Keeping Your Lawn Mower Blades Sharp
Published 12 November 2021
Have you ever checked how sharp your mower blade is? With a dull blade, even if you follow every mowing tip going, keeping a tidy lawn is an uphill struggle.
Here is some advice on keeping your mower blade sharp and your lawn looking even sharper.
How important is a sharp mower blade?
Think of a razor. You cannot get a clean shave with a blunt blade. In the same way, a blunt or worn mower blade leaves the lawn looking untidy and damages the grass. If you have used a lawn levelling rake to get a smooth lawn, it would be a shame for a blunt blade to spoil it.
A dull cut tears the grass instead of slicing it. Torn grass gets stressed and is more open to pests and disease. Keeping a lawn looking good takes a lot of work through the seasons, and a badly kept mower can undo it.
How do I sharpen my mower blade?
You can use a bench grinder, a rotary tool, a hand file or an angle grinder. There is also a drill attachment with a sharpening stone made for mower blades. Every make and model is different, so find the right instructions for removing your blade first.
- Some mowers let you sharpen the blade without taking it off, which saves time.
- Taking the blade off lets you do a more thorough job and avoids damaging other parts of the mower.
- Stay safe. Remove the battery pack, or disconnect the ignition wire from the spark plug, before you start. On a petrol mower, drain the fuel tank before tipping it on its side, because sharpening throws sparks.
- With the blade off, give the mower a good clean. Debris that is hard to reach is much easier to scrape away.
- Before you refit the blade, check it with a blade balancer. A blade that is out of balance can damage the motor and strain the mower.
When should I sharpen my mower blades?
It depends on the make and model of your mower, how old it is and what condition it is in, how often you mow, and the size and state of the ground you cut.
If the grass looks ragged or uneven after mowing, it is time to sharpen. A good rule is to sharpen after every 20 to 25 hours of use. For a small home mower that might be once a year; for a bigger machine in heavy use it could be every couple of months.
Mowing day is also a good time to use a lawn levelling rake to spread fertiliser or smooth out uneven patches.
What does it cost?
If you like doing jobs yourself, it is cheap to keep blades sharp, as you may already have the tools. Otherwise you will need a sharpener or drill attachment, an inexpensive one-off cost, plus a little of your time.
If you would rather a professional did it, your local garden centre or hardware shop should be able to help. It will cost more each time but saves you the job. Paying someone twice will cost about the same as buying your own sharpening tool, which then lasts for years.
Check your blades regularly to keep the lawn healthy and the mower working well. Whether you sharpen them yourself or ask a local professional, it is an easy job that keeps a level lawn looking its best.