Last Updated on November 3, 2020

Which Side of The Lawn Mower Blade is Up

In order to make sure your lawn mower is cutting the grass properly, you’ll need to keep your blades sharp, and possibly replace them – and make sure you have them installed correctly.

Mower blades feature a cutting edge at both ends so, it is very common for people to install them upside down.

If you install them upside down, you can do some major damage to your grass and maybe even your mower.  You’ll be “cutting” with the dull side of the blade which will rip the grass vs. cut it.

How To Know If Your Mower Blade Is Upside Down

  • Examine the blade – The majority of new blades will have etched wording or a stamp directly on the blade that should instruct you on which side ought to face the ground when it’s installed. Look for the words “This Side Down” or “Toward Grass” on the blade
  • Locate the cutting edge – Blades will have two cutting edges. One edge is dull and looks like the blade has a bend. The dull edge should be pointed back towards the mower deck (the rust or corrosion resistant part of the mower that protects a user (and the engine) from the blade itself and any debris that shoots off from the blade). The cutting edge is opposite the trailing edge and is usually sharpened to a point.

Check To Make Sure It’s Installed Correctly

Hold the deck firmly with one hand and the blade in the other hand.

Use your hand to pull steadily. If you feel a rocking movement in the blade, examine it to make certain that is correctly attached to the shaft, and then tighten up the bolt that secures it using a socket wrench.

Once you’re certain that the blade is on tightly and correctly you can then tilt your mower back to its upright position.

Tips for Mulching Blades

Mulching blades are a little different from standard lawnmower blades.

A mulching blade can have either a bend or a fin that is cut right into the back part of the blade. The fin will cause a partial vacuum inside the mower deck which will cause the grass clippings to swirl around underneath the deck so the blade will cut them a few times before they hit the ground.

The tinier pieces of lawn clippings will break down easier than the larger clippings, and that means a natural fertilizer which is nitrogen-rich for your yard.

  • Look for a model number or wording. Examine both sides of the blade and look for a model number printed on the underside or the word ‘bottom’ which might be stamped on it. Regardless of whether its a number or a word, the side where it’s printed needs to be facing the ground after installation
  • Check out the mulching blade’s shape. One part of the blade should be bent upward slightly. The bend on some brands is small, but they’ll have metal flaps cut into the blade’s back which will bend upward. Either the flap points or the slight bend protrusion needs to be facing the mowing deck after installation
  • Check the bevel. Finally, check out the part called the bevel which is located on the mulching blade’s cutting edge. The bevel is the part that cuts. It should be on the top part of the blade or the side that will be facing away from the ground whenever the lawnmower is in its upright cutting position

Here are a few of my favorite mulching blades on Amazon:

Bestseller No. 1
Bestseller No. 2
On SaleBestseller No. 3
Rotary Copperhead Mulching Mower Blades Fit John Deere Models D100 LA100 Replaces OEM GX22151 GY20850 For 42 Inch Deck (pack of 2)
Rotary replacement lawn mower blades.; Fits certain John Deere lawn mowers.; Fits OEM: AM137328, AM141033, GX22151, GY20850.

Safety First!

If you’re examining a blade already mounted on your lawn mower, make sure to drain your gas tank and disconnect any spark plug wires before tipping your mower on its side.

That way, you’ll avoid any accidental starts or any fuel spills.

If you have a battery powered lawn mower, make sure you remove the battery first.

If you’ve changed the blades, made sure the blades are on the right way and your still not getting a good cut, it may be time for a new mower.

But from my experience, changing or sharpening the blades on a mower that runs well will bring new life to it!

Author: Matt Hagens

Matt Hagens

Hi, I’m Matt the owner of Obsessed Lawn. I love to be outside working on my lawn, planning my next project. I created this website to help people like you find the best products for yard care and great advice. Learn more about me and find me on Facebook.