Lumpy-bumpy lawn – causes and fixes

by John E

One call we get a lot of in the Spring is “My lawn is really bumpy and uneven. Can you fix it?” Homeowners ask us if we will roll their lawn for them. 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, and some home gardening equipment can leave holes as well if misused. 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.

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.

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 when you mow the lawn in our lawn cutting tips section as well.

{ 3 comments… read them below or add one }

alan April 22, 2012 at 5:26 pm

my lawn is very bumpy from large dew worms.What can I do?

breathofdeath August 6, 2012 at 10:13 pm

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.

TEAM Bootcamp November 9, 2013 at 9:05 am

Great advice. Really helped. We have a 3 acre paddock that we use for training and it’s a nightmare.

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