It happens to all of us: You planned to cut the grass, but it’s wet from an overnight rain. It’s certainly tempting to fire up the mower anyway, but think again.
There are good reasons why you shouldn’t mow wet grass: It can damage your lawn and your mower, and an accident can inflict serious injuries or worse. Read on for more reasons to wait until the grass dries, and a few tips on dealing with some common problems.
But, if you NEED to mow wet grass because it won’t dry out from constant rain, check out How to Mow Wet Grass.
In this article:
Uneven cuts damage your lawn
Increases risk of lawn disease
Damages mower
Presents safety hazards
Clumping creates thatch problems
The weight of the mower compacts soil and creates ruts
Grass doesn’t mulch or bag well
FAQ
Uneven cuts damage your lawn
To get a good cut, grass blades should stand upright. But wet grass blades clump and bend over, so your mower tears them, misses some patches, or pulls out grass. So, instead of a manicured lawn, you get a messy one.
Increases risk of lawn disease
Kris Lord | Flickr | CC BY 2.0
When grass blades are torn, the combination of damage and wet conditions can allow fungal diseases to take hold. A few common ones are:
Dollar spot: Creates small, silver-dollar-sized spots of straw-colored grass.
Rust disease: Causes orange or yellowish spots.
Brown Patch: Causes irregular circles of brown grass
Anthracnose: Causes reddish-brown patches
Leaf spot: Causes small brown spots with darker brown or purplish-red borders
Red Thread: Causes reddish threads of fungus on the tips of grass blades
If your lawn has signs of disease, don’t mow when the grass is wet, says Dr. Aaron J. Patton, Professor of Horticulture and Turfgrass Extension Specialist at Purdue University.
“A few plant diseases can be spread by equipment when the turf is wet, such as Pythium blight that occurs during hot, humid mornings in the summer,” he says. “If you see active disease in the morning, wait until the turf dries and mow your grass in the afternoon.”
Damages mower
tab62 | Adobe Stock
You wouldn’t think so, but cutting wet grass can be hard on your mower. Wet grass clumps and the clumps lodge in the mower deck, restricting airflow and jamming the blades. Either can strain the engine, causing it to overheat or stall.
Mowing sticky, wet grass can also dull your mower blades. This means you’ll need to replace or sharpen the blades more often.
And while it’s tempting to let that built-up grass in your mower deck dry before cleaning, that moisture will seep into the components, eventually rusting them.
Presents safety hazards
Lawn mowing is a common chore, but it carries some risk. The U.S. Consumer Product Safety Commission estimates that every year, 80,000 people end up in the ER with a lawn mower-related injury. But mowing on wet grass carries its own risks:
Wet grass is slippery. It can be hard to control the mower and keep your footing, especially on slopes and uneven ground. A fall can send you to the ER with a sprain, a cut, or a devastating injury should you land too close to the mower blade.
Riding mowers can lose traction on wet grass. A slip or skid could throw you off the mower.
It can be hard to see things in wet grass, especially if it’s high. So, you could hit — and create a projectile from — a dog toy, a sprinkler head, or the blade that broke when you hit something.
Corded electric mowers come with safety features, but using one to cut wet grass puts you at risk of being burned or shocked if water gets into the electrical connections or a frayed cord touches wet grass.
Clumping creates thatch problems
It’s hard for a mower to properly cut wet, clumpy grass, so it tends to leave those clumps out on the lawn. If they aren’t removed, they’ll decompose, killing the grass underneath.
The decomposing clippings and grass will create thatch — a layer of material that builds up on the soil and prevents water and nutrients from coming through.
Tip: Purdue University’s Department of Horticulture and Landscape Architecture suggests a couple of things to help prevent thatch buildup:
Double-cut the area. That will reduce the clippings and spread them more evenly.
If there are too many clippings, bag them to use as compost or mulch.
The weight of the mower compacts soil and creates ruts
Infographic by Juan Rodriguez
Running a lawn mower — and especially a riding mower — over water-saturated ground presses down and compacts the soil. Then, it’s difficult for air, water, and nutrients to reach grass roots, so your lawn will suffer.
Mowers can also create ruts as they move through the soft soil. This creates other problems: Uneven ground is difficult to mow, and stepping in or tripping over a rut can cause injury. If the ruts are deep, they can hold rainwater, making them a dandy breeding site for mosquitoes.
Grass doesn’t mulch or bag well
Wet grass can affect the performance of your mulching and bagging mowers:
Clogging is prevalent with mulching mowers. The wet clumps tend to collect on the mower deck and clog the blades and the discharge port. So, you’ll likely have to interrupt your mowing to clean the deck. Don’t know how? See our article, “How to clean a lawnmower deck”.
That sticky, wet grass will also collect under the deck of your bagging mower, clogging the discharge chute and the bag. Even if clippings make it into the bag, wet grass is heavy, so the added weight will put more strain on the mower; pushing it will put more strain on you.
If you’re thinking about removing your mower’s bagging attachment, the University of Missouri Extension urges you to be careful. Many bagging attachments affect mower safety and performance, so consult your owner’s manual first.
FAQ
When can you mow after the rain stops?
A rule of thumb is to wait at least 24 hours before you mow. To be sure, test for dampness by walking across the lawn. If your steps leave visible footprints, it’s still too wet. If the grass springs back up, you’re good to go.
What if you must mow wet grass?
For those of us who live with spring deluges, cutting wet grass is better than cutting foot-high grass. To minimize stress on the lawn and your mower:● Go slow: This reduces clumping and helps the mower cut more evenly.● Raise the mower height: Short cuts increase clumping and damage. ● Make sure the mower blade is sharp.● Use a side-discharge mower if possible.
Can you use a cordless mower to cut wet grass?
Some cordless mowers are water-resistant, but most manufacturers advise against cutting wet grass with their products. For example, owner manuals for both Stihl USA and LawnMaster products specifically say not to do it. A cordless mower’s battery and electrical parts aren’t waterproof. So know that if you use a cordless mower on wet grass, you’re risking a short circuit or other major damage.
Need mowing help?
If your schedule doesn’t give you time to mow when the grass is dry, Lawn Love can connect you with experienced professionals in your area who can handle your lawn mowing needs, as well as weed control and lawn aeration.
Main Photo Credit: GAGO IMAGES | Adobe Stock
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Lawn Care Calendar for Warm-Season Grass
How Long Does It Take for Burnt Grass to Grow Back
When is the Best Time to Mow Your Lawn?
Lawn Care Calendar for Cool-Season Grass
Linda Wolfla-Thomas
Linda Wolfla-Thomas is a writer based in the Midwest. In her spare time, she enjoys traveling and reading, and is still looking for the secret to growing bell peppers. Posts by Linda Wolfla-Thomas
