How to Sharpen Mulching Blades


Maintaining sharp mulching blades on your lawn mower is important for the overall health of your lawn. Dull blades tear at the blades of grass, causing them to turn brown and making your yard unattractive. Mulching blades differ from regular lawn mower blades in that they are curved. This design allows the blades to chop the grass clippings more finely and reduce a build-up of grass clippings on your lawn.

Disassembling the Blade

Step 1

Place a drop cloth down to protect the area from spills. The garage floor is a good place to perform this task.

Step 2

Remove the grass catcher from the lawn mower. Brush off any grass clippings around the opening.

Step 3

Disconnect the spark plug wire from the spark plug. This assures the mower will not accidentally start up while you remove the blade.

Step 4

Plug the gas tank: Remove the gas cap and cover the opening with a small piece of heavy-duty plastic. Screw the gas cap on again over the plastic to create a seal.

Step 5

Turn the mower on its side. Place a small piece of 2 x 4 lumber between the blade and the mower's deck to prevent the blade from moving while you remove it.

Step 6

Loosen the nut holding the mulching blade in place with a socket wrench. Remove the mulching blade from the lawn mower.

Sharpening the Blade

Step 1

Clean the mulching blade with steel wool to remove any rust build-up.

Step 2

Sharpen the blade with a steel file or grinding tool. Follow the existing curves and angles of the blade and slowly create a new, smooth edge. Remove any pits in the blade.

Step 3

Balance the blade. Support the mulching blade, in the middle, by hanging it on a nail or holding it between your thumb and middle finger. If the blade does not balance, remove the excess weight, a little at a time, from the heavy side with the file or grinder.

Step 4

Clean the underside of the mower deck with a putty knife to remove any built-up grass clippings.

Step 5

Place the blade back on the mower and secure the nut in place with the socket wrench.

Tips and Warnings

  • Wear protective gloves when handling the mower blade and protective eye wear when sharpening the blade.

Things You'll Need

  • Drop cloth
  • Plastic
  • Piece of 2 x 4 lumber
  • Socket wrench
  • Metal file or grinder
  • Putty knife


  • YouTube: How to Replace or Sharpen a Lawn Mower Blade
  • Weekend Gardener: How to Sharpen Lawn Mower Blades

Who Can Help

  • Colorado State University: Lawn Mower Maintenance
Keywords: sharpening mulching blades, sharpening mower blades, lawn mower maintenance

About this Author

Sophia Darby is a former professional hairstylist who has spent the last six years writing hair-related articles for both online and print publications. Her work has appeared in Celebrity Hairstyles Magazine, as well as multiple websites.