How to Overseed a Lawn

Rather than replacing your entire lawn, overseed those brown patches and bald spots. It’s an easy DIY project, as long as you have the right tools and a little patience. Here you’ll find precise tips on just how to overseed your lawn, the benefits of overseeding, and the best time of year to get started.

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What is Overseeding?

Overseeding is simply spreading fresh grass seed directly into the existing lawn without tearing up the turf or the soil. It’s an excellent way to make your lawn thicker and greener. By mixing types of grass seed, you can even prolong the life of your lawn and enjoy it year-round. 

Overseeding Tools You’ll Need

Let’s face it: We all end up making twice as many trips to the home store as anticipated, looking for that one last item we forgot. Start here, gather your materials, and finish your shopping in one day.

  • Lawn rake
  • Lawn mower
  • Fertilizer spreader, broadcast spreader or drop spreader
  • Enriched topsoil, if not included in your seed mixture
  • Grass seed 
  • Dethatcher and aerator

How to Overseed a Lawn in 9 Easy Steps

Step 1: Decide When to Overseed

The first step is deciding when to spread the seeds. This is typically done in late summer or early fall, depending on if you have cool-season or warm-season grass in your yard.

Step 2: Remove Thatch and Aerate

Like any plant, grass seeds need to find their way to the soil to germinate. But thatch can get in the way. Thatch is the organic matter like grass and leaves that accumulates atop the soil. If you can’t see soil between your existing grass, remove the thatch with a dethatcher.

After dethatching, you’ll need to aerate. Spike aeration pokes holes in the solid while core aeration pokes holes and removes plugs of soil, giving your grass seed the space it needs to germinate. 

Pro Tip: It’s unlikely you have a dethatcher or aerator hanging out in your shed. The local home supply store should have a selection to choose from. Look for rental opportunities while you pick up the fertilizer and grass seed. 

Step 3: Mow the Grass

In order to help the seeds reach the soil, cut the grass to about one inch. This is likely shorter than you normally mow, so you’ll need to drop the blade.

It’s also important to bag the trimmings and remove them. Again, this is all about increasing the likelihood of the new seeds making soil contact and germinating successfully. If you don’t have a way to bag the clippings, the next step will help.

Step 4: Rake the Lawn

Rake up all of the leaves, twigs, clippings, and other debris on your lawn. It’s best if you add a little muscle to the raking process, allowing the rake tines to loosen up the soil as well.

Step 5: Add Nutritious Topsoil 

Use a fertilizer spreader to add a layer of enriched topsoil on top of your grass. This top layer of soil is filled with organic matter and microorganisms necessary for life to develop. Topsoil makes sure the seeds have access to water, nutrients, and space to germinate. 

This layer should be about ¼-inch thick. Some grass seed mixtures include topsoil, so you won’t need to add additional topsoil and can jump to the next step.

Step 6: Spread the Grass Seed

Finally, it’s time for seeding! Like most aspects of lawn care, it’s essential to know just what type of grass you’re working with. Either use the same seed as your existing lawn or a variety that compliments it. For example, overseed a Zoysiagrass lawn with Zoysia seed, or a cool-season ryegrass to add color in the winter.

Read the bag’s instructions for how much seed to apply per square foot, and fill your drop spreader or broadcast spreader accordingly. Walk the spreader across your lawn in the same direction you mow, depositing the seed in rows.

Step 7: Apply Fertilizer 

To jumpstart growth and ensure the new seeds have what they need, use a fertilizer spreader to add a starter fertilizer appropriate for your lawn. Starter mixes are specially designed for new growth and should be applied wherever you spread the seeds. 

If your grass seed mixture already contains fertilizer, you can skip this step.

Pro Tip: Stay away from “weed and feed” mixtures as these herbicides can damage to new growth.

Step 8: Give the Grass a Drink

New plants always require water, and your new grass seed is no different. As soon as you finish spreading seed and fertilizer, give your lawn a good, healthy drink.

You’ll then water your lawn lightly two to three times each day, ensuring the soil stays moist. This should continue until the new grass is as tall to established grass. Always water in the morning or after sundown so as to prevent evaporation. 

You should also look for signs of overwatering, such as puddles or squishy soil. If you notice this, stop watering right away and wait until conditions return to normal.

Step 9: Be Patient

Along with consistent watering, you should also stay off your grass until it has had a chance to develop. Limit foot and paw traffic until the grass has at least 1- to 2-inches of growth, and don’t pull out the mower until the new grass is similar in height to the established grass. Giving your new lawn a chance to take hold is the final step in overseeding.

Why Overseed the Lawn?

When you overseed your lawn, you give it the ability to resist disease, drought conditions, and heavy foot traffic. A thicker lawn is also more resistant to lawn damaging insects. It also requires less fertilizer and maintenance.

FAQs About How to Overseed a Lawn

1. Why mow the lawn before overseeding?

A shorter lawn gives the seeds a better chance of reaching the soil. It’s also important to loosen the top layer of soil and remove any dead grass or thatch, so the grass seed can easily take root and germinate.

2. How do I prevent the birds from eating the grass seed?

Add a layer of topsoil over the seeded areas. This prevents the birds and other wildlife from getting to the seed. If you notice birds or rabbits near the area, get a roll of burlap and place strips of it over the seeded area. Anchor the strips with tent stakes.

3. How long after overseeding will I see grass start to grow?

It takes two to three weeks for germination to begin. With proper watering, you should start to see the grass spout within four weeks. It will take about eight weeks to see a fully established lawn.

4. How often should I overseed my lawn? 

Annually. Most lawn care professionals recommend overseeding each year to keep your lawn coming back thicker and greener every spring. If you only see bald spots and thinning every once in a while, you can probably overseed once every two or three years.

5. Do I need to apply fertilizer when overseeding my lawn?

Only if you didn’t fertilize in spring. Adding more fertilizer isn’t necessary, and may actually hinder your new grass seed from growing. Fertilizing just before or after reseeding will force the germinating seeds to compete with the existing grass and weeds. It’s best to wait until the following spring to fertilize.

Overseeding is easy enough to do as a DIY project, but if you’d rather not spend your time checking soil temperatures, dethatching, and aerating, we can help you find a lawn care professional near you.

Main Photo Credit: Brenda Ryan | LawnStarter

About Wikilawn

Wikilawn’s mission is to provide the best resources and information to help you enjoy your outdoor spaces the way you want. Whether you are a DIY, lawn-loving, gardening guru, or someone who wants help in picking a local lawn care professional, we can smooth your path to a beautiful backyard!

About Wikilawn

Wikilawn’s mission is to provide the best resources and information to help you enjoy your outdoor spaces the way you want. Whether you are a DIY, lawn-loving, gardening guru, or someone who wants help in picking a local lawn care professional, we can smooth your path to a beautiful backyard!