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How to Sharpen Your Lawn Mower Blades on Your Own to Save Time And Money: Pro Landscapers Weigh In

Plus, experts reveal how dull blades can actually ruin your lawn

“I can’t wait to mow the lawn,” said nobody, ever. It’s hardly a chore any of us look forward to doing, but the end result of a gorgeous lawn and the enticing scent of fresh cut grass makes it worth it. Until of course, you finally pull the machine out of your garage and find that it is just not cutting it, literally. The likely culprit? A set of dull lawn mower blades. The good news? You don’t need to call in a pricey pro to do it for you. Here, our tutorial on how to sharpen lawn mower blades, including landscaping experts’ tricks to make sure yours stay clean, honed and ready to keep your lawn looking immaculate.

Why do lawn mower blades get dull?

You may be wondering: all your mower does it clip down flimsy blades of grass, how could the blades ever possibly become dull from that?

“Mower blades don’t just come into contact with grass — although over time, even that would eventually dull the blade; friction is friction, even if it’s a leaf,” explains landscaper Marco Picano of Picano Landscaping. “But the blades do come into contact with harder debris in your yard such as twigs and stones, and those can quickly result in small nicks along the edge of the blades.”

A good way to prevent that extra wear and tear is, of course, to inspect your lawn before mowing and pick up and remove any sticks, bark, stones or other items you find. Bonus: Pre-inspecting your lawn can also be a good practice to ensure you don’t mow over any nests — whether from rabbits that like to hide their newborns in tall grass or ground wasps, which can pack quite a sting if you accidentally mow over their hive. (Click through to learn how to repel wasps.)

Related: The Best Time to Water Grass + The Simple Signs It Needs More

How to tell if your lawn mower blades need sharpening

How to sharpen lawn mower blades: Lawn mower shortly after use from below
Savany/Getty

This is an easy one, says Scott McLeod, owner of McLeod Landscaping Inc. “Just look at the tops of the grass after you’ve mowed — if the blades look neatly sheared off at the top, your blades are fine. If they looked ragged or shredded, that’s a sign your blades are in need of some TLC.”

Why does it matter? If grass blades aren’t cut cleanly, they are more susceptible to disease, explains McLeod. “Grass that has been shredded by a dull mower will also develop a brownish, dead-looking color to it that can ruin the appearance of your whole lawn.”

The good news? Unless your yard is a minefield of blade-damaging debris or you have a particularly huge lawn, you typically will only have to sharpen your mower blades twice a season — usually at the start, then midway through.

“You can clean them at the end of the season, too, but this can result in extra work if the blades wind up getting dirty or rusty in storage over the colder months,” says McLeod. “It’s generally more efficient to do so in the spring.”

So if your blades do need sharpening, here is how to get started …

How to sharpen your lawn mower blades in 2 steps

1. Safety first

First and foremost, you should start by making sure the mower is empty of gas, then pull the wire that attaches the spark plug to the mower, says Chris Ramos of Blain’s Farm & Fleet, which sells and repairs mowers. “This ensures the mower won’t suddenly start on its own while you’re working on it, and is standard practice for people who do mower repairs,” she says.

Luckily, removing the spark plug wire is extremely easy to do — this YouTube video from Briggs & Stratton shows how around the 40-second mark:

If you’re having trouble locating the spark plug wire on your particular mower, you can always search YouTube using the specific brand of your unit and the phrase “spark plug replacement.” You don’t need to actually replace the plug for this project — just pulling the wire is fine — but the video will show you where the plug and wire are located.

2. Sharpen the lawn mower blades

Now that you’ve ensured your mower won’t start on you accidentally, you can turn it over and remove the blades.

“Start by putting on a pair of thick gloves and placing a block of wood under the blade to prevent it from turning,” says Picano. “Next, use a wrench or socket to untwist the bolt holding the blade in place and gently pull it off.”

Once the blade is loose, you’ll need your sharpening tool — you can use a bench grinder if you have one, but a metal file will also do the trick just as well. If you don’t already own a metal file, you can find them at any home improvement store, or grab one of these: WORKPRO W051003 8 In. Half Round File or Hyper Tough Steel File.

“Run the file up and down the blade vertically, from the interior outwards, following the original angle of the blade,” says Picano, adding that it’s best to use a clamp or vise to hold the blade steady while doing this. “It should take about 10-15 minutes per blade.”

To see a demonstration of this, check out this YouTube video from Flannel Guy DIY :

When you’re done, wipe the blade clean, replace it on the mower with its bolt, reattach the spark plug wire and you’re good to go!

How to keep your blades sharper for longer

It can help to occasionally wipe your mower blades clean using a rag dampened in soapy water. Once you’ve removed any stuck-on debris, dry it completely, then apply a light layer of oil —mineral works best— which will help prevent rust and other corrosion from prematurely dulling the blade’s edge.


For more on sharpening tools, click through the links below!

How to Sharpen Scissors So They’re as Good as New — Genius Hacks Make It Easy

Life Hacks Alert! Sharpen Dull Knives in Seconds With This Common Household Item

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