Mowing at the same height all year long is convenient, but may not be in the best interest of your lawn. A shorter-mown lawn is usually denser and more aesthetically appealing, but is more susceptible to stress. Grasses maintained at a taller cut will have deeper root systems, and are able to handle summer drought better than short-mown turf. A good rule of thumb is to never remove more than 1/3 of the leaf tissue at any single mowing, and raise your mowing height during periods of summer stress. When weather improves and you would like to lower the height of cut, increase the frequency of mowing and slowly lower the height over several weeks to avoid scalping.