A mulch plug covers up the exit port on a lawnmower to force the grass downward to the ground. This cuts up the grass into a mulch. Grass mulch is a good way to protect your lawn and helps keep the lawn hydrated during hot months. Many lawnmowers have a built-in mulch pug that automatically comes down when you remove the exit port on the mower deck. If you do not have one and you plan to mulch regularly, invest in a mulch plug designed for your lawnmower. If you mulch infrequently, you can make do with a temporary mulch plug.
Cut a piece of thick cardboard from the flap of a cardboard box to match the size of the exit port on the lawn mower. Use a pair of scissors or a utility knife for this.
Hold the piece of cardboard over the hole on the mower deck with one hand. If possible, have a friend hold it for you.
Tape the cover to the mower deck with duct tape. Place the tape on the top side, right side and left side of the mower deck. Do not place duct tape on the bottom. Position the tape so it rests half way on the mower deck and half way on the cardboard.