Cutting your grass with a sharp mulching blade will result in finely cut blades of grass falling to your lawn. This in turn helps to mulch your lawn, allowing for healthier, greener grass. Most lawn mowers initially have regular cutting blades attached, which cut the grass once and then blow it out either onto the ground or into an attachment bag. Therefore, it will be necessary to first manually install the mulching blades.
Disconnect the spark plug wire (while wearing work gloves) and then lay the lawn mower down on its side. Choose a flat, even spot, preferably on concrete, where you'll have enough room to work.
Wedge a small block of wood between the mower blade and the housing so that the blade is stationary.
Remove the nut holding the blade to the mower by turning it counterclockwise with a socket wrench. Remove the washer off as well, which should slide right off. Set them aside for re-installation.
Remove the block of wood and free the blade. It should slide easily away from the mower.
Slide the mulching blade onto the lawn mower. Ensure that it is level and will rotate evenly.
Replace the washer, followed by the nut. You can either hold on to the blade with a gloved hand or you can wedge the block of wood between the blade and the housing to keep it from spinning. Turn the nut clockwise, first with your fingers then with the wrench, until completely secure.
Place the mower upright and reattach the spark plug wire.
Plug the blower shoot. This allows the mower to cut the grass several times before it falls to the ground. If your mower did not come with a plug, purchase one online or through a lawn and garden retailer.