Lawn care in Utah: grass types, mowing and feeding

Most Utah lawns are cool-season grasses, and USU Extension describes each one by what it does best.^[1]

USU does not recommend bermudagrass as a turf and calls common bermudagrass an established weed in many southwestern lawns and gardens.^[1] In the St. George area, USU lists both cool-season and warm-season grasses on its calendar, with warm-season grass seeded in spring or early summer.^[2]

Keep cool-season lawns at least 2½ to 3 inches tall through the growing season, and never remove more than a third of the blade at once. A 4-inch lawn should not be cut below 3 inches.^[3] Leave the clippings on the lawn; USU says that cuts soil evaporation.^[4] For the last mow of the year, cut to about 1½ inches.^[5]

In the fall, mulch leaves into the lawn when they are 1 to 2 inches deep or less.^[3]

USU's turf calendars recommend 2 to 4 pounds of nitrogen per 1,000 square feet each year, applied about 1 pound at a time, and a soil test for phosphorus and potassium every two or three years.^[5] The most important feeding of the year comes in late October or early November, after the last mowing: 1 pound of quick-release nitrogen per 1,000 square feet.^[3]

Most home lawns need aeration no more than once a year, if at all. Spring (April or May) and fall (September or October) are the usual times.^[3] USU calls for a hollow-tine aerator with tines 3 to 4 inches long and ¼ to ¾ inch across, run in one direction and then again at 90 degrees.^[2]

September and October are generally good months to overseed cool-season grass.^[3] USU says to allow 4 to 6 weeks before the expected first frost, and in the St. George area late summer is the best time to seed cool-season grass.^[6][2] A new lawn or repair started in August has 4 to 6 weeks before heavy frost.^[7]

Apply pre-emergent herbicide from late March to mid-April for crabgrass and spurge, with a second application in late May or early June.^[7] For broadleaf weeds, treat when temperatures are between 60 and 80°F and stop once it is above 85°F.^[7] Follow the label on any product.

USU Extension's guidance on practical turf is blunt: keep grass where it does a job, such as play areas, high-traffic areas, and spots that need cooling, noise or dust control. If a patch is only walked on when it is mowed, a lower-maintenance planting may serve better. Skip turf in narrow, small or oddly shaped areas that are hard to irrigate efficiently, and give the lawn its own irrigation zone separate from other plants.^[4] USU also suggests that some lawns can go unirrigated: many grasses go dormant in drought and green up when conditions improve.^[4]

If you want a lower-water lawn, the Division of Water Resources suggests grass seed carrying the Turfgrass Water Conservation Alliance stamp. Salt Lake City and Provo sell approved seed at a reduced cost through their Turf Trade programs.^[8]