Lumpy-bumpy lawn – causes and fixes (How to repair a bumpy lawn)

One call we get a lot of in the Spring is “My lawn is really bumpy and uneven. Can you roll my lawn for me?” On the heavy clay soil we have in the GTA, nothing short of a steamroller can exert enough pressure to flatten a lawn by force. And if you did manage it, the soil would be so compact it would choke your grass to death anyway.

Lumps, bumps, holes and dips will show up on every lawn sooner or later. They happen for many different reasons throughout the year. Finding the right long-term-fix depends on the cause of the bump.
In Spring, bumps often appear as frozen, dense clay soil thaws unevenly. It  heaves and buckles like a bunched-up carpet.
Animals, both wild and pets sometimes dig holes in lawns. So do children at play, depressions can be created if people or animals walk on lawns that are too soft (like in the early spring or after long rains).  Some home gardening equipment can leave holes as well if misused.  Sometimes, just filling the disturbed soil back in and topping up with a good topsoil (hopefully weed-free), is a good repair for these holes. If they’re small the existing grass can grow over the hole. Larger spots should be seeded or even patched with sod.

If part of the lawn sinks and creates a depression the first thing to do is determine why. Removing the cause before correcting the effect is crucial. For any depression an inch or more deep, repair should involve removing the sod, correcting the cause of the sinking, and then back filling with new soil with enough extra to allow for settling. The removed sod can be put back in place if it is still in good shape, or replaced with new sod or seed. A shallow depression in the lawn – less than an inch deep – can be corrected gradually by sprinkling top dressing over it. Compost based mixes are good for this.

A very common problem is that people often perceive a lawn is bumpy when it has nothing to do with soil!  The lawn is made up of layers, for simplicity, lets say: the soil, roots, thatch, and the blades.  Thatch is the area just above the soil, that protects the roots.  It is normally about 1/4″-1″ in height of matted decomposing grass clippings and generally dying old grass plants that fade away as new plants are generated.  When you have a thin lawn or a disease or insect problem that is weakening an area (think Chinch bugs), the blades go first, then the thatch rapidly decomposes leaving bare soil. This bare area then erodes even deeper with rainfall, wind and activity. That leaves a depression when compared to the surrounding area of healthy lawn.  This is what we describe as the illusion of a bump.  Multiply that by several areas and voila! You feel like you have a bumpy lawn!

Bumps and rises also need to be diagnosed before correction. If caused by an object, it will need to be removed. If a bump is from burrowing animals they will have to be removed before the area can be smoothed. It may be possible to flatten smaller bumps by stepping on them.

The best way to correct and create a lawn that has very few bumps, is really quite simple- Ensure you have a green thick and healthy lawn. Your lawn care program should include  high-end nutrition components that thicken and fortify your grass plants, regular aeration to loosen the soil and lessen heaving, overseeeding to thicken the lawn and create a stronger more pest resistant lawn, as well as proactive insect control for Grubs and Chinch bugs.

Spring is the best AND worst time for people worried about lumpy lawn.  The ground is soft and grass grows quickly to cover any repairs, but snowmelt-saturated soil plus traffic on your lawn add up to new bumps.  You can read more in our April checklist. There are tips to avoiding creating ruts from lawn mower wheels when you mow the lawn in our lawn cutting tips section as well.

56 Responses to Lumpy-bumpy lawn – causes and fixes (How to repair a bumpy lawn)

  1. breathofdeath says:

    Then you got the “mother of all dew worms” invading your property. “Dew” worms appear after a heavy “dew” or a rain so they don’t drown. They eat and poop dirt so it passes right through them as they travel in the dirt. More like a condom with a hole at both ends. Or a thin skinned tube of spagetti. They don’t leave much of a hole behind besides these holes is what they call aeration. Better the worms do it rather than you running around the yard with a hay pitchfork making holes in the soil so the roots get air.
    You could try watering less. Worms disappear if the soil is too dry. for them. I water once every 3 days and lawn is happy.

  2. Reacee says:

    My Husband and I are in the process of purchasing our
    First home. A portion of the side lawn has a large
    Hill-like mound/bump. It’s almost scary to look at. Can you
    Offer any insight as to what the cause could be?

  3. Pingback: LUMPY BUMPY LAWNS: Rolling not a good idea for lawns | LawnSavers Blog

  4. S. Deshotels says:

    My lawn has hundreds of depressions, some with dead grass at the surface;others are are covered with grass (St. Augustine) Most are aprox. 8 inches in diameter. Some are much larger. Some are linear. There is no mound, dirt, or grass dug up around these depressions. They are deep enough to cause someone to trip or sprain/break an ankle. I do not see evidence of fungus or insect. The descriptions on voles or moles don’t seem to match. My husband fertilized twice early spring to get rid of buttonweed, which is still an issue. Could the possiblity of an uneven spread have caused this? What about the depressions with live grass, though? Any suggestions would be appreciated.

    • Kyle Tobin says:

      I’m not very familiar with St Augustine grass, but some of the same principles will apply.
      How deep are the depressions? are they approximately the same depth as the thatch in a healthy stand of turf? If so, the issue is likely to do with an insect or disease killing the turf in areas, hence the illusion of a depression in the underlying soil…

  5. jeff says:

    I have a yard that was put in 2012 sod. During last years summer it was dry so, we did not water often enough to keep the grass lush green. In the process, we had dry spots come up making the yard uneven little bumps while mowing. Should i re seed the yard? Or put soil down in those areas then seed it? Thank you, jeff

    • Kyle Tobin says:

      Unfortunately Soil may not cure the problem. It depends on the depth of the depressions in your lawn. Keep it properly watered, fertilize well, Maintain it regularly with alternate mowing patterns, manage the weed and insect infestations and you will develop a thicker lawn with less (perceived) bumps. Let me know how it goes! Adding compost and seed after a good double aeration will definitely help!

  6. Louise Rutland says:

    Hi. I would describe my lawn as undulating rather than bumpy as the areas of different heights are a few feet in area, but still severe enough to twist an ankle. It could not be fixed by suggestions I’ve read on here so needs a total overhaul.

    Given i don’t need a Wimbledon quality lawn my question is therefore whether to just dump a load of top soil over the existing grass, level and reseed or hire a rotovator or other machine to churn off the grass first?
    Thanks
    Louise

    • Kyle Tobin says:

      if you are looking to completely renovate the lawn, I would first use a vegetation killer to ensure you kill off the offending species of grass, and then grade the lawn. Its always a great idea to add organic matter to the existing soil and work it in. BUT, please don’t use regular old topsoil and the mess of weed seed and weedy grass seeds that come with it- you’ll be worse off!

  7. Don says:

    A bumpy lawn has been a characteristic of my lawn for many years. It’s that way year-round. There’s no sign of bug problems as the grass growth is consistent across all of it and as long as it gets adequate water, it grows well and the roots seem deep in the soil (about 3″). The spoil is sandy loam – no clay. I normally mulch it when I mow& fertilize 2-3 times a yr.

    I’ve tried top-dressing it but the soil ends up in the thatch of the high spots (bumps) as much as in the low spots, so it’s still bumpy after all the raking to distribute the soil.

    Could it be just the different growth patterns of the grasses in my turf? I have re-seeded over the years with various seed (incl. tall fescue). Would it help to mow the lawn really low, to get to (lower) the thatch part of the higher bumps and then top-dress & seed? Or will it just grow back the same? I normally cut the grass quite high.
    Thanks.

    • Kyle Tobin says:

      Tall Fescue will cause clumping as that is the style of its growth- this will promote further “bumps”.
      Do not scalp the lawn as that will not help.
      Different types of grass species is definitely part of the problem if they are not well interspersed.

      i would try a severe de-thatching and then power-seeding with topdressing and regular- frequent aeration.

  8. jim chambers says:

    I have large pine trees with roots that are coming to the surface causing dips and irregular lawn surface. How can I cover the roots and fill in dips? I have used sand in passed with a different lawn with clay like soil.. The soil with this lawn is gravelly. I don’t want to cut the roots, fearing I may kill the tree. Can you help? Thanks, Jim

    • Kyle Tobin says:

      Hi Jim,
      If you are trying to grow a lawn under the canopy of the trees, its really hard to do, and you’ll meet limited success. The best bet is to mulch out a foot or two past the drip line and create a uniform and neat mulch bed. (2-3 inches of mulch over a permeable landscape fabric).
      You’re right- cutting the roots wont help and will severely inure the tree. Other roots may surface anyway.
      Tree roots don’t take nicely to covering up their roots since you will limit air exchange- vital to a healthy tree. If you do try to cover, most literature says not to add more than 1-2 inches MAX.

      • Viola says:

        My lawn turned this spring to large spots size of a table area into clay , no more grass. What happened to my lawn. Several areas like this in my front lawn. How do I treat that?

        • Kyle Tobin says:

          Hard to answer without more information or pictures (location, what time of year etc.) Could be grubs, leatherjackets, heck it could even be a lawn area over a septic bed? The best way to treat is to understand what caused the problem first, before travelling down any particular road. In the meanwhile, be sure to take care of what you have with regular mowing at the correct height and a sharp blade, water properly and fertilize with a balanced nutrient package.

  9. SCOTT WIKE says:

    I PUT A NEW LAWN IN 3 YRS. AGO TOP DRESSED EITH 3-4 INCHES OF , WHAT I THOUGHT WAS GOOD. TO DATE I HACE ELIMINATED THE MOLES BUT TO CONTINUE TO HAVE LUMPS ALL OVER THE LAWN SPRING SUMMER AND FALL.
    NEED HELP.
    THANKS

    • Francis says:

      Try aerating and applying compost and sand. It may take a few seasons, but that should improve the soil texture

  10. Janice Swartz says:

    My yard is lumpy. You can see small lumps of hardened dirt almost like balls. We have a lot of clay in our soil. We are stumped and so was the local soil expert. He even sent a clump to a university ag dept and they had no idea what was causing it and offered no solution.

    • Kyle Tobin says:

      Hmm, the soil lab had no insight? You could actually test the soil by doing a jar test yourself.
      Did you inspect for worm castings?
      Are they from leftover aeration cores? (hey- sometimes the answer is simpler than we think, and we often overlook things)
      Any gravel in the soil pushed up by frost?
      consider dethatching or powerseeding, then thickening the lawn with overseeding, compost and fertilization.

  11. Melanie says:

    We bought a home last fall which had been vacant for two years. The grass is very patchy and there are also a lot of bumps. I have been told that the yard of this home used to be the best on the block. We are unsure if we should just kill what’s left and start over, or if it’s worth giving this lawn some love and care and see what happens.

    • Kyle Tobin says:

      I don’t know if I can make that decision for you, however I have learned that most lawns can be renovated, and if you do choose to start from scratch, it’s still best for the long run to use a re-seeding method. If the lawn was the best on the block, a little tender loving care should be able to resurrect the lawn to its former glory!
      Some considerations when evaluating and deciding on if you should seed vs. sod:
      Sodding tends to cost more.
      Seed allows you to customize and blend the seed varieties uniformly over the whole property while adapting the blend to area specific needs like shade, full sun, etc.
      EITHER WAY, you still have to stay off the long just as long while the new sod or new seed is getting established and rooted.
      Seeding tends to require less water because you only need to keep the seed bed moist, rather than ‘watering through’ the layer of thatch and roots that comes with the sod.

  12. bob bolduc says:

    you told one person (above) about worms causing bumps. I have the same problem. How can we get rid of them?

    • Kyle Tobin says:

      Hi Bob, Make sure you are fertilizing well, aerating the soil, using a weed free compost, and if needed, in early spring or late fall, use a de-thatcher run in at least 2 directions on your lawn. This will help! An alternative to dethatching is a power/slit seeder.(same concept, except one inserts seeds and has much stronger blades). For what its worth, Worms actually aerate your soil at no charge (and no back pain).

    • Kyle Tobin says:

      I doubt it. Make sure when thatching you do a cross-hatch pattern. A well-cared for lawn rarely becomes thatchy and bumpy. Top-dress with dry granulated compost, aerate and overseed, apply a high quality slow release fertilizer, then limit activity on the lawn for the next few weeks except for mowing and watering activity. it should get better.

  13. Kim Smith says:

    We have a 9month old yard (new construction home) that was laid with fescue sod (SE TN area). The dirt was graded prior to laying the sod but the landscaper did not do the best job regarding trimming and piecing together the sod squares. He had to come back and replace some squares 2 months later because his crew didn’t remove gravel from the sidewalk area before laying the sod. The yard is now horribly lumpy (my mower bounces continually when mowing) to the point of causes a few sprained ankles. We have a yard company doing regular fertilization/weed control etc. Is there something I should have them do to help correct the situation?

    • Kyle Tobin says:

      Its not easy.
      This situation is usually caused by sod not being laid properly.
      1. All pieces of sod need to be touching and snugged together without overlapping.
      2. This can happen when the watering of the new sod isn’t being performed correctly;
      a) it does not begin right away and/or
      b) there is too long of a gap between subsequent watering episodes before the sod takes root.

      The reason for this is that the sod pieces will actually shrink and come apart.
      All new sod should be watered within 15-30 minutes of being laid, or you risk it drying out and injuring the turf.

      How to fix? it will take a lot of work, but can be done. Get some fine screeded topsoil (not loam or triple mix), we want it to stay put, and be firm.
      mow your lawn first (a bit shorter than normal this time) so you can see the gaps. Fill each of the gaps with the topsoil, sprinkle seed of the EXACT same variety of the sod (or else you will create a patchwork quilt look) step on the soil and seed with your foot to level and compact it, then keep it moist!

      Laying sod on gravel is just darn laziness!

  14. Austin says:

    Hello all, first off my lawn is very soft and lumpy due to a mole/vole/gopher problem and the way my yard drains. I have read all the tips but can’t seem to locate a definite active tunnel to set a trap. I also think I killed some of the bermuda spraying 2-4-D & round-up in mid to late March. So after I get the moles under control I need to smooth and reseed my yard. What would be the best approach to getting the yard looking great? I’m looking for a list and order to do things hopefully.

    • Kyle Tobin says:

      Round-Up kills everything it touches. it is a non selective vegetation control which essentially means, it doesn’t care what type of plant you are, it’s going to kill it. Never use it on a lawn unless you are planning to start from scratch.
      Step one: Get rid of the gophers or moles, AND correct the drainage issue or else you will always have ongoing problems.
      The next step depends on what you have left on your lawn. Preparing a soil bed for turf growth could involve using a box rake, drag mat, rototiller, bringing in new soil, etc.
      Step three is seeding or sodding with the best variety of turf seed suited to your area, and taking care to ensure it is established properly.

  15. dawn says:

    help there needs to be a book how to do landscaping and lawn care for dummies lol. mt front and back yard is littered with dandelions so a neighbour gave me killex they are all dead now but you dont see grass you see dead weeds and yes have the lumps through out the lawn after i killed the weeds whats the next step. I also had to spray an ant killer because that too was littered in my lawn last year i had 11 ant hills that i could see that stuff seemed to worked ive stepped on these ant hills and nothin so far

    • Kyle Tobin says:

      Its not as hard as you think. if the weeds are under control (including the weed grasses- those may need a vegetation control), it’s time to promote what you want to see. time for a lawn renovation. Start by amending the soil with a high quality dry granulated compost, then aerate the lawn in 2 directions (or more if you can), then Power/slit-seed the lawn; then keep it moist (not soaked) until the grass seed germinates. you may need additional seed in the fall for some small bare areas. be sure to mow regularly at 2 3/4″- 3″ every 5-7 days to encourage thick growth, and be sure to FERTILIZE. Once the grass is established, ensure you water it once a week to provide 1″ to the soil. You’re no dummy, as long as you stay committed to regular care, you’re on your way to writing the book!

  16. Jo says:

    Our lawn is lush and green, but when you walk on it, it’s like walking on small golf balls. No signs of moles or voles. How can I fix

    • Kyle Tobin says:

      What type of grass species do you have? I would dig up a small patch (maybe 20 cm x 20 cm with a spade shovel) about 15 cm deep and investigate the soil texture. What do you see? Is their gravel or other large lumps?
      Otherwise, It could be worm castings. These generate small hills the size of golf balls. Worms are great for your soil, but some years create more bumps in our lawn than we can normally put up with.
      Make sure you are fertilizing well, aerating the soil, using a weed free compost, and if needed, in early spring or late fall, use a de-thatcher run in at least 2 directions on your lawn. This will help!

  17. Mary Smith says:

    Sure wish you had posted a reply to S. Deshotels – July 3, 2014. We have the same problem, in Fl, scared to death it indicates a sink hole (or several sinkholes!) – so an answer here would have greatly helped us! 🙁

    • Kyle Tobin says:

      I’m sorry. I just did respond now. Although I’m aware of the sinkholes from the news, I’m not an engineer or equipped to prognosticate on sinkholes. If you think you have a problem with sinkholes, I would engage a soil engineer pronto!

  18. Danny May says:

    Hello,

    I layed sod in my yard. Had the lawn soaked and the dog got out and ran around on it. Left a bunch of divots everywhere, and some of the places where the sod met up, it feels uneven. Whats the best way to tackle this? Should I get it wet and roll it?

    • Kyle Tobin says:

      That is probably a good idea if the sod is still fairly new. The good thing is, that it should already be soaked all the time right now. Pay attention to those seams and keep them mice and tight- that’s the first place that weeds start to grow later on. Make sure you walk flat footed!

  19. Brent says:

    Man my back lawn had little crabapple sized bumps everywhere. So dense that I can step on 2 with every step. It is getting progressively worse as time goes on. It wasn’t that bad last year but there were some.

  20. Mark says:

    Hi there. I have 4 spots on the lawn where there used to be circular stones across the garden. After replacing these and trying to level the soil and seed, i was able to grow the grass fine, however, the soil has sunk and the depressions are still about 2-3 inches. The problem is when mowing, as these sections have very long grass compared to the rest, and at time the mower will slip into the gap and bald sport areas around them. To fill in the spots with soil would mean burying the grass. Would this just kill the grass, meaning im best just re-seedng again, or is there another way, like slowly layer the soil over time to level it to the same height as the rest? Thanks

    • Kyle Tobin says:

      I’d either fill it all at once and sprinkle some seed, or cut an ‘x’ through the area, peel back the sod, fill with topsoil and then lay back the existing sod. Alternatively, cut out the area entirely, and after back-filling, re-sod that area.

  21. Pete says:

    I’ve learned from your advice that my lumps are probably caused by worms. Is there a product you recommend to eliminate them ? I’d rather rely on frequent aeration and get rid of the lumps–before I break an ankle. Also, have you had any experience with Tenacity to selectively get rid of bentgrass ? My lawn is on Cape Cod, Mass. and I’m pretty sure was originally planted in 1983 with a Cape Cod mix.

    • Kyle Tobin says:

      Earthworms are great for your soil, a natural aerator, please don’t try to kill them! Tenacity will help with bentgrass and other annual weed grasses. Be sure to follow the label!

  22. Plumber says:

    It’s awesome to pay a quick visit this website and reading the views of all
    colleagues on the topic of this piece of writing, while I am also zealous of getting experience.

  23. Anthony Russo says:

    Hey thanks everyone’s for your time on this matter my lawn is raising in big bumps, I mean like my back lawn has rising about anywhere from a couple inches to almost a foot and the bumps are big, one is three feet wide and is about twenty feet in Length. I tied a line from one post another and keep record to see how much it grows. the mound has rising to the string I put in post and the string is real loose I have dug down about five feet in the middle of the bump but I’m not getting anything the soil is wet down there too like I said these mound’s are coming up all over my back yard house and back yard has a tilt towards the street . I’m just at a loss don’t know what the heck is going on. Thanks

    • Kyle Tobin says:

      That is definitely strange! Haven’t heard of that happening on any lawns? I would call the city and ask them to send out an engineer to see if there isn’t something more sever going on with the geology surrounding you… How high is the water table?? Is the soil disturbed? What is the history of the site?

  24. Jackie says:

    Hello,
    My lawn is about 11 years old and now for some reason the east side of our house is almost impossible to mow due to all the bumps. The best way I can describe the bumps is that the lawn now feels like a herd of cattle or horses walked on the grass after a long soaking rain and now it is dry, leaving all the “ruts” , so to speak. We have aerated it but nothing changed. We keep it fertilized and water every other day in the summer. No other part of the yard is doing this…and we have a huge yard. It’s the point that I can’t even keep the mower (I push mow) in a straight line due to all the jumping around it does because of the bumps.
    Help!

    • Kyle Tobin says:

      It really depends on how the bumps got there in the first place. In some rare situations, lawn rolling may be your best answer. Make sure to do it on a well watered lawn, and then stay off it afterward. You will need to ensure regular aeration , topdressing and seeding is followed to promote a thick lawn that will have less a chance in getting to that situation again.

      • Jackie says:

        Kyle,
        I went out and actually dug up several of the bumps and found that there are holes under them that are the size of my little finger! These are earth worms doing this, aren’t they? I don’t like to be mean, but my yard is actually unwalkable now so can you give me the name of some sort of solution to put on this part of the yard to get rid of them? Would grub granules work? We will power rake it in the spring too.
        thanks for your help.

        • Kyle Tobin says:

          Its quite possible they are earth worms, they do create mounding, but it look s like dried (formerly liquid) mud that creates the mounds.
          Earth worms are not a lawn pest and not susceptible to grub controls. (the grub is the larvae of a beetle and looks completely different than an earthworm).
          Earthworms don’t normally cause un-walkable situations. I’m not sure this is the culprit.
          Can you send some pictures of the area and close up?
          There are so many possibilities that may not have been considered. What is the site conditions? Where are you located? what is nearby? etc.

Leave a Reply

Your email address will not be published. Required fields are marked *