How to Sharpen Your Lawn Mower Blades: An Ultimate Guide

We all know that our lawns need regular maintenance — there’s all the feeding, watering, scarifying, and aerating to consider. But actually, one of the most fundamental ways to keep your lawn healthy and flourishing is mowing. But you’ll need to know how to sharpen lawn mower blades to protect your lawn.

Cutting with blunt blades tears the grass, leaving a large wound, which leaves your grass plants susceptible to infection. So, cutting with sharp edges helps protect your grass plants while giving them a burst of energy.  

In this ultimate guide, I’ll share tips and tricks on how to sharpen lawn mower blades for yourself. 

Ready? Let’s get to it.

Introduction to lawn mower blade sharpening

Every time you mow your lawn, the cutting blades experience friction. And while grass leaves are relatively easy to cut and unlikely to cause too much resistance, your lawn mower’s cutting blades also come into contact with stones, sticks, and debris, which — over time — blunts the blades. 

So, lawn mower blade sharpening removes the dullness from the mower’s cutting blades. And this provides a sharper edge to slice through your grass.  

Consider blade sharpening an essential part of lawn mower maintenance. Do it regularly to ensure your mower cuts your grass efficiently because a dull blade will tear through the grass stem, leaving it susceptible to disease and pests.

Why is it important to sharpen your lawn mower blade?

Sharpening your lawn mower blades is important for several reasons. 

Firstly, it ensures your mower cuts grass effectively and evenly. A sharp blade makes clean cuts, minimising the wound on the grass leaf, which reduces the risk of disease or cellular damage. 

Secondly, a sharp blade will make lawn mowing more effortless and less time-consuming. Let’s face it: who doesn’t want a more leisurely life?!

Finally, a sharp blade will help improve your lawn’s overall appearance because the cut will be more consistent across the lawn’s surface. 

Signs your lawn mower blade needs sharpening

There are a few signs that indicate your lawn mower blade needs sharpening. If you notice:

• The grass has an uneven cut or appears torn — this is a sign that the blade is dull. 
• Brown tips on your grass leaves — this is an indication that the blade is not cutting the grass cleanly. 
• The mower vibrates excessively while in use — this may indicate that the blade is unbalanced and needs to be sharpened.

Tools needed for sharpening lawn mower blades

Before sharpening your lawn mower blade, you’ll need to gather a few tools. 

The tools required for sharpening lawn mower blades are:

• A socket wrench or adjustable wrench
• A blade balancer
• A metal file or bench grinder
• A pair of safety gloves and safety glasses

How to sharpen lawn mower blades — step-by-step

Follow these steps for the best results:

1. Ensure petrol mowers are completely disengaged by disconnecting the spark plug wire to ensure the mower cannot start accidentally.
2. Remove the blade from the mower deck using a socket wrench or adjustable wrench.
3. Clean the blade thoroughly with a wire brush or a scraper. Remove as much dried-on grass and mud as possible. 
4. Check the blade for cracks or damage. You’ll need to replace the blade if it’s damaged. 
5. Use a blade balancer to check if the blade is balanced. If not, use a metal file or bench grinder to remove any excess material until it is level.
6. Use a metal file or bench grinder to sharpen the blade, following the angle of the existing blade edge, and work the edge until it’s sharp.
7. Reinstall the blade onto the mower deck and reconnect the spark plug wire.

Different types of lawn mower blade sharpeners

There are several types of lawn mower blade sharpeners available on the market. The most common types are:

• Bench grinders: Bench grinders are popular for sharpening lawn mower blades. They’re easy to use and can quickly sharpen the edge to the desired angle.
• File sharpeners: File sharpeners are the manual option for sharpening lawn mower blades. This approach is remarkably affordable and easy to use but requires considerably more effort and time than electric bench grinders.
• Rotary sharpeners: Rotary sharpeners are a new type of sharpener that uses a spinning abrasive disc to sharpen the blade. They’re simple to use and quickly sharpen the blade with barely any effort.

Tips for maintaining a sharp lawn mower blade

Now your blades are sharp, it’s time to consider how to keep them from blunting too quickly. 

A few tips to keep in mind: 

1. Always check the blade for damage and balance before sharpening it. Sharpening a damaged blade could be dangerous or snap the existing metal.
2. Ensure that the blade is sharpened to the correct angle. This ensures a precise and clean cut, preventing exposure to disease and pests.  
3. Always wear safety gloves and glasses when sharpening the blade. Obviously, you can cut yourself, but your eyes are at risk from sparks or minute shards of metal, especially if you’re using an electric sharpening tool. 
4. Always clean the blades after mowing your lawn. And keep the underside of your mower free from debris to ensure it lasts longer.

Common mistakes to avoid when sharpening lawn mower blades

Here are the most common mistakes that people make when sharpening lawn mower blades. 

Firstly, failing to balance the blade before sharpening can result in an unbalanced blade. This can cause an irregular cut but may also damage your mower. 

Secondly, sharpening your blades to the incorrect angle can also result in an uneven cut, leaving you with an unattractive, choppy turf. This may also result in inadvertently cutting your grass too short, damaging your grass plants.   

Finally, always wear safety gloves and glasses, even if you’re manually sharpening your lawn mower blades. It’s always better to be safe than sorry!

Conclusion and final thoughts

Sharpening your lawn mower blade is an essential part of lawn mower maintenance. It helps to ensure that the mower cuts your grass effectively and evenly, making lawn mowing more manageable and less time-consuming. 

Following the steps outlined in this guide helps you sharpen your lawn mower blades to keep your lawn looking pristine. 

And remember: always wear safety gloves and glasses when sharpening the blade and maintain it regularly to ensure it lasts longer.

For more advice about maintaining the perfect lawn, check out our Help & Advice section, or get in touch, and we’ll be more than happy to help!

Frequently asked questions about lawn mower blade sharpening