How High to Mow a Lawn in California

The right height depends on the grass, and the gap between species is wide. Bermudagrass, Zoysiagrass, Seashore Paspalum and Carpetgrass want 1 to 2 inches. Centipedegrass wants 1.5 to 2 inches. St. Augustinegrass wants 2.5 to 4 inches, and Bahiagrass wants 3 to 4 inches. Mow a St. Augustine lawn at Bermudagrass height and you scalp it. Do the reverse and a fine-bladed lawn turns shaggy and thatchy.

The mowing height for California lawns

The spread comes from how each grass grows. Bermudagrass, Zoysiagrass and Seashore Paspalum spread by low runners and build a dense mat that tolerates close cutting. St. Augustinegrass and Bahiagrass carry their leaf area higher, on broader blades, and they lose vigor when it is shaved off. Each species keeps its energy factory (the leaf) at a different height, and the mower should respect that.

These figures sit within the ranges published by land-grant extension programs, including Clemson Cooperative Extension and UF/IFAS Extension. All seven are warm-season grasses, and that is the reason they are the ones listed for California lawns in the hot, dry parts of the state. A cool-season grass peaks in mild weather and stalls in sustained heat. In a region where summer brings almost no rain (more on that below), keeping one green means irrigating through the exact months when water is most restricted and evaporation is highest. That is a poor bargain.

One caution on scope. The climate figures in this article come from NOAA’s Los Angeles reference station, and they describe coastal and southern California. They do not describe the whole state. Northern California, the Central Valley and the Sierra each have their own heat, rainfall and freezes, so a gardener there should check local guidance, starting with UC Agriculture and Natural Resources. The species heights, though, stay the same wherever the grass grows.

If you are comparing climates, the Southeast grows several of the same grasses with much more summer rain. See How High to Mow a Lawn in Georgia and How High to Mow a Lawn in North Carolina for how the same species are handled there. For the mechanics of the cut itself, Mowing a Lawn covers technique.

Raising the deck when the heat comes

NOAA’s 1991-2020 normals for the Los Angeles reference station show about 0.1 inches of rain across June, July and August combined. June averages 0.08 inches, July 0.04, and August 0.0. The whole year adds up to 12.2 inches. A summer lawn here lives almost entirely on irrigation.

That is why the deck matters. Taller grass shades its own soil, which slows evaporation, and it supports a deeper root system that can reach water the surface has lost. For grasses with a range, summer is the time to move toward the top of it: 4 inches for St. Augustinegrass or Bahiagrass, and 2 inches for Bermudagrass, Zoysiagrass, Seashore Paspalum, Carpetgrass or Centipedegrass. Moving up a notch costs nothing and reduces water demand.

Rainfall never tells the whole story, though. The same inch behaves differently by soil. On sand, water drains through within the day, so even a wetter place can need watering every second day. On clay, the surface holds moisture for about a week. Heat changes the math too. Days at or above 90°F pull water out of the soil fast, and a single summer thunderstorm mostly runs off instead of soaking in. In practice, a dry Los Angeles-area summer means the lawn gets only what you apply.

Treat those normals as what the region can usually expect, not a forecast for your yard. A hill, a rain shadow or a dense neighborhood can shift the numbers. A cheap rain gauge on your own lot settles it, and it will also tell you how much your sprinklers actually deliver. If you are under watering limits, taller grass, a sharp blade and leaving clippings on the lawn all help the grass stretch what it gets.

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 folk wisdom, but it follows from how grass feeds itself. Leaves make the sugars that fuel the roots. Cut off too much at once and the plant has to pause root growth while it rebuilds leaf area. A lawn scalped in this way can look fine for a few days, then thin out and open the door to weeds.

The rule turns into a simple schedule. If you keep St. Augustinegrass at 3 inches, mow when it reaches 4.5 inches, which removes 1.5 inches, exactly one-third. If you keep Bermudagrass at 1 inch, mow when it reaches 1.5 inches. The shorter the target, the more often you mow. A close-cut Bermudagrass lawn may need cutting far more often than a Bahiagrass one, because the margin for error is half an inch rather than an inch or more.

Skip a week and the grass overshoots? Don’t drop straight back to the target. Take off a third, wait a few days, then take off another third until you are back in range. The lawn gets through it with a lot less stress than it would from one hard cut.

One more habit pairs with the rule: keep the mower blade sharp. A dull blade tears the leaf tip instead of slicing it, leaving a ragged, browning edge that loses more water, which matters in a climate with almost no summer rain.

The first and last cut of the year

Many gardeners elsewhere in the country plan their season around frost dates. At the Los Angeles reference station, there is no date to give. NOAA’s records show no freeze in an average year, with zero days at or below 32°F in 30 years, and the frost-free season is listed as 365 days. The constraints here are heat, drought and water restrictions, not frost.

For coastal and southern lawns, that means the mowing season does not really end. Warm-season grasses slow down in the cooler, shorter days of winter, but they do not necessarily go fully dormant. The first cut comes when the lawn starts growing noticeably and the grass begins to need mowing, and the last cut comes when growth tapers off. Between those points, follow the one-third rule and mow when the grass tells you to, not by the calendar.

Northern California, the Central Valley and the Sierra are different, because they do freeze. A warm-season grass there can turn brown after a hard freeze and stay that way until it warms up. Specific frost dates for those areas are not published here, so check with your local extension office rather than borrowing a date from Los Angeles. The principle holds: make the first cut once the grass is actively growing again, and make the last one before it shuts down.

One adjustment is worth keeping at both ends of the year. When you are about to head into the slow season, hold the grass at the upper half of its range. A bit of extra leaf gives a lawn some reserve when growth is slow, and it makes the spring restart gentler.

Common questions

What is the best mowing height for a California lawn?

It depends on the grass. Bermudagrass, Zoysiagrass, Seashore Paspalum and Carpetgrass do best at 1 to 2 inches. Centipedegrass runs 1.5 to 2 inches, St. Augustinegrass 2.5 to 4 inches, and Bahiagrass 3 to 4 inches.

Should I mow shorter in summer to save work?

No. Go the other way. Raising the deck to the top of your grass’s range shades the soil and cuts water loss. In a dry summer, with about 0.1 inches of rain from June through August at the Los Angeles reference station, that helps.

How often should I mow?

Mow when the grass has grown about half again as tall as your target, so you never remove more than one-third. A lawn kept at 1 inch needs cutting at about 1.5 inches.

Does California have a first and last frost date?

Not on the coast or in the south. At the Los Angeles reference station there is no freeze in an average year. Northern California, the Central Valley and the Sierra do freeze, so those gardeners should use local guidance.