How should you water a lawn in summer?
The old advice to water “early in the morning or late in the evening” is half right. Morning is best. Evening is the problem, because blades that stay wet overnight invite disease; UT Extension says plainly not to irrigate at sunset (UT Extension W1068).
Water deeply and let the soil dry between soakings. Actively growing fescue uses about 1 to 1½ inches a week in total, and July storms often supply some of it. Watch the grass rather than the calendar: UT’s irrigation guide describes thirsty turf turning bluish-gray and failing to spring back after you walk on it. That’s the day to water.
How high should you mow in summer?
Raise the deck for fescue. UT Extension recommends moving tall fescue from 2 to 3 inches up to 2½ to 3½ inches before high temperatures arrive (UT Extension W161-I). The taller leaf shades the soil, keeps it cooler and holds moisture. Some older advice says 3 to 4 inches; UT’s range tops out at 3½.
Bermuda is the exception. It stays low, around ¾ to 1½ inches for hybrid types, and lets you know if you let it get tall by scalping when you finally cut it. For either grass, never take more than a third of the blade in one mowing, and mow on cooler, dry days when you can.
Should you fertilize a lawn in summer?
It depends on the grass, and fescue is the one people most often get wrong. For tall fescue, UT Extension’s lawn calendar lists no fertilizer from May through August, and UT’s disease guide names excess spring and summer nitrogen as one of the things that makes Brown Patch worse (UT Extension PB842). Fescue gets its main feeding in fall.
Bermuda and zoysia are the opposite: UT’s calendar has them fertilized through summer, according to a soil test. Our rounds use slow-release nitrogen, and your specialist takes the grass in your yard into account before anything goes down.
What about weeds in summer?
Summer weed control starts in spring. A pre-emergent applied once soil temperatures average 55°F keeps most crabgrass from ever sprouting. Whatever gets through, along with nutsedge, is spot-treated with a post-emergent herbicide. Read the label’s temperature limits first, because many weed killers can injure the lawn itself in high heat. The longer-term fix is the same as always: thick, properly mowed grass leaves weeds nowhere to start.
Is summer the time to aerate?
For fescue, not yet. UT’s calendar puts aerating and overseeding tall fescue in late summer, and its fescue guide prefers September, when the seed gets cooling nights. Bermuda and zoysia are the grasses to aerate in summer, while they’re actively growing (UT Master Gardener, turfgrass). Either way, a thin layer of compost spread after aerating improves clay soil over time.
What pests and diseases show up in summer?
- Brown Patch. Tan patches in fescue, sometimes with a smoky gray ring at the edge in the morning, during hot, wet weather. Expect it from May through July. The LawnWise Premier program adds a fungicide round that goes on before symptoms show.
- White grubs. UT Extension suggests checking for them from mid-July to early August.
- Fall armyworms. Despite the name, UT’s calendar says to start watching for them in July. They chew circular bare areas fast.
- Mosquitoes. They don’t hurt the grass, but they can make the yard unusable. Our mosquito treatments run monthly from May through September.
See the rounds in each LawnWise lawn program, or book a free evaluation if something in your yard looks off this summer.