How High to Mow a Lawn in Arizona

Mow an Arizona lawn at the height its grass species needs. That is 1 to 2 inches for Bermudagrass, Zoysiagrass, Seashore Paspalum and Carpetgrass, 1.5 to 2 inches for Centipedegrass, 2.5 to 4 inches for St. Augustinegrass, and 3 to 4 inches for Bahiagrass. The ranges sit far apart. Cut one species at another’s height and you can lose the lawn in a few weeks. In summer, set the deck at the top of your range.

The mowing height for Arizona lawns

Mowing height is a trade. Taller blades give the plant more leaf surface to capture sunlight and more shade over the soil. Shorter blades give a tighter, finer-looking turf but leave less margin for error. Each grass has a window where that trade works, and the window depends on how the plant grows. Creeping, dense grasses like Bermudagrass tolerate low cuts. Broad-bladed, coarser grasses like St. Augustinegrass and Bahiagrass need height to stay healthy.

The heights below come from extension sources, including Clemson Cooperative Extension, UF/IFAS Extension and the University of Georgia Extension. Each figure sits within the ranges those sources give.

All seven are warm-season species, and that is the whole list for a reason. Cool-season grasses such as bluegrass and fescue do their best growing in mild weather and slow down when heat sets in. Arizona’s low desert serves up months of it, with plenty of days at or above 90F, so a cool-season turf struggles to hold through the summer. Penn State Extension covers those species for cooler climates. Our How High to Mow a Lawn in New Jersey page is the place for their heights.

One caution on the list. It names the species recommended across warm-season country, not a promise that each performs equally well at your elevation or water budget. Your county office at University of Arizona Extension can tell you which of these suit your yard. If you already have a lawn and do not know what it is, identify the grass first. Mowing a Bermudagrass lawn at 4 inches wastes it, and mowing St. Augustinegrass at 1 inch can scalp it.

Raising the deck when the heat comes

Summer is when the top of your range earns its keep. A taller canopy shades the soil, which slows evaporation from the surface, and it keeps the crown of the plant a little further from reflected heat. For Bermudagrass, Zoysiagrass, Seashore Paspalum and Carpetgrass, that means moving toward 2 inches. For Centipedegrass, stay near 2 inches. For St. Augustinegrass and Bahiagrass, move toward 4 inches.

Rainfall will not do the work for you. NOAA NCEI Monthly Climate Normals for 1991-2020, at the Phoenix reference station, put summer rain at about 1.9 inches across June, July and August combined, out of 7.2 inches for the year. June is the driest month at 0.02 inches. July comes in at 0.91 inches and August at 0.93. So the stretch when grass is most stressed is also when the sky contributes next to nothing.

Those numbers never tell you how often to water by themselves. Soil changes everything: an inch of rain slips through sand within the day, while clay holds it for about a week. Heat changes it again, because days at or above 90F pull moisture out of the ground quickly. And summer rain here tends to arrive as a single thunderstorm, which mostly runs off hard ground instead of soaking in. A lawn on sandy soil can need water every second day even in a wetter month, and a clay lawn may coast longer.

These are normals from one station over a 30-year window. They are not a forecast, and they are not your yard. A slope, a rain shadow or a neighborhood on the other side of town can all differ. A cheap rain gauge on your own lot is what settles it. Check it after each storm, and cut watering only when the gauge says the soil really got the water.

Raising the deck is the free half of heat management. The mower setting costs nothing, and a lawn that stays a notch taller through July usually needs less rescue in September. Dial it back down only when the weather cools and growth picks up again.

The one-third rule, and why it is not arbitrary

Never remove more than one-third of the blade height in a single mowing. It sounds like a rule somebody made up, and it is easy to ignore on a hot weekend when the grass has gotten ahead of you. But it follows how the plant feeds itself. Leaves make the sugars that roots and stems live on. Take off too much at once and the grass has to rebuild leaf area using reserves, at exactly the time the heat is already costing it energy.

The arithmetic is simple. If you keep St. Augustinegrass at 4 inches, mow it when it reaches 6 inches. Keep Bahiagrass at 3 inches and the trigger is 4.5 inches. A Bermudagrass lawn held at 2 inches should be cut when it reaches 3 inches, and a Seashore Paspalum lawn held at 1 inch when it reaches 1.5 inches. The shorter the target, the more often the mower has to run. A lawn at 1 inch is on a tight schedule, which is part of why the low-cut species are more work than they look.

If the lawn got too tall

A lawn that has gotten away from you, say after a trip, should not be dropped back to its target in one pass. Cut it down by a third, wait a few days, then cut again until you reach the right height. The same logic applies in reverse when summer ends and you lower the deck. Step down, do not drop.

The payoff shows up on the heat days. Scalped grass exposes stubble and bare soil to full sun, and brown patches follow. For general technique that applies in any state, see our guide to Mowing a Lawn.

The first and last cut of the year

Most of the country plans the first mow around the last spring frost. Phoenix does not work that way, and neither should a mowing calendar built on it. At the NOAA NCEI 1991-2020 reference station for Phoenix, most years bring no freeze at all, and NOAA lists the frost-free season as 365 days. The station reached 32F in only 6 of 30 springs. When a cold snap does arrive, it lands between late December and mid January. There is no reliable fall freeze either.

So the signal for your first cut is the grass itself. A warm-season lawn stops growing when it cools off and picks up again as it warms. When blades have clearly greened up and begun to grow past your target height, mow. Start at the top of your species range on that first pass, since the roots are still waking up, and bring it down only as growth speeds up. Your last cut is the mirror image. Once growth slows in cool weather and the lawn no longer outgrows the target between mowings, you can stop, leaving it at the upper end of the range.

That advice comes from Phoenix figures and does not stretch across the state. Flagstaff and the high country are a different climate entirely. Hard freezes happen there, warm-season grass goes dormant for much longer, and the first mow comes later. If you live above the low desert, ask your county University of Arizona Extension office for local timing. For contrast, How High to Mow a Lawn in Georgia shows how a frost-based calendar looks in a humid Southern state.

Common questions

What is the best mowing height for Bermudagrass in Arizona?

Bermudagrass is mowed at 1 to 2 inches. In summer, lean toward 2 inches. Going below 1 inch is where scalping starts.

Can I mow St. Augustinegrass at 1 inch?

No. St. Augustinegrass belongs at 2.5 to 4 inches. A cut at 1 inch is far below that range and risks scalping the lawn.

Do I mow differently on a dry summer day?

Raise the deck toward the top of your species range and keep to the one-third rule. June averages only 0.02 inches of rain at the Phoenix reference station, so the grass gets no help from the sky.

When should I do the first mow of the year in Arizona?

When the grass has greened up and is clearly growing. In Phoenix there is no reliable frost date to wait for. In Flagstaff and the high country, freezes happen, so check with your county extension office.