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How To Know For Sure If Your Mower Blades Are Blunt/Dull? Find Out Here!

Written by William
Last Updated on January 24, 2023

How To Know For Sure If Your Mower Blades Are Blunt/Dull? Find Out Here?

Mowing your lawn can be an uphill battle at the best of times – it’s not a chore most people think of as fun. Blunt blades can make it even more unappealing, but how do you know if your blades are indeed blunt?

When Is It Time To Replace Your Mower Blades?

Being able to identify when your lawn mower blades are dull is really important. Trying to cut grass with blades that are on their last legs can be quite ineffective and can even cause damage to your mower and lawn, which is not something you want!

Most people don’t mow their lawns very often. This might be because it’s not a task that’s required very frequently, because they’ve got someone else to do it for them, or because they just don’t want to. Whatever the reason, lack of familiarity with your lawn mower can make it difficult to know when the blades need sharpening or replacing.

If you find yourself in one of these categories and are worried about the state of your mower blades, keep reading! You’ll soon find out the tell-tale signs that your blades are getting dull.

Hints that Your Mower Blades Are Blunt

Inexperienced lawn mowers need not despair! Lawn mowers are inadvertently pretty helpful when it comes to letting you know their blades need sharpening. Keeping an eye out for these few simple signs can help you to know for sure that it’s getting to that time.

One of the first things to look out for is unevenness when you’re mowing. If you’re used to seeing seamless strips of cut grass and instead you’re getting ragged or haphazard looking sections, this is a sure-fire sign that your blades are dull. Blunt blades will also be worse at cutting all grass to the same height, so if you notice you’re having to make several passes over the same area, a dull blade could be to blame.

The quality of the cuts themselves is another hint that your mower blades might be blunt. For example, a sharp blade will slice cleanly and evenly through each blade of grass, but if on closer inspection you notice the cut tips are torn or jaggedly ripped, the likelihood is that your blades are no longer at their peak.

Browning and streakiness once you’ve mown your lawn can also mean that you’ve been mowing with blades that aren’t quite up to the task. Dull blades can damage your lawn leading to discoloration and grass deterioration which not only looks ugly, but can also lead to more long-term issues.

Routinely Checking the Blades

Another way to ensure you catch dulling early on and stop it in its tracks is to check the blades of your lawn mower routinely. Every once in a while, take some time out to inspect your mower blades to look for any signs of wear that could signal blunting or other issues.

Things like dents and nicks in the blades are good indicators that the blades might not be as sharp as they should be, and can cause damage to your lawn, so finding them soon means you can resolve them before mowing. This will in turn, preserve the quality and health of your grass.

Over time, blades can also be worn down by bits of grit or soil, so blade thinning is another issue to look out for when inspecting your lawn mower blades. A blade that’s worn too thin is liable to break if it hits a stone or uneven patch of ground, which could lead to shrapnel flying into other parts of your mower or into you!

As a general rule, lawn mower blades should be sharpened after around 25 hours of mowing time. The time it takes to each 25 hours of mowing will vary from person to person and lawn to lawn, so use your intuition, but this is a handy benchmark to keep in mind.

If you’re having trouble visualising what 25 hours of mowing time looks like or how long it might take you personally, here is some more information that might be helpful. As with all things, mower blades will also need replacing once in a while, so it’s worth keeping track of how old your blades are.

What Happens if Your Continue to Mow with Blunt Blades?

Ignoring dulling mower blades is not in your best interests or in the best interests of your garden. It might not seem like that big of a deal, but mowing with blunt blades can cause more harm to your grass than you might realise.


Unevenness in your lawn is not just an aesthetic issue. You might think that a streaky lawn is not the end of the world, but the damage goes deeper than simply having a stripe patten on your lawn.

Unevenness can lead to a whole host of issues. One such issue is that not all your grass will be cut to the right height, as mentioned above. As a rule of thumb, you should only cut your grass by 1/3 of its height. Cutting any more off than this will lead to prickly and stiff grass that’s unpleasant to walk on and less lush.

Cutting grass too short will also put it at risk of drying out, diseases, and premature browning. Take unevenness seriously when you see it and stop mowing. Once you’ve sharpened and adjusted your blades, you can then continue.

Bald or Sparse Patches

Using a blunt mower can lead you to damage your lawn by leaving sparse patches or even patches without any grass at all, as blunt blades can rip up whole plants rather than slicing through just the leaf tips. Now this will look atrocious, but that’s not the worst part.

Bald patches in lawn are weak points where weeds will thrive. Without grass to compete with, and stray weed seeds or roots that make their way into the gaps will proliferate and get stronger, potentially spreading to areas of healthier grass too.

This will mean more work and expense for you than if you had just sharpened your blades in the first place. Bald patches will also be more susceptible to disease and dehydration as there will be no grass to protect the soil.

Grass Recovery Time Increases

Just as cutting any living thing will harm it, cutting your grass technically also causes trauma. This might sound silly but when you think about it, mowing grass is an unnatural act that puts stress on the grass – after all, wild grass doesn’t get its leaves chopped off at the tips!

While mowing your lawn is necessary and will aid it’s overall health in the long-term, the act of mowing does essentially damage the plants. Cutting with a sharp blade will cause minimal trauma to the grass and will allow each grass blade to recover pretty quickly and continue growing.

Cutting grass with a dull blade however, can rip and tear it which means more stress and a longer recovery time. This means your damaged lawn will take longer to heal and continue growing which can leave you with spikey and unattractive grass in the meantime.

In a Nutshell

Hopefully, this post has given you a good idea of the signs to look for to know when your lawn mower blades are starting to get dull, as well as some more information on why it’s important to mow with sharp blades.

It might seem like a trivial thing, especially to people who don’t mow their grass very often, but using sharp mower blades can quite literally make or break your lawn. For more information on how to go about sharpening your lawn mower blades, check out this article.

There are far more benefits to mowing with sharp blades than there are inconveniences, so to make the most of your garden, it’s vital to look after it properly. The last thing you want is to accidentally kill all your grass by cutting it with a blunt mower – think of the hassle and expense of having to reseed your lawn or buy and roll out turf (no thanks!).

A lush, green, healthy lawn is such a wonderful feature to have in your garden, not only for aesthetic appeal, but also for all the many uses a lawn can offer. Garden parties, barbeques, playing football with your children and so many other activities rely on a lawn, and if you can ensure your lawn is in great shape, why wouldn’t you?

About the author
Written by William
I have always had a passion for gardening and that with a background in selling lawn mowers for the past 10 years, I have become very knowledgeable in all types of gardening tools. The site was created as a hub where I can review and write about all of the tips around gardening.
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