Your mower blade should be set at a minimum cutting height of three inches. Taller is even better. Anything less and you are cutting off too much of the grass’s light-gathering blade, which helps it produce food for itself, much like a tree does. Mowing properly will promote thickening and better lawn color even during dry periods. A thick, tall mowed lawn will discourage weeds and crabgrass from germination by blocking the sunlight where weed seeds lie. Your pre-emergent crabgrass control will also be better protected from sunlight, which breaks it down more quickly. Scalping your lawn even once greatly increases the chances of these weeds germinating. Also, excess clippings should be raked so they don’t block the sunlight. When fall arrives, you should then gradually lower your mower blade to one and a half inches. The purpose for this is that you don’t want to have long turf when the snow begins to pile up as it increases the likelihood of snow mold fungus