· by Michael Blair, Nashville's Lawn Care
Mowing height is the cheapest thing you control on a lawn, and it’s the first setting we check when we start mowing a new yard. The right number depends on the grass. If you aren’t sure whether yours is fescue or bermuda, our post comparing the two will help you tell them apart. What follows are the heights the extension services give for each grass, and why the extra blade length matters most once a Middle Tennessee summer sets in.
The heights that work here
Tall fescue wants more height than most mowers are set to give it. NC State Extension’s tall fescue maintenance calendar says to mow to 3 1/2 inches from June through August, before the grass gets taller than 5 inches, and it gives 2 1/2 to 3 1/2 inches for spring and 2 1/2 to 3 for fall. Clemson Extension’s fact sheet on mowing lawns puts summer fescue at 3 to 3 1/2 inches. Bermuda sits far lower. Clemson lists common bermudagrass at 1 to 2 inches and the hybrids at 1/2 to 1 1/2, and the NC State bermudagrass calendar adds that holding a lower height means mowing more often to prevent scalping. It can take the low cut because it spreads by runners above and below the ground, as Clemson’s bermudagrass fact sheet describes, and Clemson’s mowing sheet notes that a grass spreading sideways can usually be mowed shorter than an upright bunch-type grass.
Zoysia falls between the two. Clemson’s mowing table gives it 1 to 2 inches, its zoysiagrass fact sheet says most varieties thrive at around 2 inches, and NC State’s zoysiagrass calendar says to mow it before it grows taller than 1 1/2 to 2 1/2 inches. The error to avoid is a fescue lawn mowed down at the height a bermuda lawn wants. NC State’s fescue calendar is plain that tall fescue does not tolerate close mowing.
Why does mowing height matter more in July?
Blade length and root depth track each other. Virginia Cooperative Extension’s guide to summer lawn watering says mowing on the taller side of the recommended height increases the depth of the root system and improves drought tolerance, and a deeper root has more soil to draw water from in a dry spell. The same guide says to raise cutting heights on cool-season lawns before summer stress arrives, so the deck should go up in late spring, ahead of the heat.
Taller grass also shades the soil, which the Virginia guide credits with minimizing evaporation losses, and Clemson’s mowing sheet says turf under heat, drought or shade stress should be cut higher. There is a ceiling. Clemson’s fact sheet on brown patch warns that mowing too high slows leaf drying and can make the disease worse, and it says not to mow fescue higher than 3 1/2 inches. So through July our crews keep fescue at the top of its range without letting it run long. If your fescue browns out anyway, our post on why lawns go brown in July goes through the usual causes.
How much grass can come off in one cut?
Never remove more than a third of the blade in a single cut. Clemson calls removing no more than one-third of the grass height at any one mowing a good rule of thumb, and it warns that cutting off more than that at one time can stop the roots from growing and leave the lawn needing frequent watering through a dry summer. That is the root system a fescue lawn leans on in August.
In practice that means mowing by growth instead of by the calendar. NC State’s fescue calendar says keeping to the one-third rule may mean mowing every five to seven days in late spring. At a summer height of 3 1/2 inches, the rule puts the next cut at about 5 inches, the same ceiling NC State gives for June through August. If the lawn has got away from you, Clemson’s advice is to raise the mowing height, then lower it gradually over later mowings until you are back at the recommended height. Our post on weekly or biweekly mowing covers what that means for a service schedule.
Blades, clippings and the rest
A dull blade tears the grass instead of cutting it. Clemson’s mowing sheet says a dull blade turns the leaf brown at the point of impact and gives the lawn a general brown cast, and that torn, bruised plants are weakened and less able to recover from disease and insect attacks. In our humidity that matters, because NC State rates tall fescue highly susceptible to brown patch, which it says develops under high humidity when temperatures are above 85°F; our post on brown patch in fescue covers how to spot it. The Virginia guide says simply to keep the mower blade sharp. If the cut tips across your lawn turn brown, look at the blade before you look at anything else.
Leave the clippings in most cases. NC State’s fescue calendar says they decompose quickly and can provide up to 25 percent of the lawn’s fertilizer needs, and Clemson puts their nitrogen content at about 4 percent. The exceptions are disease and excess: Clemson’s brown patch sheet says to remove clippings when the weather is warm and moist so the disease isn’t spread during mowing, and NC State says that when rain delays mowing and clippings are too plentiful to leave, they should be collected and used as mulch. As for thatch, NC State says it is generally not necessary to remove it from tall fescue. Its zoysiagrass calendar ties zoysia thatch to mowing too infrequently, over-irrigating and excessive fertilizer, and Clemson notes that bermuda’s rapid growth can make thatch buildup a problem.
Our weekly mowing service sets the deck by the grass in each yard and changes it with the season. If you’d like us to take over yours, ask us for a free estimate.
Sources
- NC State Extension, AG-367 Tall Fescue Lawn Maintenance Calendar — Fescue mowed to 3 1/2 inches June through August, before it passes 5 inches; 2 1/2 to 3 1/2 in spring and 2 1/2 to 3 in fall; one-third rule and five-to-seven-day mowing in late spring; does not tolerate close mowing; clippings decompose quickly and supply up to 25 percent of fertilizer needs, collect as mulch when too plentiful; thatch removal generally not necessary; highly susceptible to brown patch under high humidity above 85°F
- NC State Extension, AG-431 Bermudagrass Lawn Maintenance Calendar — A lower bermudagrass height requires more frequent mowing to prevent scalping
- NC State Extension, AG-432 Zoysiagrass Lawn Maintenance Calendar (2025) — Mow zoysia before it grows taller than 1 1/2 to 2 1/2 inches; zoysia thatch follows infrequent mowing, over-irrigation or excessive fertilizer
- Clemson Cooperative Extension HGIC 1205, Mowing Lawns — Table 1 heights: tall fescue summer 3 to 3.5 in, common bermudagrass 1 to 2, hybrid bermudagrass 0.5 to 1.5, zoysiagrass 1 to 2; spreading grasses mowed shorter than bunch-type; stressed turf cut higher; one-third rule and root growth; raise then gradually lower an overgrown lawn; dull blades brown the tips and weaken plants against disease; clippings about 4 percent nitrogen
- Clemson Cooperative Extension HGIC 1208, Bermudagrass — Bermudagrass spreads by stolons and rhizomes; rapid growth can make thatch buildup a problem
- Clemson Cooperative Extension HGIC 1212, Zoysiagrass — Most zoysiagrass varieties thrive at a mowing height around 2 inches
- Clemson Cooperative Extension HGIC 2150, Brown Patch & Large Patch Diseases of Lawns (2025) — Mowing too low or too high can increase disease severity; do not mow fescue higher than 3 1/2 inches; remove clippings in warm, moist weather to avoid spreading the disease
- Virginia Cooperative Extension 430-010, Summer Lawn Management: Watering the Lawn — Taller mowing deepens roots, shades the soil, minimizes evaporation and improves drought tolerance; raise cool-season cutting heights before summer stress; keep the mower blade sharp
FAQ
How Short to Cut Grass in Tennessee Heat — questions
Is it bad to cut grass short before a holiday?
Yes, particularly in summer. Clemson Extension says turf under heat or drought stress should be mowed higher, and Virginia Cooperative Extension says to raise cutting heights on cool-season lawns before summer stress arrives. Cutting at normal height the day before you leave is better than a low cut, even if the lawn is long when you get back. When you return, raise the deck for the first cut and bring it down gradually over the next few mowings instead of taking it all off at once.
How often should I mow in a Nashville summer?
By growth, not by calendar. NC State Extension says fescue may need mowing every five to seven days in late spring to stay within the one-third rule. In summer, with fescue held at 3 1/2 inches, cut it before it passes about 5 inches. Bermuda kept low needs mowing more often to avoid scalping.
Should I bag or mulch clippings?
Mulch, in almost every case. NC State Extension says clippings decompose quickly and can supply up to a quarter of a fescue lawn’s fertilizer needs. Collect them when brown patch is active in warm, moist weather, which Clemson Extension advises to avoid spreading the disease, or when the grass has grown long enough that the clippings would sit in clumps on the turf.
How do you care for a fescue lawn?
Mow it tall, at about 3 1/2 inches in summer and 2 1/2 to 3 in fall, cutting before it passes about 5 inches and never taking more than a third at once. Keep the blade sharp, leave clippings except when brown patch is active, and skip dethatching, which NC State says fescue generally doesn’t need.