Sound mowing practices are important during the summer months. Kentucky bluegrass lawns should be mowed at a height of 3 to 3.5 inches during the summer months. (During cool weather in spring and fall, bluegrass lawns should be mowed at a height of 2.5 to 3 inches.) The additional leaf area during summer shades and cools the crowns of the turfgrass plants. Extremely high temperatures at crown level can kill the turfgrass.
When mowing the lawn, never remove more than one-third of the total leaf area at any one time. Accordingly, a lawn being mowed at a height of 3 inches should be cut when it reaches a height of 4.5 inches. Removing more than one-third of the leaf area weakens the turfgrass and reduces its ability to withstand additional environmental stresses. Weakened turf is also more likely to be invaded by weeds.
If possible, mow in the cool of the morning or evening. Mowing at midday may place additional stress on the turf. Also, make sure the mower blade is sharp. Dull blades tear and bruise the leaf tips.
Dormant lawns (those that have turned brown) should not be mowed. Pedestrian and mower traffic could damage the turf.