You could hire a full-time greenskeeper, an expert who will mow your grass two or three times a week, perfectly regulate the water your lawn gets, apply special treatments whenever needed, etc., but most homeowners do it themselves. You’ve got to know how often to mow. When you mow too infrequently, you risk cutting too much of the grass blade, which can cause the grass to turn yellow. Same with fertilizing: Lawns with too much fertilizer are prone to disease.