If you are only mowing one property and depending on the size, once a year should be plenty. Cleaning and sharpening the lawn mower blades should be scheduled, at least, with the time of tune up to the mower. When grass blades don’t get a clean cut, their end become frayed. The split ends of the grass opens the door to disease and becomes weaker against other stresses. In order to tell if the blades of the lawn mower need sharpening, look for frayed ends on the tips of grass after a mowing. Keep in mind, if you go a long time without mowing and grass gets long, this could lead to split ends as well.