Keep your mower blades sharp. Sharp mower blades have several benefits. First, you will use less fuel to mow the lawn if mower blades are kept sharp. Second, your lawn will look cleaner and greener. The “whitish haze” on newly mown lawns is caused by mowers with dull blades that tear rather than cut the grass. The incomplete tears dry up and turn brown, rather than healing cleanly and staying green.