Why You Shouldn’t Mow Wet Grass

wet grass with droplets of rain on it

Can you cut grass while it’s wet? Short answer: No. Whether it’s early morning and the lawn is still dewy, a rainstorm just ended, or you just ran your sprinklers, you should skip the mow for now. This article will explain all the reasons why you shouldn’t mow wet grass. 

Mowing the lawn while it’s wet can cause:

Uneven cuts

For a clean, even cut, grass needs to stand up straight as the blade slices through it, rather than bending over limply. Think of it as the difference between cutting a string that’s pulled taut vs. a loose one.

But when the grass is wet, the water weighs it down, so it can’t stand up straight. The result is that the mower blades tear through the grass messily rather than cutting it cleanly. 

Another potential issue is that the mower might miss some of those blades of grass hanging low to the ground. Then, when the grass dries, you’ll be left with long, uncut patches, and you’ll have to mow again. 

Fungal lawn diseases 

Those tears in the blades of grass will leave your lawn more susceptible to infection from fungal diseases. Fungi thrive in moist conditions, so the combination of torn grass and water lingering in the lawn all but guarantees lawn disease. 

Some common lawn fungi to look out for (especially if you recently mowed the lawn while wet) are:

  • 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

These and other lawn diseases can weaken your grass and even kill large swaths of the lawn if left unchecked. 

Suffocated grassroots 

Did you know your lawn’s roots need a steady supply of oxygen to grow strong and healthy? Mowing wet grass can cut off that oxygen supply and suffocate your grassroots, leading to thin and patchy growth. Why does that happen? There are two reasons. 

Compacted soil: When your grass is wet, your soil is wet, too. Rolling your heavy lawn mower across wet soil causes compaction, which means oxygen can’t reach the roots. The wheels can also cause unattractive ruts in wet soil.

Clumps of wet grass: Cut wet grass tends to clump. Your mower leaves these large clumps of clippings behind in the lawn, where they block airflow, water, and sunlight from reaching the living grass.

Lawn mower damage

Clumps of wet grass not only hurt your lawn. They also clog your mower blades, slowing them down and making the engine work harder to turn them. Electric lawn mowers, which have less torque than gas mowers, often can’t cut through wet grass at all for this reason.

Plus, the wet grass will stick to the underside of the mower, making it much harder for you to clean. And all that moisture can rust the mower’s blades and other metal parts. 

Danger for you

Mowing the lawn wet is a lot riskier than it’s worth. The biggest risk is slipping and falling. No matter how much traction your sneakers have, they’re no match for slippery wet grass. Falling on its own would be bad enough, but falling while operating a machine with spinning blades is even more dangerous. 

Then there’s the added danger of electrocution if you’re using an electric corded mower. If your extension cord is damaged at all and the bare wiring comes in contact with the wet grass, you’re in trouble. 

Mowing a wet lawn puts your clothes in danger, too, because cut wet grass stains much worse than dry grass. 

FAQ about cutting wet grass

How soon can you cut grass after rain?

Wait until the grass is dry, which will usually take at least a few hours. Walk through the lawn before mowing, and if your shoes or feet come away wet, don’t mow yet. If they’re mostly dry, you should be good to go. 

What if you have to mow a wet lawn?

In some cases, you have no choice but to mow the lawn while it’s wet – like when it rains for months on end without a break. 

If you absolutely must cut wet grass, follow these tips to minimize the damage:

Sharpen the mower blades right before mowing. Sharp blades are more likely to make a clean cut, and wet grass needs all the help it can get in that department. 

Raise the mower deck to higher than usual so the wet grass clippings are smaller and less likely to form large clumps. 

Discharge the grass clippings instead of mulching or bagging. Mulching doesn’t work well on wet grass, and the wet grass would get caked onto the inside of the bag. 

Stop and clean the underside of the mower periodically as you go so the blades don’t get too clogged and the layer of caked-on grass doesn’t get too thick.

When is the best time to mow the lawn?

The best time of day to mow your lawn is mid-morning, after the morning dew has dried but before the hottest part of the day. 

Late afternoon, after the hottest part of the day has passed but before it gets dark out, is another good time to mow. 

Should you mow the lawn after watering?

No. Mowing after watering is just as bad as mowing after rain. See these other best lawn watering practices to make sure your lawn is never too wet or too dry. 

Other wet grass issues

A lawn that stays wet consistently is a problem even if you don’t mow it. Problems caused by wet grass include:

  • Pest infestations
  • Damage to grassroots
  • Soil erosion
  • Plant nutrients leaching out of the soil 

Once you’ve handled your moisture problem and your grass is dry, let Lawn Love’s local lawn care pros do the mowing for you.

Main Photo Credit: Ansh Mishra | CC BY-SA 4.0 via Wikimedia Commons

Jordan Ardoin

Jordan Ardoin is a writer and editor with a passion for sustainable, earth-friendly gardening and lawn care practices. When she isn't sharing her knowledge about lawn care and landscaping, you can find her curled up with a good book and a cat in her lap.