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.
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.
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.
The ideal temperatures to mow are between 50 to 80 degrees Fahrenheit. Does grass stop growing at a certain height? Once temperatures have become consistently warmer, it is a good idea to follow the one-third rule, which means to never clip off more than one-third of the grass' current height in one mowing session.
If the grass is too wet, you shouldn't mow and if it's too dry you shouldn't either. Remember, mowing is a stressful event for your lawn. If you mow when it's already under stress, such as during dry spell or drought, then it will become even more stressed. You don't like to be stressed and neither does your poor lawn.
However, when the weather is hot and generally dry, you'll be safe to mow either every 5 or 6 days. Ultimately, during the summer, you should expect to almost never wait a whole week to mow your lawn. Waiting too long to mow your lawn can overwork and damage older mowers — learn about our lawn mower repair service.
In the summer, keep both cool-season and warm-season grasses slightly taller. Cut cool-season grasses to 3 or 3 ½ inches. Mow warm-season grasses to 2 or 2 ½ inches. In summer, grass can be kept a bit higher to prevent weeds, help shade the soil line, and maintain water in the soil.
Mowing actually helps make your grass grow thicker because the tip of each blade contains hormones that suppress horizontal growth. When you cut the lawn, you remove these tips allowing the grass to spread and grow thicker near the roots.
Wear a hat wide enough to protect your face. Drink plenty of fluids to stay hydrated. Avoid high-energy activities or work outdoors, during midday heat, if possible. Check on family members, older adults and neighbors.
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. Test whether your sprinkler system is watering your lawn evenly.
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.
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.
Grass growth patterns throughout the year
Mid-summer can bring short periods of dormancy during drought conditions, but grass can also grow well if it has adequate water and sunlight. By late summer, growth starts to be restricted as temperatures drop and the light from the sun is less available.
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. Your turf should receive about 1/3 an inch of water every two days in order to maintain deeper roots, thus helping protect against drought.
Most lawns need to be watered no more than three days a week in the spring as well as in the summer and two days a week in the fall. This watering schedule is recommended under normal water supply conditions.
Grass can turn brown and go dormant when it's stressed by drought, heat, or both. It's your lawn's way of conserving energy and water, Mann explains. The grass will break dormancy and begin growing again when the temperatures and/or rainfall levels become more ideal for it.
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.
'As long as your blades are sharpened, and the grass isn't not soaking wet, mowing in the early morning dew is totally fine,' says Douglas Dedrick.
Mid-morning (between 8 and 10 a.m.) tends to be the best time of day for mowing your lawn. It allows enough time for dew to dry, resulting in strong, perky blades of grades, while avoiding the hottest periods of the day.
As a general rule your first grass cut of the year should be in early Spring. Depending on weather and temperatures at the particular time, the last week in February or the first week in March is a great time to start.
"As the outside temperature rises, your family's risk of heat stroke rises right along with it," Dr. Warmink said. "On 100-degree days, it's best to stay inside when it gets that hot. If temperatures exceed 90 degrees, stay in the shade and keep an extra eye on the kids."