When mowing the lawn is on your weekend to-do list, there are few things worse than unexpected rain. You may even want to think twice about checking this task off before the lawn has a chance to dry.
Cutting wet grass is far from ideal. Not only is using a lawn mower on wet turf inefficient but it can also be downright dangerous. Unfortunately, many homeowners don’t realize their mistake until they’ve already gone over a few sections of lawn.
I highly suggest giving your lawn time to dry before moving forward with the day’s landscaping chores, and I’ll explain why in the rest of this article. I’ve also included some expert tips and tricks for mowing a wet lawn as safely as possible if waiting for the grass to dry just isn’t an option.
Mowing Wet Grass
While cutting wet grass might seem harmless, it’s actually one of the worst things you can do for your lawn. And the wetter the grass the more likely serious damage will be done.
There is a bit of wiggle room when it comes to mowing grass that is barely damp from morning dew or intermittent rainfall. However, you’ll always be better off waiting for the turf to dry before starting your lawn mower.
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When Is Grass Too Wet To Mow
In a perfect world, you should delay mowing when there is any obvious moisture on the grass. But that extreme stance isn’t always realistic, especially for those of us with busy schedules. If you can’t wait, it’s generally okay to mow when the grass is slightly damp — e.g., from light morning dew or a brief drizzle.
You should never mow when the soil beneath your lawn is noticeably wet. Even slightly damp soil can cause serious problems for a lawn mower. You’re also very likely to do damage to the grass itself by mowing over wet soil.
Cutting Grass With Morning Dew
Morning dew is no different than water from rain or irrigation. For the health of your lawn, you should wait to mow until later in the morning when the dew has completely dried.
In a pinch, you can mow turf grass that has a very sparse layer of dew on it. But I don’t recommend making this a regular practice.
Mowing Lawns After Rainfall
You should wait to mow wet grass until the lawn is completely dry especially if your area has been subject to extremely heavy or prolonged rainfall. This is because the ground beneath your lawn is likely to be saturated, and the foot or mower imprints caused by moving around on soggy soil can cause damage to lawn roots and ruts in the soil.
In the case of light rain – which is similar to morning dew – this usually only takes a few hours to dry out. However, before getting out your lawn mower, I recommend you check that the soil is dry too.
Reasons to Avoid Cutting Wet Grass
As a general rule of thumb, my advice is that you should avoid mowing wet grass whenever possible. So let me explain in more detail why cutting damp grass is an issue in the first place.
There are actually several reasons why mowing a wet lawn is not recommended. It can damage the grass, disturb the topsoil, and put unnecessary wear and tear on your mower. Not to mention that mowing a wet, slippery lawn is far more dangerous than cutting a dry one.
Wet Grass Cuts Uneven
Something you’ll notice right away if you decide to mow wet grass is that the results leave much to be desired. While superficial, this is enough to convince many people that it’s best to wait for things to dry out!
When turf grass is damp, it gets weighed down. It also tends to clump together. Both of these factors make it difficult for mower blades to create an even cut.
You may notice small patches of grass are completely missing after mowing a wet lawn. This usually happens when the soil is so soggy that the mower blades pull the grass straight out of the ground with little resistance.
Clippings Clogging Your Mower
When wet grass clippings stick together, they create a real mess. Unfortunately, there’s a very good chance at least some of this mess will end up inside your lawn mower.
Wet grass clippings can stick to your mower’s wheels, making it hard to push and steer. If enough grass builds up inside the axis, the wheel could become completely locked.
Another common issue is grass clippings clogging the mower blade. Not only will this impact how well your lawn mower cuts the remaining grass but it can also weigh down the motor causing lasting damage to the machine.
Wheel Ruts or Tracks in Lawn
Pushing or driving a lawn mower over damp soil can do serious, long-term damage to the ground. One of the most likely consequences of mowing a wet lawn is leaving behind ruts from the mower’s wheels.
Particularly deep ruts can cause drainage issues and give your lawn an uneven appearance. However, even relatively shallow ruts can harm grassroots below the soil’s surface (I cover this in more depth below).
Difficult to Clean Grass Clipping
It’s good practice to clean your lawn mower after every use. If you cut wet grass, however, this relatively simple chore becomes a real hassle.
If you neglect to clean wet grass clippings stuck to your mower, the mess can become a breeding ground for slime mold and other fungi. Wet grass stuck to metal — e.g., mower blades — can also encourage rust formation.
Note that wet clippings are more likely to leave behind grass stains. Be sure to treat stains left behind on apparel, shoes, outdoor furniture, walkways, and similar surfaces as soon as possible.
Fungal Disease Loves Wet Grass Clippings
In my opinion, the risk of fungal disease is one of the biggest reasons not to mow even slightly damp grass. Wet grass clippings are an ideal place for fungi to reproduce. You can easily spread fungal spores from one section of your lawn to another using damp mower blades.
Remember: freshly cut grass is extremely susceptible to diseases of all kinds. The last thing you want to do is increase the chance of disease exposure immediately after (or even while) you mow.
Compact Soil and Damage Lawn Roots
I mentioned above that mowing over damp soil can create visible tracks in your lawn. But I also want to explain how damage can be done even if no noticeable ruts are left behind.
Compacted soil is a common problem that occurs when air pockets have been pressed out of the topsoil. Compaction can occur without any visible signs on the soil’s surface.
Plant roots need air pockets to access oxygen and other key nutrients. Compacted soil is also harder for roots to penetrate. This leaves your grass more vulnerable to drought, extreme temperatures, and other stressors.
When the soil is damp and soft, it is unable to hold its shape under the weight of a lawn mower. Even light foot traffic can cause compaction if the soil is wet enough.
Personal Risks of Mowing Wet Grass
Adhering to your schedule of how often you should mow your grass is a routine part of owning a lawn. So much so that it’s easy to forget you’re operating a piece of heavy machinery fitted with rapidly spinning and extremely sharp blades.
Even if you don’t get hurt while mowing wet grass, operating a lawn mower is hard enough without slipping and sliding or worrying about electrical hazards. It just doesn’t make sense to take the chance when there are so many other reasons not to mow the lawn when it’s wet.
Slipping and Falling
I’m sure we can all remember a time when we slipped and fell while running or playing on wet grass. It’s safe to say that it’s much harder to find your footing on a slick, damp lawn than it is on a dry one.
The risk of falling might not be at the forefront of your mind when getting ready to mow the lawn. However, it’s a very real possibility that can turn ugly surprisingly fast.
Electric Mowers Can Shock When Wet
Electric mowers have long been ‘on trend’ in the world of home lawn care. However, they pose a unique risk when it comes to mowing wet grass.
While the risk of electrical shock is low when using a properly functioning lawn mower, it does exist.
There’s also always a chance that your mower is not working as it should. Broken or eroded pieces of equipment can expose live wires. If water comes into contact with such wires, the mower could be permanently damaged or worse.
There is also the issue of the lawn mower getting wet and this in itself leads to corrosion or the ceasing of moving parts.
Extension Cord Hidden Under Clippings
Personally, I don’t use a corded lawn mower. But I have used a corded weed trimmer. So I know how easy it is to get tangled up in or completely lose track of a power cord among grass clippings and debris.
One of the worst-case scenarios when cutting wet grass with this type of lawn mower is the potential to run over a hidden extension cord. The safety risks go up exponentially when you consider the added danger of mixing water and electricity.
Best Approach to Mowing Wet Grass
If you’re caught in a pinch and must mow damp grass, there are a few precautions Purdue University advises taking to do so as safely as possible. Following these steps, plus some of my own will help produce the best results when cutting wet grass.
Use A Lightweight Gas Mower
I recommend using a lightweight lawn mower when cutting wet grass. It will be less likely to damage the turf or compact the soil underneath as you work.
Also, using a gas-powered mower may be slightly safer in wet conditions than an electric one. Keep in mind, however, that even gas-powered equipment can be damaged by excess moisture.
Use a Very Sharp Blade
One of the biggest reasons to avoid mowing a wet lawn is that the grass is harder to cut. Using a very sharp mower blade will produce better results by actually cutting the grass instead of just pushing it down. However, even a sharp blade won’t produce perfect results on wet grass.
Set Deck to Cut Grass Long
Mow your lawn at the highest recommended setting to minimize damage caused by cutting wet grass. This will also limit how much the grass is weighed down by the blades during mowing and create a more even cut.
Keep in mind that each type of grass has an ideal mowing height. I suggest looking up the recommended height range for your lawn’s specific turf variety and aiming for the upper end when the grass is damp.
No Lawn Stripes
Lawn striping is a sort of optical illusion that many homeowners take great pride in creating. While lawn striping is aesthetically pleasing, I don’t recommend attempting it on wet turf.
When conditions are damp, striping the grass with a roller attachment will place extra stress on your lawn. Instead, save your lawn stripe patterns for days when the grass is 100% dry.
Use A Bagger or Side Discharge
Funnel grass clippings away from the mowing area using a side discharge attachment. Alternately, you can attach a bagger to your lawn mower to tidily and conveniently keep wet, clumpy clippings off of your lawn.
