How often to sharpen lawn mower blades for the cleanest cut, according to experts

Sharpening at the right time can help your grass thrive.

Mowing the lawn is an essential part of your summer to-do list, but there’s another task that you should add to the lineup: sharpening your lawn mower blades. It seems like a tedious task, but sharpening your blades will not only make for a more efficient mow, but it will also help your lawn stay healthy and thriving.

However, there’s such a thing as sharpening a lawn mower blade too much. Here, we asked experts how often they recommend sharpening a lawn mower blade and how to tell it’s time to do it.

Meet Our Expert

• Mark Brokaw, go-to-market manager for turf parts at John Deere
• Ryan Duffy, division merchandise manager of power equipment at The Home Depot
• Brian Shaunfield, store manager at Lowe’s

Related: How to Winterize Your Lawn Mower in 8 Easy Steps, According to Lawn Care Specialists

Signs a Blade Needs Sharpening

The biggest sign that you need to sharpen your lawn mower blade is a simple question. “Have you ever sharpened your blade? If that answer is no, it’s most likely time to do it,” says Mark Brokaw, go-to-market manager for turf parts at John Deere.

There are other visual cues that indicate you should sharpen your lawn mower blade. The biggest one is the quality of the cut. “A sharp mower blade cuts grass cleanly, while a dull blade tears it,” says Ryan Duffy, division merchandise manager of power equipment at The Home Depot. Watch out for grass that has brown, frayed tips after mowing.

If your mower requires more effort to use or if you have to make multiple passes to get an even cut, then you probably need to sharpen your blade. “If you notice the mower vibrating more than usual, that can sometimes mean blade damage,” adds Brian Shaunfield, store manager at Lowe’s.

So how can you catch the problem early? Shaunfield recommends quickly checking your blade every few mowing sessions—especially after you’ve mowed over sticks, roots, or other debris.

How Often to Sharpen

The general recommendation is to sharpen your blades after every 20 to 25 hours of use, says Duffy—or about twice during the mowing season. “That’s typically when normal wear begins to affect cutting performance,” he says. “Following this schedule helps ensure clean, consistent cuts that promote a healthier lawn, while keeping the mower operating efficiently.”

There are a few exceptions to the rule. For example, if you ran into something that you didn’t expect while mowing, then you may have to sharpen your blade sooner, says Brokaw. Another factor: “Have you been mowing more than you usually do because of rain or ideal growing conditions?” he says. “The more you mow, the more frequently you’re going to need to sharpen.”

Your blade quality may impact timing as well. A high-quality blade will likely last longer, whereas a low-cost blade may need more frequent sharpening. Ultimately, the former may be worth the investment, as sharpening can cost you more in the long run.

Be careful not to sharpen too often, however. “Every time you sharpen your mower blade, you remove material from the blade,” says Brokaw. “If you sharpen your blade too often, the result may be having to buy a new replacement blade before you would have needed to.”

Why It’s Important

A sharp lawn mower blade will give your lawn a crisp, clean cut, but it’s more than just an aesthetic issue. When a dull blade tears the grass, it creates larger wounds that the grass has to use more energy to recover from, says Shaunfield. “At the same time, a dull blade forces the mower to work harder to achieve the same results, reducing cutting efficiency, and increasing the strain on the mower,” says Duffy.

The result is damaged grass that’s more susceptible to disease and pests and a lawn mower that probably won’t last as long.

How to Sharpen

If you want to sharpen a lawn mower blade at home, it’s a relatively straightforward process. Always make sure your mower is turned off before you start, and disconnect the spark plug wire, or remove the battery on cordless models.

After the mower has cooled, Shaunfield recommends following these instructions:

1. Tip the mower according to the manufacturer’s recommendations.
2. Mark which side of the blade faces downward before removing it so it’s reinstalled correctly.
3. Remove the blade using the appropriate socket wrench.
4. Secure the blade in a vise.
5. Sharpen each cutting edge while maintaining the original bevel rather than creating a new angle.
6. Remove the same amount of metal from both sides.
7. Check the blade balance using a blade balancer or by suspending it on a nail. If one side drops, remove a small amount from the heavier side. 
8. Reinstall the blade, tightening it to the manufacturer’s specified torque.
9. Reconnect the spark plug wire or battery and test the mower.

Read the original article on Martha Stewart