9 St. Augustine Mowing Mistakes, and What UF/IFAS Recommends Instead

St. Augustine is the most common lawn grass in Florida and much of the Gulf Coast, and it’s less forgiving than bermuda or zoysia. It spreads by thick above-ground runners, and cutting too low strips away the leaf that keeps them alive. A lot of the brown, thin St. Augustine lawns you see in summer were mowed into that state.

This list covers the nine mowing mistakes that UF/IFAS, the University of Florida’s extension service, warns about, with the fix for each. MowReview quotes no prices and hasn’t tested the products mentioned. How we research explains why.

1. Cutting standard St. Augustine below 3 inches

UF/IFAS’s St. Augustine guide says standard cultivars “should be mowed at 3.5–4 inches.” Its Gardening Solutions guide is blunter: only the dwarf cultivars should be mowed below 3 inches. Repeated low mowing, UF/IFAS says, adds stress, discourages deep rooting and raises the risk of scalping if a mowing is missed, and its mowing guide names mowing below the recommended height as a primary cause of turf death.

The fix: set the deck to 3.5 to 4 inches for Floratam, BitterBlue, Classic and other standard cultivars. Many rotary mowers’ top settings are close to this, so measure from the ground to the blade rather than trusting the notch number.

2. Using the wrong height for your cultivar

Mowing a dwarf cultivar at 4 inches is less harmful than scalping a standard one, but UF/IFAS notes that infrequent or high mowing can contribute to thatch. If you don’t know your cultivar, treat the lawn as standard: cutting a dwarf lawn a little high does less harm than scalping a standard one. A local extension office or sod supplier can usually identify it from a sample.

3. Removing more than a third at once

UF/IFAS says “no more than 1/3 of the leaf blades should be removed with any mowing.” Its mowing guide gives a worked example: St. Augustine kept at 3 inches should be mowed when it reaches about 4 to 4.5 inches.

The fix: for a lawn kept at 4 inches, mow before it reaches about 6 inches. If it’s grown well beyond that, bring it down in two or three mows a few days apart, not all at once.

4. Waiting too long between mows

UF/IFAS suggests mowing about weekly in the growing season, and its mowing guide gives every 5 to 14 days for St. Augustine. Texas A&M’s AgriLife mowing guide explains why long gaps hurt: letting grass grow “hairy” raises the growing point, which can be cut off when you finally mow, and piles of clippings are a sign you’re mowing too infrequently.

In winter, growth slows and you can mow less. UF/IFAS says that in north Florida, winter mowing may not be needed at all.

5. Mowing with a dull blade

UF/IFAS says dull blades shred leaves and give the lawn a brownish cast. It recommends sharpening monthly during the growing season, more often than most homeowners do. Texas A&M adds that ragged, torn tips are entry points for fungal disease and small insects.

The test: look at a few blades a day after mowing. Clean, straight cuts are fine. Frayed, white or brown tips mean it’s time to sharpen.

6. Ignoring shade and drought

UF/IFAS says that “mowing height should be increased during periods of moisture stress or if the grass is growing in shade.” Taller leaf captures more light under trees and shades the soil in dry spells. Shaded St. Augustine also needs less fertilizer than grass in full sun.

Signs your lawn needs water, according to UF/IFAS, include folded or wilting blades, a blue-gray tint, and footprints that stay visible. Mowing a drought-stressed lawn low adds stress on top of stress.

7. Bagging the clippings

UF/IFAS says clippings “should be left on a lawn that is mowed at the proper height and frequency.” They don’t add to thatch and they return nutrients to the soil. If clippings clump after a missed mowing, let them dry and spread them out rather than bagging.

8. Mowing wet grass with a rotary mower

UF/IFAS’s mowing guide says to “never mow wet turf with a rotary mower because clippings can clog the machine,” and that mulching mowers perform poorly on wet or tall turf. In Florida’s summer rainy season, that often means mowing in the afternoon once the morning rain and dew have dried.

9. Mowing the same direction every time

UF/IFAS recommends mowing in a different direction each time. Repeating the same pattern causes wear lines and grain, with the grass leaning one way, and raises the risk of scalping. Alternate between two or three patterns.

The robot mower exception

UF/IFAS’s St. Augustine guide includes a notable finding: robotic mowers “can tolerate lower heights because they remove small amounts of leaf blade frequently,” and UF research kept Floratam at 2.4 inches year-round with no negative effects. A robot that trims a little every day never removes a third of the blade, which avoids mistakes 3 and 4 entirely. It does need a cutting range that reaches 4 inches, so you can still raise it in shade and drought. Robot mowers that cut 4 inches high lists every US model, and robot mowers for St. Augustine covers the rest.

The picks

Questions

How short can I cut St. Augustine grass?

For standard cultivars such as Floratam, UF/IFAS recommends 3.5 to 4 inches, and its Gardening Solutions guide says only dwarf cultivars should be mowed below 3 inches. Dwarf cultivars such as Seville are mowed at 2 to 2.5 inches.

What happens if you cut St. Augustine too short?

UF/IFAS says repeated low mowing adds stress, discourages deep rooting and raises the risk of scalping if a mowing is missed. Its mowing guide calls mowing below the recommended height a primary cause of turf death.

How often should St. Augustine be mowed?

About weekly in the growing season, less often in cooler months, according to UF/IFAS. Its mowing guide gives every 5 to 14 days and says to remove no more than one-third of the blade per mowing.

Should I bag St. Augustine clippings?

No, if you mow at the right height and frequency. UF/IFAS says clippings left on a properly mowed St. Augustine lawn don’t add to thatch and return nutrients to the soil.

Should I mow St. Augustine higher in shade?

Yes. UF/IFAS says to raise the mowing height when St. Augustine is growing in shade or during moisture stress.

Can a robot mower cut St. Augustine?

Yes, and possibly lower than usual. UF/IFAS says robotic mowers can tolerate lower heights because they remove small amounts of leaf often, and UF research kept Floratam at 2.4 inches year-round with no negative effects.

The short version

Keep standard St. Augustine at 3.5 to 4 inches, dwarf cultivars at 2 to 2.5, and never take more than a third at once. Mow about weekly in summer with a blade sharpened monthly, raise the height in shade and drought, leave the clippings, skip wet grass and change direction each time. Or let a robot trim a little every day, which UF research suggests St. Augustine handles well.