Most Wyoming lawns are cool-season grasses, and they want to be mowed between 1.5 and 3.5 inches depending on the species. Tall fescue sits highest at 3 to 3.5 inches. Kentucky bluegrass and fine fescues take 2 to 3 inches. Perennial ryegrass and rough bluegrass run 1.5 to 2.5 inches. Set the mower to the upper end of your range in summer, and never take off more than a third of the blade in one cut.
The mowing height for Wyoming lawns
Height by species
Mowing height is a trade between density and depth. A shorter cut gives a tighter, finer-looking turf, but it leaves less leaf to feed the plant and less shade over the soil. Each of the five cool-season grasses that suit Wyoming has its own window where it keeps both in balance. The numbers below are consistent with the range that land-grant extension guidance gives for each species.
| Grass | Mowing height | Where it sits |
|---|---|---|
| Tall Fescue | 3 to 3.5 inches | The tallest of the five |
| Kentucky Bluegrass | 2 to 3 inches | Middle of the pack |
| Fine Fescues | 2 to 3 inches | Same window as bluegrass |
| Perennial Ryegrass | 1.5 to 2.5 inches | Among the shortest |
| Rough Bluegrass | 1.5 to 2.5 inches | Among the shortest |
The gaps matter. Mow tall fescue at 1.5 inches and you have scalped it. Leave perennial ryegrass at 3.5 inches and it will lodge and mat. If you do not know what is in your lawn, aim for the middle: about 3 inches suits bluegrass blends and fine fescues, and it is only half an inch short of the tall fescue floor.
Why the warm-season grasses are not on the list
Bermudagrass, zoysia and their relatives are missing, and the calendar explains it. The reference station behind the NOAA NCEI normals for this page sits at roughly 6,000 feet and gets about 130 frost-free days. Frost can show up in any month at higher elevations. Warm-season grasses need a long, hot growing season, and they go dormant and brown with the first cold weather. They will not hold a stand against weeds here.
Cool-season species grow in spring and fall, tolerate hard freezes, and keep their crowns alive through a long winter. For a neighboring comparison of a different climate, see How High to Mow a Lawn in Nebraska.
Raising the deck when the heat comes
Summer in Wyoming is short but not gentle. The NOAA NCEI 1991-2020 normals for the reference station show about 5.8 inches of rain across June, July and August combined, out of 15.4 inches for the whole year. June brings 2.16 inches, July 2.11, and August only 1.52, making it the driest of the three. Those are what a region like this can usually expect, not a forecast, and not a measurement of your yard.
Soil and heat matter as much as the totals. The same inch of rain drains through sand within the day, while clay may hold it for a week. Days at or above 90°F pull water out of soil and leaves fast, and summer rain here often arrives as a single thunderstorm that mostly runs off. A cheap rain gauge in your own yard settles the question better than any regional average.
Taller grass shades the soil, which slows evaporation, and a plant with more leaf area can support deeper roots. So when July heat arrives, move to the upper end of your species window: 3.5 inches for tall fescue, 3 inches for Kentucky bluegrass and fine fescues, 2.5 inches for perennial ryegrass and rough bluegrass. Do not drop back to the low end until cooler weather returns.
Raise the deck before the stress, not during it. A scalped patch on dry clay or sand can take weeks to knit back together. If hot, dry weather leaves the grass growing very slowly, mow less often rather than lower. Brown tips after a cut mean a dull blade, so check that too.
The one-third rule, and why it is not arbitrary
Never remove more than one third of the leaf blade in a single mowing. Say you keep a Kentucky bluegrass lawn at 3 inches. The rule says you cut when the grass reaches 4 inches, taking off 1 inch. Let it reach 6 inches and a cut back to 3 inches removes half the plant at once.
Leaves are the plant’s solar panels. They make the sugars that fuel root growth and recovery from every cut, and a hard cut shuts down a large share of that production overnight. The grass then draws on stored reserves to regrow leaves instead of building roots, which is the wrong trade in a dry Wyoming summer. Scalped lawns also open gaps for weeds.
Work the rule out for your own grass:
- Tall fescue at 3.5 inches: cut when it reaches about 5.25 inches.
- Kentucky bluegrass or fine fescues at 3 inches: cut at 4.5 inches.
- Perennial ryegrass or rough bluegrass at 2.5 inches: cut at 3.75 inches.
Set your schedule by the grass, not the calendar. In a fast spring flush you may need to mow twice a week. In a dry August, once every ten days or so might do. If the lawn has outgrown the rule while you were away, do not chop it back in one pass. Mow down a third, wait a few days, then mow again.
For the broader routine around the cut itself, including blade care and clippings, see Mowing a Lawn. To see how the same principles play out in a milder, wetter climate, How High to Mow a Lawn in Connecticut offers the contrast.
The first and last cut of the year
In the NOAA NCEI 1991-2020 Climate Normals for the reference station, the last spring frost at 32°F falls between May 7 and May 18 (the 30 to 70 percent probability band). The first fall frost falls between September 24 and October 5. Those dates describe one high-elevation station, not the whole state. Lower valleys will run earlier or later, and higher ground can see frost in any month, so watch your own thermometer.
Starting in spring
Mow when the grass has actually grown enough to cut, usually after soil warms and the lawn greens up. Make the first cut at your normal height for the species, not shorter. Scalping in early spring to remove dead grass exposes crowns to a late freeze and sets the lawn back just when it should be growing. Sharpen the blade before the season starts so the first cuts are clean rather than ragged.
Finishing in fall
Keep mowing as long as the grass grows, which usually means into the window around the first fall frost. Growth slows well before it stops, so you may be mowing only every two weeks by then. For the final cut, stay inside the range for your species and favor the lower end, because very tall grass tends to mat under snow and invite disease. Do not go below the bottom of the range, and keep following the one-third rule. Rake or mulch-mow leaves before they smother the grass.
Common questions
What is the best mowing height for a Wyoming lawn if I do not know my grass type?
Set the mower to about 3 inches. That sits inside the range for Kentucky bluegrass and fine fescues (2 to 3 inches), at the upper edge of perennial ryegrass and rough bluegrass (1.5 to 2.5 inches), and just under the tall fescue range (3 to 3.5 inches). Your county office of University of Wyoming Extension can help with identification.
Should I mow shorter in spring to get rid of dead grass?
No. Cutting well below your species range exposes the crowns to cold snaps, and with last spring frost normals running from May 7 to May 18 at the reference station, a freeze can still arrive after the lawn has greened. Rake out debris and mow at your normal height once there is growth to cut.
How often should I mow in summer?
Follow the grass, not a fixed day. Mow when it has grown one third above your target height. With only about 5.8 inches of rain across June, July and August at the reference station, growth often slows in July and August, so every ten days or so may be enough.
Can I grow Bermudagrass or another warm-season grass in Wyoming?
It is a poor bet. The reference station gets roughly 130 frost-free days at 6,000 feet, and frost can occur in any month at higher elevations. Warm-season grasses need a long, hot season and go dormant with the first cold. Tall fescue, Kentucky bluegrass, fine fescues, perennial ryegrass and rough bluegrass are the species that hold up.