A lawn with a brown hue and shredded-appearing individual grass blade may indicate that your lawn mower blade is dull and no longer cutting your grass effectively. To prevent disease and fungus from affecting your lawn, you'll need to replace the push mower's blade. Do this at least once a year unless you run over sticks and stones frequently. Then it should be done two to three times per year.
Grasp the spark plug wire and pull to remove it from the spark plug.
Lay the lawn mower down on either side so that you can access the blade underneath.
Grasp the blade with a gloved hand and place your adjustable wrench on the bolt that holds the blade to the engine shaft.
Turn the bolt counterclockwise to loosen it. Unscrew it all the way and set it aside.
Remove the old lawn mower blade and discard. Position the new lawn mower blade on the lawn mower in the same orientation as the old blade.
Screw the bolt back in. Turn it clockwise with your wrench until it is tight.
Set the mower back upright. Push the spark plug wire back on to the spark plug.