How to Sharpen Mulching Lawn Mower Blades?

Does your lawn have a brown cast that makes the whole yard look unattractive and displeasing?

How to Sharpen Mulching Lawn Mower Blades

Well, that usually happens when your lawnmower blades are not sharp enough. After using a mulching lawnmower that has a dull blade, your yard after two to three days might not look good enough.

It is because it does not precisely cut your grass. Moreover, dull blades can be very traumatic for grasses because it tears them and does not cut them.

So, to obtain cleaner cuts and prevent your lawn from undergoing a traumatic situation, you have to sharpen up your mulching lawn mower blades.

How can you achieve this? Our detailed guide will help you from the beginning to the end. In this way, you will achieve a healthy and clean lawn.

What tools and things will you be needing? Let’s look at it below:

Tools That You Will Require:

Welding Gloves:

You need these pairs of gloves to safeguard your hands while you are sharpening your mulch blade.

Gasoline Container:

You can buy a spare gasoline container from any nearest store. You need this extra container to empty your lawn mower’s gasoline tank.

Color Spray:

You will need a color spray to mark the top of the blade’s surface. This will make your reinstalling easier.

Wood Block:

You will need a two-inch by four-inch block of wood but go for that one that has thicker edges. This wooden block will be placed between the mowing deck and the mulching blade.


You might need this to hold your mulching blade while you unscrew all the nuts. It will be a lot safer because the clamp will be holding your blade instead of your hand.


This mechanical apparatus will secure your mulching blade.

Metal File:

You need a metal file to sharpen your entire blade.


Since the nuts are quite tightly secured, you will need a wrench that will help you loosen the nuts.


This tool is optional. After you loosen up the nuts, the socket will easily remove the nuts.

It is crucial to remember that a mulching lawnmower blade, whether it is dull or sharp, can easily pierce through your hand. Therefore, wear protective gear and do it carefully.

Since you know what tools you will need and for which purposes, let’s begin to sharpen the mulching lawnmower blades.

A Step-by-Step Guide:

Step by Step Guide to Sharpen Mulching Lawn Mower Blades

Wear your gloves and follow these steps along!

1. Pull-out the Spark Plug Wire

To prevent yourself from a horrendous accident while working on a lawnmower, the first step we will do is remove the spark plug wire.

You will typically find this plug on the engine’s front; plus, its location is quite easy to spot. Once you locate the plug, pull it out by hand. Avoid using tools because your plug wire is prone to damage.

2. Empty the Mower’s Tank

Now, you need to empty out the mower’s gasoline tank into a gasoline container. This process will prevent gasoline leakage on the ground.

Moreover, several mowers contain a drainpipe for draining. You only have to unscrew the valve counterclockwise to drain.

However, if you find no drain on your mower, you will have to tip the lawnmower to drain its tank.

You can skip Step Two if you don’t want to drain out your mower’s gasoline tank.

3. Tilt Your Lawn Mower to Remove the Mulching Blade

If you tilt your lawnmower wrongly, it can cause oil or gas leakage; thus, you have to replace the entire thing. You don’t want that, of course!

Tilt your mower in a way that the carb side is up. In this way, the oil will not drain into it, and the gas will not leak. Moreover, you can tip your mower backward as well.

You can now easily access the mulching blade to remove it for sharpening.

4. Place a Wooden Block

Between your mowing deck and mulching blade, place the wooden block to prevent your blade from turning while you are loosening it.

5. Spray Paint Your Blade’s Surface

Use spray paint to create a small mark on the blade’s surface so you can distinguish the blade’s top and bottom. In this way, you can reinstall the sharpened blade easily.

6. Loosen All the Blade’s Holding Nuts

Get your driver and socket in hand because now you have to loosen all the blades holding nuts. The nuts are no bigger than ⅝-inch; therefore, you need a socket and a driver.

While you are unscrewing, make sure that the blade is not moving at all. Use the clamp to hold the blade tightly.

7. Place Your Mulching Blade in a Vise

Once you remove your mulching blade, position it in a vise in such a way that the vise is tight on the blade’s center portion. The sharp cutting edges will be pointing upwards.

8. Time to Sharp the Blade!

Now, pick up your metal file. Hold it at the same angle as your mulching blade’s cutting edge, and you have to push the metal file towards the blade’s edge.

File the cutting edge’s straight portion in one go until that portion becomes razor-sharp.

9. File the Curved Blades

You need a narrower file to sharpen your blade’s curved portions. You have to switch to a thin file because it will help you sharpen those curved edges more easily, and it gets between the edges effortlessly than the wider file.

Continue to file the blade’s curved portion until it becomes sharp.

10. Test the Blade’s Sharpness by Hanging

The mower’s mulching blade has a hole in the center. All you have to do is hang your now sharpened blade from the center onto the small nail to check if the blade hangs evenly.

If it does, proceed to the next step. If one side is heavier than the other side, you need to file the heavier side again until the balance becomes even.

11. Place the Blade Back

Time to put the mulching blade back onto the mower. Tighten all the nuts. Use a clamp to hold the sharpened blade to prevent yourself from any injuries.


You have reached the end of our guide. I hope you find it informative.

If you think of replacing the mulching blade with a newer one, you better switch to the idea of sharpening it more often before you mow the lawn. Furthermore, it will increase the blade’s longevity and will help you save a lot of dollars.

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