How to Overseed a Lawn

How to Overseed a Lawn the Right Way

Despite popular belief, a thick, lush, green lawn does not just happen overnight without any effort. While it may be common knowledge to landscaping and gardening professionals, the secret to a thick, beautiful lawn is unknown to many. In this article I’ll explain how to overseed a lawn to improve your grass.

Growing a beautiful lawn takes more than just time and luck; it takes proper overseeding. Now you may be thinking, “what is overseeding?

Trust and Accuracy Information

This article was last updated on by Lawn Chick Owner Sarah Jameson
Article content reviewed for accuracy by Certified Horticulturist Nicole Forsyth, M.S.

What is Overseeding?

Overseeding is the act of planting grass seed directly into an existing lawn or turf without turning over the lawn or turf.

This means that no holes are being punched in the lawn and your existing lawn turf is not being torn up as part of your seeding project.

Some people prefer to aerate and overseed their lawn at the same time, but mechanical aeration or using a slice-seeder to improve seed-to-soil contact is not required to effectively overseed your existing lawn.

Now that you know what overseeding is, you may be thinking, “why is it important?

Why Overseed Your Lawn?

How and Why You Should Overseed a Lawn

Overseeding is important because it can act as an easy way to fill in bare spots in your lawn.

These spots may have been left by a variety of factors, such as weather, stray toys, neighborhood dogs, etc.

Overseeding your lawn can also help to improve the density of your lawn grasses. This can prevent weeds from taking root.

It can also enhance the color and uniformity of your lawn’s appearance.

Overall, overseeding a lawn is important in maintaining a healthy lawn. In my view it’s one of the most important lawn care practices homeowners can undertake to transform the appearance of their yard.

While overseeding is much easier than tearing out your lawn and starting from scratch, it is also super easy to overseed incorrectly.

Making mistakes can damage your lawn instead of helping it. Also, grass seed is expensive. You want to make sure you’re getting the most value from every seed you spread on your lawn.

Here are my best tips on how to overseed a lawn the right way.

My Favorite Grass Seed

Patented, Proven, Performance Grass Seed.

I use and recommend Jonathan Green’s elite grass seed product line. It’s the best choice for most northern and transitional zone lawns, and it’s what I overseed my lawn with every year.

TIP: Compare manufacturer’s price to Ace Hardware and Amazon pricing.

Think About What You Want to Accomplish with Overseeding

Most people, when they think about overseeding, think about doing it to help out a lawn that has thinned.

However, it can be best to think about overseeding as a preventative measure. Overseeding can help prevent weeds from taking over your lawn.

No matter why you’re overseeding your lawn, once you have your goals straight, then you can think about how to overseed properly.

With Overseeding, Timing is Everything

Overseeding, like most things in lawn care, requires proper timing. If you do it at the wrong time of year, you’ll be wasting your time and money and you’ll be disappointed with the results.

Here are some great general timing considerations for different types of grass:

  • Cool-season grasses – the best time to overseed this type of grass is in the late summer or early fall. Overseeding for this type of grass happens the most successfully when the grass is already thriving and growing vigorously. The warm soil from the summer months will encourage germination, and the cool air in the fall will help to stimulate growth. 
  • Warm-season grasses – The best time to overseed this type of grass is in late fall or early winter. For tougher grasses, it is recommended to overseed at least 45 days before the first frost, or if you live in warmer climates, 45 days before it hits the coldest time of the year. 

Related – Use this grass zone map to learn about your local growing zone.

Many people want to overseed in the spring, because this is the time of year when their lawn is top-of-mind.

While you can have success overseeding in the springtime, I don’t recommend it, because the hot summer months inevitably put stress on your young grasses, and you won’t have the same return on your investment when overseeding in the spring.

For Overseeding, Preparation is Key

Lawn Overseeding Guide - Preparation

When you begin to overseed your lawn, you have to prepare the area. To prepare your lawn for overseeding:

  • Mow your lawn shorter than you normally would.
  • Remove all of the clippings (bag them, then rake whatever the mower misses).
  • Loosen the turf with a rake.

Mow your lawn shorter than usual to improve the percentage of seed that contacts the soil.

You’ll also want to delay mowing your new grass after overseeding. Mowing your lawn close will buy you some extra time before you have to mow. Mowing too early can rip your new grass out because it won’t have strong enough roots.

For normal mowing I recommend mowing 1/3 of the grass length. When overseeding, get closer to 2/3 of the grass length cut and raked.

After mowing and bagging your clippings, rake over the area to remove all excess clippings and debris and to begin to turn over the soil, so it is ready to receive the new seed.

Rake Your Turf After Mowing to Improve Soil Contact When Overseeding Your Lawn

Raking is a good way to loosen the soil in your lawn so your grass seed has good contact. Without good soil contact, your seed won’t germinate and grow.

I go over my lawn with an iron rake (like the one pictured) to loosen the turf, but you can core aerate your lawn or use a dethatcher to expose the soil and get good seed-to-soil contact as well.

The Dethatcher I Use & Recommend

For lawns up to a half acre there’s one clear choice when it comes to dethatching tools. I recommend The Greenworks 27022 10AMP Electric Dethatcher.

It works really well and will pay for itself after a few uses when compared to renting a power rake.

Know Your Grasses

Be sure that you choose a seed that is going to work for your climate. Also choose one that will work with your existing grasses.

Likewise, you will want to choose top quality seed that you can depend on to keep growing all year long.

It is also important to consider the amount of sunlight that your lawn will be getting. Do not choose a grass seed that requires a lot of sunlight to grow if your area is heavily shaded.

If possible, use grass seed that spreads via Rhizomes. These grasses send shoots and roots out horizontally. This will naturally fill in bare spots on its own for years, giving you a very thick, dense lawn.

It’s Time to Spread the Seed.

Once you have prepared the area by mowing the grass, raking, and choosing your seed, it is time to spread the seed. Be sure to check the seed label to know the rate of overseeding.

Using a lawn spreader, available at most home improvement and gardening stores, spread the seed around your lawn.

Spreading the seed is a pretty self-explanatory process; however, it is important to do it when the air is calm. Do NOT try to spread the seed on a windy day, as you will ultimately miss your lawn and waste your seed. Likewise, working when the air is calm ensures even distribution of the seed.

The Spreader I Use & Recommend

I’ve owned and used a number of different broadcast spreaders, and if you want the best one available, I recommend The Andersons Yard Star spreader. It is American made, can hold 50 pounds of material, rolls smoothly and easily, and is the most accurate spreader I’ve ever used.

Take Care of Your New Seed

Fertilizing your new seed is essential for its growth. Fertilizer delivers essential nutrients that help it to germinate and grow into the healthy lawn that you want.

All-natural fertilizer is the best option for fertilizing your new seed, as phosphorous supports rapid root growth; however, there are restrictions on certain types of fertilizer, so be sure to check restrictions in your area.

My go-to method is to broadcast a thin (1/4″ to 1/2″) layer of compost over my lawn after spreading the new seed.

Top Dress Your Overseeded Lawn with Compost for Best Results
TIP: For lawn overseeding success top-dress your lawn with a thin layer of compost.

Not only will this ensure good contact with your new lawn seed, it feeds your established grasses. It’s pretty cheap to order a delivery and spread it with a wheelbarrow and shovel.

Water It (the right way)

Water is one thing that new seeds need a lot of. Be sure to keep your soil constantly moist with light waterings about twice a day for the first week. After the first week, water your lawn more heavily for a week.

After the first two weeks, water as needed to prevent wilting and to promote a healthy lawn. With this watering schedule, you will be promoting healthy roots, which will lead to healthy grass and a beautiful lawn.

Regular Maintenance is Critical

After the first two or three weeks, you can return to normal lawn maintenance. You new seed should be sprouted and rooted, and your lawn should be looking healthier than ever.

Overseeding a Lawn

How to Overseed a Lawn: Common Mistakes to Avoid

Now, at this point you may be thinking, “overseeding seems pretty easy, how can anyone mess it up?” Here are the most common mistakes to avoid when looking to overseed your lawn:

  • Using the wrong type of seed. Like we mentioned before, you have to choose a seed that is compatible with your lawn, climate, and sun patterns. Likewise, choosing a cheaper seed means you are getting seeds that are older, past their planting prime, and likely filled with more weeds.
  • Ignoring the recommended seeding rates. Seeding rates are not just a recommendation. By using the proper amount of seed for your project, you are increasing your chance of success. Keep in mind, growing a lawn from scratch or repairing a completely dead spot will take twice as much seed as trying to fill in a thinning area. That being said, using too much seed can harm your grass by causing excess competition for the necessary resources for proper growth.
  • Ignoring proper timing. While it can be tempting to overseed your grass the moment it starts to thin, proper overseeding only occurs at the right time of the year with the right type of grass. We recommend following the above season recommendations for both warm and cold seasoned grasses.
  • Using weed treatments directly after overseeding. When it can be tempting to use weed treatments to keep your new lawn healthy, it is important to avoid them. These products cannot distinguish between your brand new baby grass and the brand new baby weeds. It is best to just use an all-natural fertilizer.

Overseeding can seem like a daunting process. But, once you know how to do it and the things to avoid, overseeding can really help you create a beautiful, healthy lawn. This will have all your neighbors in envy.

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Sarah Jameson’s blog, Lawn Chick, is read by over 2 million homeowners each year and she is regularly cited as an expert source of lawn care knowledge by major publications. Her goal is to meet you where you are, and help you achieve a yard you’ll be proud of. Ready to take the next step toward improving your lawn? Grab her free lawn care cheat-sheet: What to Do When - Take the Guesswork Out of Lawn Care, or upgrade your garage by browsing her favorite DIY lawn care products.

7 thoughts on “How to Overseed a Lawn the Right Way

  1. Ted

    How long do you stay off the lawn after over seeding and spreading the compost? I have two young children with a playset in the backyard, and we’re always doing something in the yard. We had a patio put in a year and a half ago, and had some tree work done (lots of equipment on grass), and I’ve been having a tough time getting the lawn back in order after all that. Thanks!

    • Hey, Ted –

      Thanks for the question! It’s something everyone wonders about, and the answer is that it really depends on the type of grass you’re planting.

      If you’re overseeding with something that’s primarily Perennial Rye and Fescue you can probably get that first mow in (bagging the clippings) in 2-2.5 weeks and have light foot traffic a week after that. This is assuming conditions are ideal and you use a good starter fertilizer.

      If you are using something that is notoriously slow to germinate (like Kentucky Bluegrass), then you may want to wait a month or more.

      Now that said – we have to live our life and a perfect lawn is no good if we can’t use and enjoy it, right? It sounds like you have a nice established lawn with a problem area due to some damage, so I’d just try to bite the bullet and try to give yourself until 1 week after your first mow on that problem area so your new grass can really take hold.

      I’d recommend that you choose a seed blend with a few different kinds of perennial rye as the primary grass, supported by Kentucky Bluegrass and some red fescues (which grow a little slower, but spread via rhizome and will help your lawn fill in and repair itself over time) since it’s a high-traffic area you’re hoping to establish it quickly.

      Good luck!

  2. JB

    Hi Sarah,

    There’s an annoying amount of a variety of weeds in my front and back yards. I wouldn’t say they make up half the lawn but still more than I care to pull. I live in Toronto, Canada and have done my share of weeding, manually and with an herbicide, prior to sowing grass seeds on May 18th and June 2nd, which I now know is a bit late. I fertilized and water reservedly as we are still getting rain. The results are a bit disappointing so far, given my poor timing, as the weeds are winning the race against my lousily germinating grass. I’m hoping this will turn around at the end of August, when I plan to overseed again if it doesn’t. I seeded over bare patches and existing grass alike. My question is: Is it really possible to completely choke out weeds by overseeding in a lawn like this? I also have a good amount of moss mixed with grass in my shaded areas and not sure if I should consider them thatch and scrape them altogether before seeding. Thank you.

    • Hey, JB!

      Great questions – thanks for the comment.

      Regarding overseeding a weedy lawn – yes, you can get good results, but it may take a couple of seasons. Late August or Early September is really the time you want to do it in your climate. If you can thicken things up with turf grass as annual weeds begin to die out for the season you’ll be able to knock them out next spring with pre-emergent. You’ll still have some weeds, but you should be able to spot-treat with herbicide and hand-pull. When you overseed this fall I recommend that you aerate and/or dethatch beforehand, and spread your seed heavy (3 times the recommended rate). This way you are ensured good thick coverage. I also recommend you use a blend of seed for your northern / cool season lawn – something with perrenial rye that can germinate quickly and that will be quick to fill in next spring. A blended seed will help ensure you have good coverage in shady and sunny areas of your lawn (the seed that thrives in those conditions will become dominant in that area of your lawn). I have an article about overseeding a weedy lawn which may be helpful (here’s the link) and another specifically about aeration before overseeding (here’s that link).

      Regarding moss, dethatching can certainly help with that, but even a little bit of moss can fill back in. I have a long article all about moss in lawns that you may be interested in when making the decision about removing it, living with it, and tips to get the most out of that part of your lawn either way. Here’s that link.

      Good luck! Hope this is helpful as you get set for your big project this fall.

      • JB

        Thank you very much! These are very helpful.

        I actually went door to door years ago aerating lawns for a summer job fresh off of high school 🙂

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