Summer lawn care: Has your grass turned brown?

Has your lawn turned from green to brown? No need to worry, your grass has probably just gone dormant from the summer heat.

Regardless of when the dog days of summer arrive, your lawn may turn brown and appear “burnt” or “burned out” in spots. Assuming your lawn is free of disease, there’s no need to panic, it’s just the grass responding to the heat.

Why grass turns brown (looks “burnt”) in summer

In the upper south, parts of the midwest, Pacific Northwest, or the northeast U.S., your lawn is most likely planted with cool-season grasses like Kentucky bluegrass, perennial ryegrass, fine fescue or tall fescue. Cool-season grasses look great in spring and fall because they thrive when daytime temperatures are in the 60-75 degree range and rainfall is normal. But during the dog days of summer in July and August, they become dormant until temperatures return to cooler conditions sometime in September.

Dormancy is a survival mechanism for cool season grasses. When daytime temps consistently reach 90+, the grass re-allocates its resources to the roots and crown instead of the blades. Very little growth occurs and the grass turns brown, giving homeowners the impression their lawn is dead or diseased. That’s why in August your lawn usually needs to be cut less often.

[su_quote cite=”LSU Ag Center” url=”https://www.lsuagcenter.com/topics/lawn_garden/home_gardening/lawn/drought-dormant-lawns”]Grasses have the ability to go dormant for differing lengths of time depending on their genetics, rooting and overall health. The spectrum of grass stress runs from reduced growth or some discoloration at moderately dry levels; to drier conditions where recovery is possible but plants brown out (fire up) and weaken; to deep dormancy where we see damage or death. Dormancy is simply a state of reduced metabolism and water usage where the plant focuses resources on the roots and survival. The grass will turn mostly brown and is considered unsightly — but not dead.[/su_quote]

Does fescue turn brown in winter?

You’ve probably noticed that your lawn also turns brown in the winter, but it takes on a somewhat different brown than what you see in summer. Winter dormant lawns are consistently brown throughout, with a straw-like tone. In summer dormancy, the lawn may appear spotty or patchy – some brown here, some green over there. Unless you water your lawn deeply every week, there is little you can do during dormancy to get your lawn green again. But there are some things you can do which may cause a great deal of damage.

How to protect a dormant lawn so it greens up quickly when the weather cools

Don’t mow a brown, dormant lawn on your regular schedule

When your grass has turned brown, don’t mow your lawn just because it’s Friday night and that’s when you always do it. In fact, you should never mow your lawn if it’s less than three inches tall, whether it’s green or brown. During dormancy, it’s beneficial to let the lawn grow a little higher than usual, as the longer grass blades provide more shade for the roots and help to keep what little moisture there is in the soil from evaporating. The shading may also keep lingering weed seeds from germinating.

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Don’t fertilize a dormant brown lawn

Do not fertilize your lawn during a dormant or hot period. It’s not a nutrients problem, so no amount of lawn fertilizer in the world will help it. The fertilizer can’t be taken up by the water-starved roots, and the nitrogen-heavy fertilizer left to lay on your lawn may actually “burn” it, leaving you with bigger problems to fix in the fall.

Keep your brown lawn from dehydrating

The key to keeping your summer lawn from going dormant to dead is water. Dormant grass will die if the crowns, roots, and rhizomes dehydrate. But there’s no need to water dormant grass unless you’ve gone without significant rainfall for at least four weeks. Depending on the air temperatures and soil conditions, a dormant lawn can survive up to six weeks without water.

If you need to water your lawn, the goal during dormancy is to keep the roots and crowns from dehydrating and dying. Water early in the morning while the grass is already wet from dew, temperatures are cooler, humidity is high, and the wind is calm. These conditions favor the infiltration of water into the soil.

Dry soils have difficulty absorbing water, so to minimize runoff, water for thirty minutes, turn off your sprinkler, then resume watering thirty minutes later. Once the soil is wet, more water will be able to be absorbed, minimizing runoff. Runoff occurs when your irrigation rate (how fast you’re watering the lawn) exceeds the soil’s infiltration rate (how fast your soil can absorb the water).

[su_quote cite=”Healthy Lawns Clean Water” url=”https://healthylawns.suffolkcountyny.gov/lawn/watering.htm”]Measure your soil’s infiltration rate by cutting off both ends of a coffee can and inserting it several inches into the soil. Pour about 1 inch of water into the can and time how long it takes to soak in. Then measure your irrigation rate by placing a coffee can (with the bottom intact) in the area watered by your sprinkler and time how long it takes to fill the can with 1 inch of water. Your irrigation rate should not exceed your infiltration rate.[/su_quote]

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Weed a dormant lawn

Unfortunately, some lawn weeds love the heat and will thrive during your lawn’s dormancy with help from their large taproots. In order to keep weeds from taking over your lawn when the cool temps return, pull them by hand, making sure you remove the taproot as well.

Don’t play on brown, dormant lawns

Heavy foot traffic on brown lawns will make things worse. Encourage your kids to play in a public park or better yet, send them to a swimming pool (or a neighbor’s lawn). Heavy traffic on an already stressed lawn may damage the grass beyond repair and compact the soil.

So have patience. When the summer heat gives way to cooler temperatures and regular rainfall, your lawn will be restored to its former green glory.