutrients and condition of your turf by adding peat to clay soils and compost to sandy soils.

Once you’ve got your soil amended and your grass seed ready, here are the basic tools and supplies you’ll need to overseed:

• Grass seed

• Aeration tool

• Mechanical seed spreader (optional)

• Fertilizer spreader

• Lawnmower

• Rake

• Garden hose 

• Sprinkler

How to Overseed a Lawn

Overseeding a lawn is pretty simple, but again, prepping your soil beforehand is key. Here are the basic steps to follow.

1. Mow the Grass Short

The first step to overseeding your lawn is mowing your lawn. Mow shorter than you typically do to give grass seeds as much contact with the soil as possible. Remember that mowing more than one-third of the grass’ height at one time can weaken it, so try not to let the grass get too long before you start. Once you’re finished, bag up the grass clippings so they don't form a barrier between the seed and the soil.

2. Rake the Lawn

After mowing, rake the entire lawn to remove any dead grass, stones, sticks, and other debris. You’re aiming to remove any lingering barriers between the grass seed and the soil. This step also helps loosen the soil in preparation for seeding and germination.

3. Aerate the Soil

Next, aerate your soil to further loosen compacted soil and provide optimal conditions for nutrient absorption. If you’re covering a small lawn or area, a small manual aeration tool should suffice. For larger lawns, you might want to rent a power aerator from your local home improvement store. You can also overseed without aerating if you rake the soil beforehand.

4. Spread Your Grass Seeds

Once the soil is amended, prepped, and aerated, spread the seeds evenly wherever you want to grow more grass. It’s best to use a mechanical seed spreader for even coverage, but if you don't have one, you can also sow the seeds by hand.

5. Add Lawn Fertilizer

Next, use a fertilizer spreader to apply lawn fertilizer to the areas where you spread the seeds. You can also take this time to fertilize the entire lawn if necessary.

6. Water the Lawn

After you fertilize, give your lawn a generous amount of water, but take care not to flood the seeds. Regular and even watering is essential for seed germination. It should be evenly moist for two weeks. Aim to water twice a day; once in the morning before the hot afternoon sun hits, and once at dusk.

7. Wait Two to Four Weeks to Mow

Once you’ve spread your seeds, it’s best to avoid mowing the areas you’ve patched until the grass has grown in completely. “I recommended avoiding these areas for at least two to four weeks,” says Tara Dudley, owner of Plant Life Designs.

Tips for Overseeding

Overseeding is pretty straightforward, but there are a few key strategies to help your new seeds germinate and grow into a healthy green lawn. Here are some important tips to keep your grass healthy:

• Avoid overseeding on days that are excessively windy or rainy.

• Try to avoid walking on the areas you’ve overseeded for at least two weeks.

• Keep your soil moist throughout the growing season.

• Don’t overdo the fertilizer.

• Don’t let your lawn get too long between mowings.

• Overseed once every one to three years, or as needed.

• Time your overseeding according to the type of grass you’re planting.

DIY vs. Hire a Pro

If you’re still having trouble achieving the lush, healthy lawn you’ve always wanted, or if you’re just having trouble finding time for upkeep, consider bringing in a pro for extra help. A local lawn seeding professional can customize your treatment plan to create ideal conditions for your new lawn to grow. 

You will pay a little more, though, to hire a pro to do the work for you. In general, seeding a lawn costs $250 and $350 in labor fees alone. But you may find it well worth the cost to save yourself the time and elbow grease required to help your lawn flourish.

Amber Guetebier contributed to this piece.