Summer lawn stress can be a problem come July and August. Extended periods of heat and humidity, sunshine, warm nights with no rain can add up to a heat stressed lawn. Heat stress on lawns is the how the grass responds to summer’s high temperatures and lack of water. Common problems you will see in the summer include wilting, browning, dormancy or even death.
Once temperatures get into the low 80s and above, lawns begin to struggle. Cool-season grasses, like fescue, bluegrass and rye, will have the hardest time. Warm season grasses like Zoysia, St. Augustine, Centipede, and Bermuda will fare better until the temperature reaches into the 90’s. Summer lawn stress increases susceptibility to disease, insect pests, and weeds during this period more than any other time of the year.
Warm season grasses may love these conditions, but in the northern zones, cool season grasses become stressed, wilted, and prone to disease. The heat and lack of rain call for watering, but the excessive moisture has the ability to create disease conditions. The most common reason lawns turn brown is drought stress. Common turf grasses in the United States naturally go dormant during hot, dry weather as a protective measure. When provided sufficient water, they will remain green but with little growth. However, watering still may not stop the grass stress and you will see signs of summer lawn stress. The good news is that most lawns recover fairly well and will return as fall temperatures and rain return. Here are a few simple steps can be taken to deal with summer drought and lawn stress.
Early Signs Of Summer Lawn Stress and What To Look For
1. Locate a brown patch, and pull on the grass. If it won’t pull easily from soil and is firmly rooted, it’s likely brown due to drought.
2. Push a screwdriver into soil in brown and green lawn areas. If the blade slips easily into green lawn and won’t penetrate brown, soil is dry. In rocky soil, dig a small hole to check soil moisture.
3. Look at the lawn as a whole. When drought is the culprit, brown patches appear randomly and in rough patterns. Lawn near a sprinkler head may be green, while lawn further away is brown. Grassy areas in shade remain greener when parts in full sun turn brown due to drought. Lawn in low spots will remain green while higher areas turn brown.
Learn the early signs of drought stress. Footprints that remain on grass after it’s walked on. Some grasses develop a grayish cast, while other grasses become darker hued. Grass blades may also wilt. Blades of grass will fold easily and lose “spring back”. Finally, look for brown patches and small areas of dead grass.
If You Water, Do It in the Morning
Morning is the most efficient time to water your lawn. Less is lost to evaporation and your lawn has time to dry off before nightfall. Watering in the afternoon is throwing water away to evaporation. Try to water as early in the morning as possible, just as the sun is coming up. Watering at night invites disease. Half an inch twice a week or 1 inch a week should keep your lawn refreshed
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When Your Lawn Is Stressed Out, Hold Off on Fertilizing
Stressed-out lawns aren’t growing, so fertilizing them won’t help. Instead fertilize before the hot, dry weather arrives. When your lawn is growing steadily in the spring, keep it well-fed. If you try to fertilizer in the summer, you increase the chances of burning or killing your lawn. For more tips on fertilizing your lawn see my post on when to use lawn fertilizer.
When It’s Hot and Humid, Keep an Eye Out for Brown Circles in the Lawn
If you have large, brown circles on your lawn, you could be looking at brown patch fungus. Brown patch shows up when the weather turns hot and sticky. Its circular patterns are sometimes several feet wide. While any lawn can suffer from brown patch, lawns with St. Augustine grass are particularly vulnerable.
Try Not to Walk on Your Grass
When you walk on well-watered grass, the grass blades spring back. On a dry lawn, the grass stays beaten down, and the grass itself can be damaged. Also, heavy foot traffic can lead to soil compaction, which keeps air from getting to the roots of your grass.
Keep Your Mower Blade Sharp and High
Dull mower blades shred grass, so they lose more moisture than they would with a clean cut. Also, the shredded tips turn brown, making the lawn look dull. Set your blade at the highest setting on your mower. Taller grass grows deeper roots.
Overseed in the Fall
If your lawn is prone to heat stress, you might want to over seed it with a grass that’s formulated to handle heat and drought. As an example, Scotts Turf Builder Heat-Tolerant Bluegrass seed contains Thermal Blue Kentucky bluegrass, which stays green even in scorching heat and drought. There are many varieties of Scotts Turf Builder grass seed for every region of the country.
During periods of hot, dry conditions, both cool- and warm-season grasses can go dormant as a protective measure. If grass receives sufficient moisture, growth slows and blades remain green. During times of prolonged drought without irrigation, grass will turn brown. Don’t water it unless you plan to continue watering the rest of the summer. When grass shifts out of dormancy, roots will be depleted of reserves, making your lawn susceptible to further stress. Don’t let a newly established lawns go dormant. With a limited root system, a new lawn might not survive dormancy.
It varies by region, but grass that’s completely dormant may take up to three to four weeks to turn green again. Providing more water doesn’t help your lawn at this point. Some cool-season lawns will even go dormant in the summer, looking brown and brittle until early fall. You also may have to reseed a lawn that has gone dormant, especially with cool-season grasses like rye and kentucky blue.
Lawns also turn brown during summer due to insect activity. To determine if root-munching insects are present, pull firmly on brown grass. If it slips from soil and few or no roots are present, white grubs may be to blame. Other insects eat grass blades, which causes lawn patches to appear as if they have been mowed too closely.
Insects that attack lawns during summer include white grubs, chinch bugs, sod webworms, army worms, and cranberry girdler. Check with your local extension office to learn which pests plague which grass types in your area, the best methods for insect control, and how to deal with an insect infestation.
The key to avoiding lawn stress is to maintain year-round health. Summer lawn care is about KEEPING it healthy while temperatures soar and rainfall is at a minimum. It’s also about maintaining a lawn that can withstand all the barbecues, games, parties, and running feet that summer has to offer.
Grass will tolerate the heat more easily if it is in a healthy state throughout the entire year. The cooler weather and rains of fall are only a few months away, and will help to rejuvenate the lawn. Season-long care includes proper fertilization, watering, mowing, and pest control that all help to produce a consistently healthy lawn that is best able to tolerate summer heat and other stresses. In terms of your own health, think of step one as eating right, regular exercise and good sleep to insure your best long-term health.
By Victoria Stone