We’ve all been there – your lawn has got out of hand, but you have no time to cut it. And when you finally get a moment to bring out the mower, the heavens open!
So can you cut wet grass? What happens if you do? And how long do you need to wait after it’s stopped raining before you can mow your lawn?
We’re going to look at all these questions. And we’ll tell you everything you need to know to avoid damaging your lawn.
What’s the problem with cutting wet grass?
To begin with, let’s look at what happens when grass is cut while it’s wet. The problems affect both your lawn and your lawnmower. So what are they exactly?
Let’s start with the damage to your lawn.
Wet ground is softer, so it’s easier for heavy lawnmowers to get bogged down. That can lead to unsightly, muddy tracks across the grass. And it can mean that the tyres pull out the grass by the roots, leaving behind bare patches.
It can also compact the soil, driving out the air pockets that are needed for healthy grass. And if you don’t use a collection box, the cuttings will clump together on your lawn. That will prevent air and light getting to the grass, causing it to turn yellow.
Wet grass can also slip against the blades of your mower, preventing a clean cut. Jagged and shredded grass is vulnerable to disease and pests.
So even if the grass is longer than you’d like, delaying mowing until it’s dry will give you a healthier lawn.
Mowing your lawn while it’s wet can also damage your mower. The wet grass can put a strain on the motor, potentially causing it to overheat. Wet grass can clump together and block the mower deck too.
You’ll also find your efforts almost certainly won’t even give you a neat lawn either. That’s because wet grass will bend in the path of the mower, avoiding the blades. When it dries again, it will pop back up, giving you long straggly bits all over the place.
How do you know when grass is dry enough to cut?
We all know that rain is rarely far away in our British climate! So if there’s been a downpour, how long do you need to wait until it’s safe to mow?
The exact time will vary according to how much rain has fallen, the air temperature, the length of your grass, and your mower.
On a bright sunny day, a light shower can dry up again in as little as an hour. If it’s cool and cloudy, it will take much longer. And the moisture will hang around longer in tall grass.
Ideally, you should be able to walk on the lawn without getting wet marks on your shoes before mowing. The ground should be firm beneath your feet, so you know you’re not at risk of tearing up the soil.
Is there anything you can do to minimise the risks of mowing a damp lawn?
Finding a time in spring or autumn when the grass is completely dry can be a tall order. The good news is that you can take steps to minimise the risk of damage to your lawn when you mow.
It’s still wise to avoid mowing when the ground is very wet. But if the grass is just damp, it’s possible to get away with mowing without serious issues.
The right mower is very important here.
To start with, you want something that’s as lightweight as possible. That will avoid compacting the damp soil and lower the risk of digging ruts in the ground.
The design of the deck is important too. Decks that are tapered to help the air flow will be less likely to get clogged up with wet grass.
And good lawnmower maintenance will pay dividends. Keeping your blades nice and sharp will improve the chances of cutting the grass cleanly, even if it’s moist.
Clean your mower regularly too. If you’ve mown the lawn while it’s damp, you’re likely to have clumps of grass under the deck and on the wheels.
If at all possible, avoid your grass getting very long in the first place. The longer it is, the more time it will need to dry out after rain. And as autumn turns to winter, the chances of a long enough dry spell for that to happen become increasingly remote.
Sharpen your mower blades if necessary
Keeping your mower blades nice and sharp will give you the best possible results on damp grass.
You’ll know if your blades need to be sharpened because you’ll get sub-optimal cuts. You may find the grass is left uneven, or the edges look torn or turn brown after mowing.
But if you don’t want to wait for those things to happen, regular maintenance is the answer. Aim to sharpen your mower blades after every 25 hours of use.
If you’ve got an electric mower, make sure it’s not plugged in before you start the process. And if you have a petrol mower, drain the tank first. You’ll need to turn the mower on its side to work, and you don’t want petrol spilling everywhere.
Remove the blade and use a felt tip pen to mark its bottom. That will mean you know which way to put it back in when you’ve finished sharpening it. Give the blade a clean with a dry rag before you get started.
Next, secure it in place with a vice. You can sharpen it by hand using a file or grindstone, or with an angle grinder. If using a file, hold it at a 45-degree angle to the blade as you make each pass.
You don’t need the blade to be razor-sharp. You’re looking for about the same sharpness as a butter knife. That will usually take about 50 passes with a file.
Before you replace the blade, check that it’s still balanced. It’s easy while sharpening to take off more metal on one side than the other. That will prevent your mower from running smoothly.
Test whether that’s happened by tying some string around the centre of the blade. Then hang the blade from the string and check whether it’s level. If one end hangs lower than the other, replace it in the vice and sharpen the lower end. Check that it’s level before replacing it in your mower.
Your newly sharpened blade will give you better results in all conditions. But it will be particularly important if you find yourself with no choice but to mow damp grass.
Watch out for dew
It’s important to remember that it isn’t just rain that can make your grass wet. Dew can have the same effect.
Avoid mowing your lawn in the early morning or evening when dew is most likely to be present. If you can wait until early afternoon, you’ll give any dew from the previous evening the best chance to dry out.
How often should you mow your lawn?
Trying to find a dry day at some times of the year can be difficult! So how often do you actually need to mow your lawn?
Regular cutting while the grass is growing will help your lawn stay strong and healthy.
Exactly how often you should cut your lawn will depend on the conditions at the time. Grass needs warmth, water and light to grow. Generally speaking, it will grow faster over the summer, when the weather is warmer. But that does depend on there being sufficient rainfall.
In June or July, you may need to be mowing your lawn as often as twice a week. In spring and autumn, once a week is usually sufficient. And if the weather is cool, once every ten days to a fortnight may be fine.
There’s no need to cut your lawn at all over winter. Then, the cold weather means that the grass is essentially dormant.
Take care with the first cut of the year
The first cut of the spring is particularly important. Don’t be tempted to take your grass down too short. The green part acts as the energy store, so cutting off too much in one go can starve the grass.
A good rule of thumb is to cut off no more than a quarter of the blade in one mowing session. That will ensure the grass has enough energy to recover. If you mow regularly, you can gradually reduce the height of the grass over time.
Ready to handle the rain?
The answer to “can you cut wet grass?” is yes – as long as it’s only damp.
It’s always better to wait for it to dry out fully if you can. But if the British weather means that’s not an option, you can minimise the risks with the right mower and good blade maintenance.
Just make sure the ground isn’t too soft. Even the lightest mower will churn up the soil and grass if it’s boggy. That will leave your lawn in a far worse state than it was in when you started.
So if you can, be patient. Put your feet up until it’s dry, and congratulate yourself on doing the best thing for your lawn!