If you haven’t had a lawn bubble in your own backyard – or seen one in someone else’s – then you’ll know they’re quite extraordinary things just like blisters under the grass. If you haven’t yet come across one there’s a video below. So how do they form?
Lawn bubbles are caused by water getting trapped beneath the grass, which is unable to drain away or be absorbed naturally. When water is trapped under the root system of the grass, the turf floats on top of this water pocket forming a blister-like raised area on the lawn.
Let’s explore the subject of lawn bubbles in more detail, and find out what they are, how they form – and how to get rid of them before they potentially kill your grass…
What Are Lawn Bubbles? (Also Called Lawn Blisters)
Lawn bubbles, also called lawn blisters and grass bubbles, are raised patches of grass caused by water trapped beneath the surface. Like a blister on your foot (and sorry for the slightly unpleasant comparison here), they are soft and squashy, because they are filled with liquid.
They can be quite large (we’re not talking cute little blowing bubble size here), and if you sit on one, it feels like a water bed. Like a blister under your skin (apologies again), the surface isn’t broken, just raised and swollen.
Lawn bubbles aren’t that common on domestic lawns, and most of us never even see one, let alone have one pop up in our backyards. People who’ve experienced lawn blisters can initially feel concerned when parts of their garden start to rise; however, lawn bubbles aren’t dangerous to people. In fact, the kids will probably adopt them as impromptu trampolines.
But, you do need to get rid of them as they can damage your lawn. Also, you need to get to the bottom of what’s causing the grass bubble or bubbles.
What Causes Lawn Bubbles?
Lawn bubbles are caused by water becoming trapped beneath the grass, which is unable to drain away or be absorbed naturally. When accumulated water is trapped below the surface of the grass’ roots, the grass ends up floating on top of this pocket of water. This results in the blister-like raised area on the lawn.
There are two causes for this: heavy rainfall or a burst water pipe.Heavy rainfall is the most likely cause of lawn bubbles. Sometimes, we get those rainstorms that are so fast and furious that our yards can’t drain the water away. This rainfall can become trapped under your lawn.
This is most likely to occur if you have a layer of plastic beneath your topsoil. Unless you laid it yourself, you might never know that you have plastic underneath your lawn. In areas where the soil is poor, landscapers sometimes lay a sheet of plastic down then cover it with better-quality, imported topsoil. This is then turfed or seeded to create a nice lawn.
However, lawn bubbles can still occur even without a layer of plastic. They’re more likely to happen if you have dense, tightly growing grass. This seems like a pretty miserable reward for a thick, lush lawn.
So, now we know that rainfall is the main cause. But what if it hasn’t been raining heavily and you spot a lawn bubble? This can be a sign that there’s a broken water pipe beneath the surface. In this case, the lawn bubble is a bit of a lifesaver, as it draws attention to the leak.
Very rarely, a lawn bubble is caused by a build-up of methane. This is nothing sinister, and it’s caused by the natural rotting process of vegetation. There is also a theory that a lawn blister means a sinkhole: this is not the case (although obviously, seek expert advice if you have good reason to believe that there might be one in your lot).
Can Lawn Bubbles Kill Your Grass?
Yes, lawn bubbles can kill your grass. This happens because the water layer beneath the surface deprives the plants of nutrients.
But surely grass bounces back after a wet spell of weather? Yes, it normally does, provided the soil isn’t affected. To understand how a lawn blister can kill grass, picture what’s happening beneath the bubbled surface.
The water has forced a layer underneath the grass and above most of the topsoil. Suddenly, the grass’s roots are separated from the soil, and they are left treading water. If this pocket of water isn’t drained, the grass won’t be able to reach its roots into the soil again to draw up the nutrients it needs to thrive.
Are Lawn Bubbles Dangerous?
A typical, water-filled lawn bubble is not going to harm anything except your lawn. They do not indicate that there’s a sinkhole in your yard; although if you think the bubble is caused by a burst or leaking pipe, you’ll need to act fast.
There is one extremely rare (but very reported) incident when grass bubbles have been dangerous, and this was in Siberia in 2016. Masses of methane-filled bubbles formed in dangerous quantities, thought to be as a result of rising temperatures on earth causing the permafrost to melt.
Methane-filled pockets caused by melting permafrost is unlikely to be a factor with any blister-like activity on your lawn. However, should you Google “are lawn bubbles dangerous”, this story will come up on your results. We thought we’d better put it into a context!
How Do I Fix Blisters or Bubbles in My Lawn?
To get rid of a lawn bubble, you’ll need to drain it. Your mission is to drain the water out of the bubble, but make sure it’s channeled somewhere sensible, and also to try and do this without tearing up too much grass.
Before you drain the grass bubble, you’ll need to work out the cause. If it’s a damaged water pipe, fixing this takes priority over rescuing your grass. And to be honest, there’s no point in carrying out a neat lawn repair on an area that’s going to need more work. With these instructions, we’re assuming that you’ve checked the bubbled area and established that it’s caused by excess rainfall.
Now it’s time to drain that blister… You puncture it with a sharp gardening tool, releasing the water. Remember: the fewer holes you make, the less damage to your lawn.
Believe it or not, this video of a man draining a lawn bubble in his yard has been watched over 38,000,000 times. Just look at the amount of muddy water that’s coming out of the puncture hole, and bear in mind that that’s going to make quite a mess of his yard…
If it’s a large blister and you don’t want your lawn waterlogged like that, you can dig a channel towards a drain, which should encourage that muddy water to drain away neatly after the bubble’s been popped. However, you’re now left with a trench in your garden…
You’ve popped the bubble, the water’s gone, and your lawn has eventually dried out again. How can you treat the puncture marks (or even drainage trenches) that are left from the lancing of the blister? Filling the gaps with grass seed that’s ready-mixed with fine soil is the easiest way.
If it looks like these pesky bubbles will be an ongoing problem, you may need to consider a more permanent drainage solution for your lawn. Next time there’s heavy rain, observe where the water collects or runs away: this could be helpful information for the engineer you engage to help you with the drainage.
You may be reading this before you’ve even created your lawn. In that case, you can help to prevent grass bubbles from ever occurring by having well-draining soil. Prepare the soil by aerating it and mixing in plenty of fine sand and gravel. This allows water to flow through the soil without compacting and forming puddles.
Lawn bubbles are weird and squishy – and they’re not that easy to drain as you can see from the video above.
However, you do need to try and drain them properly or they can eventually kill your grass.
Try and keep the number of drainage holes you make to a minimum, and channel the water away from the rest of your lawn if you can – which again is easier said than done as the guy in the video soon discovers.
So if you’ve got lawn bubble trouble – good luck with it – as this is one backyard problem that’s not as simple to solve as it seems. 🙂
Homeowner and property investor Larry Jones founded Take a Yard in 2020 to bring you the very best outdoor living content, based on his years of experience managing outside spaces. Read more >