How Often Should You Sharpen Your Lawn Mower Blades?

Regularly sharpening your lawn mower blades will improve the appearance and health of your lawn. It might even make your lawn mower last longer. So how often should you sharpen your lawnmower blades? Experts’ opinions vary, but the bottom line is that most people don’t sharpen lawn mower blades nearly often enough.

How often should your mower blades be sharpened?

Alan Hayne of The Lawn Care Nut Youtube Channel sharpens his lawnmower blades every month. He believes six weeks is too far to go between sharpening. The Home Depot, on the other hand, says you only need to sharpen your lawnmower blades twice per lawnmowing season.

A man mows grass on his John Deere ride-on lawn mower.
John Deere Lawn Mower | Adlan via Unsplash

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Hayne acknowledges that other people have their own way to remember when to sharpen their lawnmower blades. He admits that part of the reason he sticks with a monthly mower maintenance schedule is that, “it’s simple and it works and it gets the job done.”

The experts at The Home Depot add that if homeowners or landscapers are mowing many hours, every week, then they will want to sharpen their lawn mower blades more than twice a season. In addition, they suggest you sharpen your blades immediately if you ever run over a rock or another obstacle that could nick your blades.

Finally, Hayne says that dull blades damage grass stalks. Because grass is harder and grows more slowly in the fall, it is especially critical that lawnmower blades are the sharpest in the fall.

How many hours of mowing will your lawnmower blades last between sharpenings?

How often you need to sharpen your lawnmower blades depends entirely on how much you use your lawnmower. If you have a huge lawn that you mow twice a week, your blades will dull more quickly. The Home Depot suggests that you sharpen your lawnmower blades once for every 25 hours of use.

Orange lawn mower parked on a hill with a road and town in the background.
SCAG Lawn Mower | Elias Null via Unsplash

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According to Home Depot’s logic, if you use your lawnmower for five hours every Saturday, you can go five weeks before its blades need sharpening. But what if you only run it for one hour a week? Can you mow for 25 weeks before sharpening your blades? Not necessarily, sitting for long periods of time can also rust your mower and dull your blades.

You can always inspect your mower blades to see if they appear worn. Look for either rounded cutting edges or small chips missing from their cutting edges. Hayne admits that some folks, including the experts at The Home Depot, feel “butter knife sharp” is sharp enough for lawn mower blades. But Hayne prefers to keep his blades “razor-sharp.”

In addition to inspecting your lawnmower blades themselves, you can also inspect your lawn to see if your blades need sharpening.

Does yellow grass mean you need to sharpen your lawnmower blades?

According to lawn expert Alan Hayne, a yellow tint to your lawn can signal dull mower blades. A properly sharpened blade will slice a grass stem cleanly, leaving its end neat and its entire length bright green. But a dull blade will hack through the grass, leaving its ends frayed. Those ends will quickly yellow.

Detail photo of yellow grass caused by dull lawn mower blades.
Yellow lawn | Engin Akyurt via Unsplash

Ragged, frayed stem ends make for sickly grass plants. When grass is hacked up like this, it is susceptible to picking up diseases and even dying. Take a look at the ends of your grass blades: if they are frayed or even yellowing, it is past time to sharpen your lawnmower blades.

Next, find out how to sharpen your lawnmower blades.

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