Why is My Lawn Lumpy

Why is My Lawn Lumpy?

A lumpy lawn is an eyesore at best and a health hazard at worst. Noticing strange lumps in your lawn is concerning. It makes mowing your lawn challenging and your yard is less comfortable to use to relax on with your family or while entertaining. Why is my lawn lumpy? Well it depends. Figuring out why your lawn has lumps is key to understanding how to fix the issue (and keep it from coming back).

Trust and Accuracy Information

This article was last updated on by Lawn Chick Owner Sarah Jameson
Article content reviewed for accuracy by Horticulturist Arthur Davidson, A.S.

Having a lumpy or bumpy lawn is a problem for a number of reasons.

Even if your yard looks okay from a distance, walking on it or mowing it might be uncomfortable or difficult. If your lawn is severely lumpy, you might find that it is hard and it might even be painful to sit on.

Holes from digging animals or lumps from filling in those holes can even be a potential tripping hazard – especially if you have young children who don’t always watch where they’re running (or have great balance).

Lumpy Lawn

In this article, I’ll go over each of the possible causes of your lumpy lawn. I’ll also tell you how to level it step-by-step. What’s more, I’ll provide some tips to address each type of issue you may have in your yard (to keep it nice and level for years to come).

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Why Is Your Lawn Lumpy? (Common Causes)

There are several common reasons why your lawn is lumpy. These include heavy foot traffic in certain areas (which causes soil compaction), damage from tires and heavy equipment, lumps from tools, toys, pet waste, and other organic matter getting buried in the lawn, and even improper mowing. The good news is that correcting this issue and leveling your lawn can be done in a weekend.

Let’s take a look at more potential causes for your uneven lawn below. Then I’ll tell you how to fix it.

Your Lawn is Old

If your lawn is quite old, it may have gradually taken on an uneven and lumpy appearance over time.

This is a result of the turfgrass thinning out and compacting. As seasons pass, the freezing and thawing cycle “heaves” or elevates parts of the soil.

Why is My Lawn Uneven and Lumpy

Roots from trees grow beneath it, pinecones and twigs get buried in the grass, and the same is sometimes true of tools and toys that get left behind in your yard before winter.

Soggy Soil

Soil that stays too mushy and wet can easily be compromised when there is pressure on top of it.

If you have something (a truck, trailer, or heavy mower) or someone (a husband on a bike) with a lot of weight moving over the lawn you will end up with ruts and uneven turf. This is one reason I don’t recommend mowing your lawn when it’s very wet.

Sometimes animals or people walking on your lawn during times when the lawn is very soft can lead to depressions, as well.

Try to avoid a lot of activity on your lawn after significant rain or in the early parts of spring.

The Wrong Kind of Mowing

That’s right, mowing your lawn the wrong way can also lead to lumpiness. One common problem is if you use the exact same pattern on every occasion that you mow.

Mowing the Wrong Way Can Make Your Lawn Lumpy and Uneven

The weight of the wheels of the mower and the path of your footsteps can push down and eventually compact the soil over time.

It’s good to have at least two mowing patterns that you can follow. This way you can change it up every time you mow.

Tree removal

When you remove a tree from your yard you can have a couple of potential issues left behind.

If you have the stump cut flush with the turf that can be a high point in the yard as it decomposes over time. If you pay to have the stump ground up, you’ll often be left with a depression in the lawn. Either way you’ll probably have lumps in your yard.

Any wood still under the ground will rot over time. As it rots, the ground will dip, causing depressions or even holes (which can be a safety hazard).

Heavy Equipment on Your Lawn

Heavy equipment driving onto your lawn or sitting on your lawn for any period of time will put too much pressure on the turf.

Heavy Machinery or Equipment Driving or Parked on Lawn Can Cause Unevenness

This will produce depressions and ruts.

It can compact soil that then form low spots. This can be caused by equipment that has hydraulic platforms necessary for stability, or even parking a boat trailer on your lawn for an extended period of time.

How to Fix a Lumpy Lawn

 If the situation is especially bad, you might want to consider ripping up your lawn, regrading, and planting a new one.

Before you invest in something like that, consider that there are other things you can try.

Top Dressing Your Lawn to Level It

You can apply top-dressing to your lawn (about 1/2″ to 1/4″) every year.

This allows you to improve your soil, help your grass grow thicker and healthier, and level your turf all at the same time.

Top Dressing and Leveling Your Lawn

Top dressing your lawn is a simple process that can be done as part of a big fall project weekend, combining the project with core aeration and overseeding.

Early fall or early spring is usually the best time of year to do this.

Preparing Your Lawn

Make sure that you cut your grass very short before you top-dress. Shorter grass lets you more easily see and identify lumpy areas, and it makes it easier to work your soil, compost or sand evenly over your yard.

Next, use an iron rake, thatch rake or power rake to get rid of thatch.

Using a Power Rake to Dethatch Lawn Prior to Leveling It

Thatch is a layer of plant matter stuck to the top of the soil. It can block out the benefits of water and air from getting into the soil. This adversely affects the health of your grass.

If you have a big yard, consider renting a dethatcher for a few hours. Your back and arms will thank you. Home Depot does 4 hour rentals which is plenty of time to do most yards.

For mid-sized and smaller yards, buying is probably a better choice. There are a few electric models that are excellent and don’t cost much more than renting a power rake.

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.

Spread Top-dressing on Your Lawn

Evenly spread a layer of topsoil across your lawn. Often you’ll bring the material to your lawn in a wheelbarrow, dump it in piles, and then you can come back with a rake to spread the material out from those piles.

Spreading Top-Dressing On Your Lawn to Remove Lumps and Smooth it Out

There are a few different materials you can use to top-dress and level your yard. These include:

  • Topsoil or Loam
  • 50/50 Mix of Compost and Loam
  • Screened Compost (my favorite)
  • Sand

Each material has different benefits and will benefit your yard in different ways.

If you have heavy clay soil, adding some sand can help improve drainage and is easier to level. If you have sandy soil, adding loam and/or compost will help retain moisture so you have to water less.

Top-dressing can simply be a matter of shoveling out your material into low areas and then spreading it out evenly to fill in depressions until your yard is level. Just remember to be aware of grading – you always want to be sure water drains away from your house.

Leveling Your Lawn's Lumps by Top-Dressing it

You can go over areas multiple times until you’re satisfied. Spots with severe depressions should have new seeds planted as part of the process. A heavy layer of soil could smother your grass and give weeds the opportunity to take root.

A Few Tools That Can Make the Project Easier

While you don’t need any of these tools to level your lawn, they can make your project go quicker and improve your results, so I thought I’d mention them:

  • An Electric Dethatcher (Amazon link) – For a bit more than the cost of renting a dethatcher, you can buy a quality electric model and a long heavy-duty extension cord. If you plan to dethatch a few times over the coming years, this can be a really good investment and save you money in the long run.
  • A Lawn Leveling Rake (Amazon link) – Something like this can really make it easy to get great results while spreading sand or soil over your yard. It’s not necessary – you can get good results with a rake you have in your garage, but it will save you time and deliver better results.
  • A Compost Roller (Amazon link) – Spreading topsoil, or compost over a large yard by shovel can be a back breaker, and investing in a roller like the Landzie can make spreading the organic matter over your property easier and allow you to get nice and even coverage which will save you time with the leveling rake.

What Experts Say About Taking On This Project

Zac Reicher at the Department of Horticulture & Landscape Architecture, Turfgrass Science at Purdue University offers some advice on using topdressing to fix a bumpy lawn. As Zac explains, in most cases, your lawn is “bumpy because of the natural settling of soil over time.”

That is why it’s so effective for lawn care professionals to “apply thin layers of sand or soil over finely manicured turf and then use modified brooms to move the topdressing down to the soil surface.” 

Over at Iowa State University, Richard Jauron at Extension and Outreach says that core aeration and power raking are effective for helping deal with a lumpy lawn. He recommends starting “by core aerifying the lawn.” After that, go ahead and use a power rake. 

Richard reminds us not to use a heavy roller on bumpy lawns. If you do, you could end up making your soil more compacted. 

I Agree: Be Careful About Using Heavy Lawn Rollers

Some homeowners assume that a heavy lawn roller will be an easy solution to their bumpy lawn problem.

This isn’t true and will likely cause even more compaction in the soil. In my experience these tools (which are often used by professionals) can do more harm than good if used improperly. I don’t recommend rolling your lawn unless you have very sandy soil and compaction is not an issue for your yard.

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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.

2 thoughts on “Why is My Lawn Lumpy?

  1. Dwight

    One of the most common lumpy looking lawn issues is Tall Fescue. ( I think it’s called K31 ? ). It’s not like the turf grade tall fescue used in good quality lawn seeds and it’s something most home owners ( at least up here in the cool season regions) want in their lawn. A couple days after mowing it’s already looking like a big clump in the middle of your nice lawn. Only good way to get rid of it is a non selective grass killer and re- seeding.

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