Williams suggests mowing less frequently and cutting early in the day or holding out until the sun begins to go down. “Freshly cut grass is more likely to sustain damage in the hot sun,” says Williams, “and keeping the lawn cool will cut down on those brown spots.”
During a heat wave—a period of abnormally hot weather that lasts longer than 2 days—it's recommended that you do not mow your lawn.
Typical warm-season grass height range: 1-3 inches. During periods of peak growth, expect to mow the lawn once every 5-7 days. Conversely, during times of slowest growth, you'll mow less, if at all.
Put your lawn mower on a high setting, to leave the grass around 3 inches high. Taller blades provide more shade for your lawn's root system, which keeps it cooler during hot summer days. Additionally, taller blades of grass result in deeper, stronger roots. Deep, regular watering.
Once temperatures reach 77 degrees, it becomes too hot for root growth, and root growth ceases. When temperatures reach 90 degrees, it becomes too hot for shoot growth and the grasses stop growing and begin to fall dormant, with the surface grass turning a brown hue.
Mow your cool season grass to 3 or 3.5 inches in summer, or up to 4 inches for tall fescue and perennial ryegrass. Warm season grasses should round out at about 2 to 2.5 inches.
Lawn clippings usually do not need to be bagged. Recycling lawn clippings can reduce your fertilizer needs and improve your soil. Recycling clippings to the lawn does not contribute to thatch. If you must remove clippings, they can be composted or used as mulch.
Mowing a lawn in the middle of a summer heatwave is one of the worst things you can do to it. When temperatures reach around 85 degrees, grass, like many other green plants, begins to suffer – especially cool-season grasses such as Kentucky bluegrass, perennial ryegrass, and fine fescues.
Between irrigation and natural rainfall, your grass should receive between 1 and 1.5 inches of water each week during the summer. Water deeply every other day for the best results.
Once your grass has come out of its dormant state, you may be wondering when you should start cutting it again. Generally speaking, if it is below 50 degrees Fahrenheit, it is still considered to be too cold to mow your lawn. The ideal temperatures to mow are between 50 to 80 degrees Fahrenheit.
Mower Height
A mowing height between 2.5 to 3 inches is best for most of the season, except during summer stresses when the lawn mowing height should be raised one-half inch to mow at 3 to 3.5 inches. Raising the mowing height provides more insulation from summer heat and reduces water loss from your soil.
For this reason, some people prefer to mow at 3 or 3.5 inches. For the healthiest and most sustainable approach, Michigan State University Extension says 3.5 to 4 inches is most desirable. Lawns mowed at 3.5 or 4 inches out-compete weeds, tolerate grubs and look just as good as lawns mowed at 2.5 inches.
Proper Mowing
Mow the lawn as high as possible—as high as you can comfortably tolerate. A longer lawn means more leaf blade, and this provides several benefits. More leaf blade means more photosynthesis, which results in stronger, more prolific root and shoots growth.
During really hot weather, water your vegetables at least two to three times a week. Watering the garden deeply is critical. The water must go down, down, down to encourage deep roots and get away from the hot soil surface.
Highlights. Avoid watering grass on a hot afternoon when it's 95 degrees or higher. The best time to water grass is at dawn or in the early evening. Water deeply three times a week instead of a little water daily.
SYNTHETIC TURF IS 40-70 DEGREES HOTTER THAN SURROUNDING AIR TEMPERATURES ON WARM SUNNY DAYS. On clear warm days, synthetic turf fields get superheated to temperatures from 120 to 180 degrees F. Playing on synthetic turf can melt shoes, blister hands and feet, and induce dehydration and heatstroke.
Bare or Brown Spots
Brown or bare spots are not a good sign. While they are more obvious, when you see brown spots or bare spots, your lawn is extremely stressed and some damage has already been done. Begin watering regularly.
Scotts® TurfBuilder® UltraFeed™is an excellent choice for fertilizing lawns that tend to get stressed in the summer. It holds onto nutrients until your lawn needs them, then releases them. Because of this, a single feeding can last up to 6 months.
As the heat starts to put stress on your lawn you may notice full brown blades of grass or grass with brown tips. They may have begun to curl.
Mowing every two weeks — instead of weekly — and not dousing grass with chemical herbicides and fertilizers, helps the environment and supports the health of bees, which are among the world's most important pollinators.