How Often Should Lawnmower Blades Be Sharpened?

If you’re someone who takes pride in your lawn, then you know the importance of having a well-maintained mower and one of the crucial things you need for a perfect cut is a clean and sharp blade of course. Over time, however, the blade will dull with use and needs to be sharpened, but just how often should you do this? 

If you want the best cutting performance for the least amount of blade maintenance time and effort then sharpening your blades every 25 hours is widely seen as a good guide. For homeowners with small lawns, most professionals recommend that you sharpen your lawnmower blade at least once every season as the minimum. 

In this post, I’ll talk about the different types of blades, ways to know when blades need sharpening, and how to sharpen them yourself. Let’s go!

Optimal Frequency For Sharpening Lawn Mower Blades

The frequency with which you should be sharpening your lawnmower blades will depend on several factors. That said, a good rule of thumb is to sharpen the blades at least once per mowing season as a minimum or after every 20-25 hours of use for a more healthy lawn.

Here are some of the things that will affect how often you have to get the angle grinder out.

How often do you use the mower – If you have a large yard and use your mower a lot, then you will use up that 25-hour window pretty quickly. In this case, you will probably be used to sharpening the blades every month at least.

The terrain you’re mowing – if your lawn has a lot of rocks or debris, it could cause the blade to dull quickly. Similarly, if you’re mowing on uneven ground or a sloped area, it could also result in the blade needing sharpening sooner. 

The type of grass in your lawn – grass types can also affect how often you need to sharpen your lawnmower blade. If you have thick, coarse grasses like tall fescue or St. Augustine, they can be tougher to cut and may dull the blade more quickly than softer grasses like Kentucky bluegrass. 

How long the grass is – mowing longer grass can also play a part in dulling the blade quicker. If you have to leave your grass longer between cuts due to time constraints for example, then be prepared to sharpen your blade more often.

How To Know When Blades Need Sharpening

There are several signs to look out for when it comes to identifying dull mower blades. Some of the most obvious include:

  • Visual inspection – make sure you check your blade for a damaged or dull edge every time you use the mower.
  • Uneven grass – If the grass you just mowed looks uneven or has patches that have not been cut down, it’s time to sharpen your mower blades.
  • Grass tips are torn or jagged – This is another sign that your blades are dull and in need of sharpening.
  • It takes more than one pass – If you find yourself mowing over the same spots multiple times, then it may be because your blades are dull or unevenly sharpened.

Can You Sharpen A Mower Blade Too Much?

It’s possible that after repeated sharpening, your blade may actually become dangerous to use.

Most manufacturers recommend that there should be no less than half an inch of metal between the sharpened edge and the fin (the part that angles up opposite the cutting edge).

Check the manual that came with your mower for your own specific recommendations and never continue using a blade once it has become too thin or damaged.

How To Sharpen Your Lawn Mower Blades

Sharpening your lawn mower blades can be done in two ways: by yourself or by a professional. If you want to DIY, all you need is a file or a grinder and this step-by-step guide:

  1. Remove the blade from the mower. Before you start sharpening, turn off your mower, remove the spark plug cap, and remove the blade.
  2. Inspect the blade. Look out for any damage or cracks in the blade. If there are any, then it may be time to replace it.
  3. Sharpen the blade. With a hand file or a grinder, sharpen the blade at the same angle as it came from the manufacturer. This is usually between 30-35 degrees but on some models, it could be as much as a 45-degree angled edge. Be sure to maintain an even, flat blade edge throughout the process.
  4. Balance the blade. Once you’ve sharpened the blade, check for balance. You can do this by balancing the center of the blade on a round metal bar or similar and checking to see if one side is heavier than the other. If so, file the cutting edge on that side a little more to make it lighter and test again.
  5. Reinstall the blade. Once you’re satisfied that the blade is sharp and balanced, reinstall it onto the mower.

Make sure that the bolt(s) holding the blade in place is tight enough. If you aren’t sure how tight the bolt should be, check out this article. If you aren’t sure which side of the blade goes up, you can read this article.

Check out this video if you want to see how it’s done: 


Do Different Types Of Blades Need Sharpening More?

There are five main types of lawn mower blades: straight, high-lift, low-lift, mulching, and gator. There is not much difference between them in relation to when they will likely need sharpening so follow the guideline of once per season or 20-25 hours of use as a rule of thumb.

Here’s a quick rundown of the blade types so you know what they are used for: 

Straight blades (also known as medium lift or standard mower blades) are the most common blade type and are found in both push and riding mowers. They are generally suitable for most types of mowing.

High lift blades are specialty blades used when you need to regularly cut tall (over 3″) grass. 

Low lift blades are for sandy soils and where you usually cut short grass (less than 3″).

Mulching blades (also known as multi-purpose blades) are specifically designed to suck grass up and then cut it into finer pieces before dispersing it back onto the lawn.

Gator blades are used for shredding leaves as you mow and are typically found in commercial and larger residential mowers.

If you want to learn about the various types of mower blades in more detail, this article can help you

Final Words

Sharpening your lawnmower blades regularly is essential to the upkeep of your mower and the overall health of your lawn. 

Remember to keep track of your mowing time in between blade maintenance, inspect your blades frequently, and sharpen or replace them as needed. 

With the tips provided in this post, you can keep your mower blades in tip-top shape and mowing efficiently throughout their lifetime.

Peter Toth

Hi! I'm Peter, the owner of BackyardGadget. Working around the house has always been a big part of my life. I've created this site to share my experience, and to help people choose the right tools for the job. Thank you for stopping by!

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