The Danger of Dull Mower Blades & What to Do About It

After all the time and effort you put into mowing your lawn, the last thing you want is for your grass to look worse after it’s done. However, if you don’t keep your mower blades sharp, the final product might be a little underwhelming—think brown-tipped grass or entire chunks of sod ripped out. Ouch.

Naturally, you want to avoid this, and The ROP Shop is here to help. In this article, we’ll share why it’s important to keep your mower blades sharp, how to recognize when it’s time to sharpen your blades, and how to get it done.

THE DANGER OF DULL BLADES

When your lawnmower blades aren't sharp, you’ll wind up shredding the grass when you mow rather than slicing it. This lengthens your lawn’s healing time after each cut. During that recovery time, your grass is more susceptible to pests, drought, and heat.

If you keep cutting using dull mower blades, your lawn could eventually just give up. As a result, you'll see discolored spots where the grass has started to die, making your lawn look less like a lush carpet and more like a patchwork quilt.

Avoid this headache by paying attention when you mow. You might already be seeing red flags and just not know it.

SIGNS OF DULL MOWER BLADES

You can generally tell that your lawnmower blades have become dull by looking at your grass.

Your mower’s blade should slice cleanly through each piece of grass, providing an even cut and causing minimal damage.

Finally, take note of whether it feels like there’s something wrong with your lawnmower. Does the engine seem like it’s struggling? Has your mowing time increased? If so, don’t schedule with a mechanic just yet. Check your blades first. You might just avoid a bunch of unnecessary troubleshooting.

MOWER BLADE SHARPENING TIPS

Sharpening your mower blade

Before you start sharpening your mower blade, be sure to wear the proper safety equipment. At the very least, don a pair of work gloves and some safety goggles.

Once you’re ready to begin, remove your blade and secure it in a vise. If you’re doing this the old-fashioned way with a file, press the file firmly against the blade, matching the angle of the cutting edge, and sharpen it in a single direction. Don’t drag the file back and forth, and don't sharpen any areas aside from the cutting edges on either end. After every ten strokes, test the blade with your hand.

If you’re using a drill-powered blade sharpener, place the grinder over the blade’s edge. Be sure that the grinder’s guide (the flat piece) is against the back side of the blade and that the cutting edge is in between the two pieces of the grinder. With these sharpeners, you don’t have to worry about finding the right sharpening angle since they adjust automatically. Shift the grinder back and forth across the blade’s edge four or five times with moderate pressure. Then test the blade against your hand. ¹

How sharp should your mower blade be?

You can tell that your mower blade is sharp enough when it feels about as sharp as a butter knife and doesn't break the skin.

If you sharpen your blade too much, it will become too thin and will dull more quickly, landing you back where you started.

Re-installing your freshly sharpened mower blade

When you re-install your blade, make sure you don't install it upside down! You'll know if your mower blade is upside down because the angled side will be facing down (that is, away from the mower deck).

If you install the blade upside down, it won't cut properly, so make sure that the angled side is facing up.

Lastly, before tightening the blade down, make sure it's perfectly centered and balanced. Mowing with imbalanced blades can stress your engine and harm your mower deck. A couple of ways to know if your blades are imbalanced is if you’re experiencing a lot of vibration when you mow or if patches of grass on one side of the mower look worse than those on the other side. ²

STAY SHARP

For those interested in maintaining a healthy and well-manicured lawn, keeping lawnmower blades sharp is a necessity. Keep in mind the warning signs we discussed so that you know what to look out for and when you should sharpen your mower blades:

• Grass that’s turning white or brown at the tips
• Grass with a torn or shredded appearance
• Clumps of grass torn out of your lawn
• Lawn dying in spots
• Decreased cut quality from one side of your lawnmower to the other
• A mower that’s struggling to perform
• Increased mowing time

By properly maintaining your mower blades, you’ll be taking an important step to keep your lawn and your lawnmower happy.

But you never know what life’s going to throw your way. It’s always a good idea to keep a couple of spare blades on hand just in case. Check out our selection of lawnmower blades to stay prepared.

Is your mower struggling despite having sharp blades? Perhaps our guide to mower troubleshooting can help.

[EDITED 4/2023]