Having a sinking feeling is never a good experience, especially when you walk across your lawn. Different factors can create newly formed holes or lawn depressions, from something you could be doing to natural causes. Before you get too many sunken spots in your lawn or bigger lawn depressions, let’s look at what might be happening.
Why Your Lawn Sinks When Walking On It (The Short Answer)
If you find yourself sinking when walking across the lawn, then there’s no need to worry too much. Usually, there is a simple reason why this is happening. Here are some examples of why your lawn sinks when walking on it.
- Poor Drainage in the Lawn
- Ground Erosion
- Decaying Materials Buried Under your Lawn
- Settling Ground
- Excess Buildup of Thatch in the Lawn
- Overwatering
- Your Type of Grass
- Lawn Pests
- Broken Irrigation
9 Possible Sinking Lawn Causes
As you can see, there is a long list of potential reasons your lawn sinks when walking on it. So, let’s dig in and investigate what might be going on and how you can put a stop to it.
Poor Drainage in the Lawn
Poor drainage in your lawn can sometimes make you feel like you’re walking on a water bed. The squishy and spongy feeling in your yard can be because the soil can’t drain the water adequately. If I walk across my lawn after a rainstorm, I can definitely feel myself sinking, even though the drainage of my soil is pretty good. After a while, the water drains, and the sponginess disappears.
So, if your lawn still sinks when walking on it sometime after rain or after your irrigation has run, then you’ll want to look at improving your yard’s drainage.
Ground Erosion
Ground erosion is another problem created by rain and irrigation. Erosion happens when the water washes out loose material in the soil and creates cavities. When you walk across your lawn, you might feel these cavities collapsing. I had this problem down the side of my house where most of the water runoff from my roof would deposit. So, look where the rainwater deposits in your yard and see if it’s washing soil away.
Decaying Materials Buried Under Your Lawn
I once noticed a sunken spot on my lawn that really confused me. No obvious reasons stood out, like water erosion or poor drainage. So, I grabbed a shovel and started digging. It didn’t take long to discover a rotting tree root in the soil.
Now, if I had taken a step back and thought about the work I’d done in my yard, I probably would have remembered the tree I had removed a few months earlier. Even though I removed the tree, I didn’t remove all the roots. As soon as the roots began to rot, cavities in the soil were created, resulting in a sunken lawn. So, look to see if any work in your yard has caused the same issue.
Settling Ground
Any time that ground is disturbed, it creates air pockets. Newly constructed homes face this problem a lot. Just like decaying material or ground erosion, these cavities or air pockets will eventually collapse. Another cause of settling ground is the makeup of the soil and how it moves over time.
For example, coastal areas like Florida have soil with a high percentage of sand and a high water table. As soon as the water table lowers, so does the soil. Florida residents are well aware that this process can cause some extensive damage and sinking of their properties. In extreme cases, a sinkhole can appear that will not only suck in your lawn but can also suck buildings.
Another similar issue to settling is ground slippage. Slippage happens when groundwater loosens up the soil and allows it to slide. People living in areas such as the Pacific coastline are familiar with the effects of slopes and water. So, look at your environment and see if mother nature is causing your lawn to sink.
Excess Buildup of Thatch in the Lawn
Certain lawn types create excessive thatch. Grasses like Kentucky bluegrass, creeping bentgrass, and creeping red fescue are just a few grasses that have thatch build-up over the growing season.
Even though thatch is a natural part of your lawn growing process and helps control things like soil temperature and moisture retention, and adds natural nutrients to your lawn, it does give the feeling that your lawn is sinking. So, dig into your grass to see how much thatch you have. If it looks like there is a lot, then you’ll want to use a method to dethatch your lawn.
Overwatering Your Lawn
Water is a key element of a healthy lawn, but too much watering will make your soil very soft. You might think you have a drainage problem, but it could be down to the fact you are overwatering. Adding too much water to your lawn will make it feel like you’re sinking when walking on it. So, before heading out with the hose or your irrigation system switches on, check the moisture in the soil. You might need to adjust your watering schedule.
Your Type of Grass
We already talked about a few grass types that can make your lawn feel like it’s sinking because of thatch, but a few more grass types deserve mention. Grasses like St. Augustine grow completely differently than many grass types. St. Augustine has lateral stolons or runners that grow sideways up to about two feet long.
Now, as these runners form, they create a mat that gets thicker over time as the lawn becomes established. So, a thick St. Augustine lawn can be pretty spongy. The thicker the lawn, the more you feel like you are sinking. One way to keep the sinking feeling to a minimum is to mow your lawn at the right cutting height.
Lawn Pests
Voles, moles, gophers, beetles, ants, grubs, worms, and even bees like to make a home under your lawn. Oh, and let us not forget burrowing owls as well. With all the will in the world, keeping these pests out of your lawn can be a full-time job, even if you have some assistance from companies like TruGreen.
Any of these little pests will cause you a problem, not only with the health of your lawn but also with tunnels or cavities under your lawn. So, if you are trying to figure out what causes lawn depressions, it could be a pest under your lawn. My advice is to look at the health of your grass to see if there are any obvious signs of pests. If you dig into the affected area, you might be surprised by what you find.
In the case of owls, you’ll have to wait until they decide to leave and make a new home on someone else’s lawn since the federal government protects these little guys.
Broken Irrigation
Broken irrigation is the last item on my list of sinking lawn causes. To my frustration, I sometimes mow over and break my irrigation heads. Once the irrigation turns on, it creates a hole in my lawn. This is soil erosion in double time. Fortunately, I haven’t had a broken irrigation pipe under my lawn, but my irrigation guy tells me that when pipes break, they can wash out so much soil that you end up with a sinking lawn. So, walk around your lawn and investigate if your irrigation could be the reason your lawn sinks when walking on it.
How to Fix a Lawn That Sinks When You Walk On It
That was a pretty long list of reasons your lawn sinks when walking on it. Hopefully, one of these causes identifies what is going on in your yard. Now, let’s go over what you can do to fix your sinking lawn problem.
Fixing Lawn Drainage
There are several ways to improve your lawn’s drainage. In areas that are particularly bad and have standing water, you can install drainage systems such as French drains or lawn drains. Both of these methods require some type of excavation to install pipework and drain catch pits.
Before you grab your shovel or call in the contractors, though, you should try some deep aeration. This is a process of digging several small deep holes across your lawn. As a result, these holes allow water to pass through the topsoil and deeper into the ground. You can see some pretty quick results with deep aeration, as it allows your lawn to dry out and stop the sinking feeling.
Reducing Soil Erosion
To reduce soil erosion, you’ll need to divert the water away from your lawn. Now, the first step is to find out where the water is coming from. It could be coming off your roof, from your neighbor’s run-off, or your gutter downspouts discharge straight onto your lawn. So, once you know the source of the water, you can look at installing a solution.
For example, you can add gutters to your roof for the problem areas, dig a ditch or add a trench to divert your neighbor’s runoff, or be like the Floridians and have a swale in your lawn to store the water until it has time to soak away.
Filling in Decaying Material
If your lawn is sinking due to decaying material, you’ll want to fill in the lawn depression. The simplest method is to add topsoil to the affected area in small amounts so as not to block the sunlight from the grass.
For example, add a thin layer of soil, say ½ an inch at a time, until the depression has gone. At some point, the decaying material will completely decompose, and the sinking will stop. So, you shouldn’t have to repeat this process too many times.
Responding to Settling
Responding to settling is just the same as dealing with decaying material. Here, you just need to fill the depression with extra topsoil. Now, if you have a large depression, then you might want to consider completely filling the hole and replacing the grass. But I’d only do this with a very large depression. Adding ½ inch of soil at a time will take care of any depression, but it will take some time if you are dealing with a large hole. I’ll leave that decision to you.
Dethatching Your Lawn
There are lots of different tools to choose from to remove the thatch from your lawn. You could use a regular garden rake or a dedicated powered dethatcher. Both of these tools comb the grass and pull the thatch from the bottom of the grass, reducing the springiness that causes the sinking feeling.
Now there are pros and cons to dethatching that you should consider, and your lawn will probably look bad after dethatching, but it definitely helps firm up your lawn. So if you are trying to decide between a power rake vs. a dethatcher, then rest assured they do pretty much the same job.
Adjusting Your Watering Schedule
Many garden sprinklers need to be adjusted. You’ll need to set how long you manually operate your sprinkler or how long you set your timer to run. Whichever method you use, the aim is to get sufficient water to your lawn but not too much.
Now, you could poke your finger into the ground before you water or use a more precise method like a soil moisture tester to make sure you don’t overwater. By not overwatering, you’ll reduce the water content in the soil and illuminate the sinking and potential erosion.
Using the Correct Mowing Height
This fix is really only for warm season grasses like St. Augustine that grow lateral stolons and form a mat. Keeping this type of grass mowed between 3 ½ to 4 inches is good for the grass and reduces the sponginess. So, by adjusting your cutting height lever, you’ll be able to mow your lawn at the correct level.
Taking Care of Lawn Pests
Getting rid of lawn pests comes down to the type of pest you are dealing with. Pesticides will take care of most insects, including ants and grub, but you’ll need to get more creative with rodents.
For example, mole spikes, gopher repellents, and even an empty beer can on a wooden cane can generate a noise to scare off even the most persistent four-legged visitors. But if you find yourself struggling, calling your local pest control company for advice or assistance could be the best way forward.
Fixing Irrigation
I have a box of spare parts for my irrigation system, including a few spare heads, thread couplings, and an irrigation nipple extractor which is the tool you use to remove those snapped couplings. In addition, I service my irrigation system regularly and know how the timer works.
The last thing you want is a sprinkler timer that won’t turn off and floods your lawn. To prevent damage to my sprinkler head while I’m mowing, I installed concrete rings around the heads. The best $1 (per ring) I think I have spent in a long time. I have spare parts like pipes, couplings, and glue for bigger fixes.
However, I always have a reliable irrigation company’s telephone number on hand to save me the trouble of dealing with a fix that is too big and technical.
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