How do I take care of St. Augustine grass in Florida?
St. Augustine grass care comes down to three habits: mow high (3.5–4 inches), water deeply but infrequently, and watch for chinch bugs and brown patch fungus — the two problems that ruin more Florida St. Augustine lawns than anything else. It's the most common home lawn grass in Central Florida for good reason (heat and shade tolerance), but it's also particular: cut it too short or water it wrong and it thins, browns, and lets weeds in. Get the basics right and it stays the thick green carpet it's known for.
Key takeaways
- Mow St. Augustine high — 3.5–4 inches — and never cut more than a third at once.
- Water deeply but infrequently to build strong roots; skip irrigation when it rains.
- Chinch bugs (summer, sunny) and brown patch fungus (cool, wet) are the top threats.
- Fertilize during the growing season and follow UF/IFAS rates and local ordinances.
- Brown patches have different causes — identify before you treat.
Table of contents
- Mow high
- Water deeply, not daily
- Fertilizing the right way
- Chinch bugs and brown patch
- Reading brown patches
- Where to start
- FAQ
Mow high
The single most common mistake with St. Augustine is mowing it too short. This grass wants to be tall — about 3.5 to 4 inches for standard varieties like Floratam. Cutting it short might feel tidier, but it stresses the plant, exposes soil to weed seeds, and weakens the root system, leaving the lawn thinner and more vulnerable to everything else.
Two rules make the difference: keep the mower at the right height, and never remove more than a third of the blade in a single mow (so if it's grown long, bring it down in stages). Keep the blade sharp — a dull blade tears rather than cuts, leaving ragged tips that brown and invite disease. Mowing high and clean is free, and it's the foundation everything else builds on.
Water deeply, not daily
Florida lawns are often watered wrong — a little every day, which trains shallow roots and wastes water. St. Augustine does far better with deep, infrequent watering: roughly ½ to ¾ inch applied when the grass tells you it's thirsty (blades folding, a bluish-gray cast, footprints staying visible). Deep watering pushes roots down, building a more drought- and stress-tolerant lawn.
Let nature help. During the summer wet season, our afternoon storms often handle the watering, so run irrigation only when rain hasn't — a rain sensor (required on Florida irrigation systems) keeps you from watering in a downpour. Overwatering is its own problem: constantly soggy grass invites fungus and shallow roots. Watering deep and only as needed also keeps your bill down, a common driver behind a higher-than-expected water bill.
Fertilizing the right way
Feed St. Augustine during its active growing season — generally spring through early fall in Central Florida — and don't fertilize dormant, drought-stressed, or struggling grass, which can't use it and may be harmed. Use a fertilizer suited to St. Augustine and follow the UF/IFAS recommended rates; more is not better, and excess nitrogen actually encourages thatch and some pests.
One Florida-specific point: many counties and cities have fertilizer ordinances that restrict application during the summer rainy season (to protect waterways from runoff), so check your local rules before feeding. The University of Florida's UF/IFAS St. Augustine grass guidance is the authoritative reference on timing, rates, and care. If this feels like a lot to track, a lawn care company can handle the fertilization schedule correctly.
Chinch bugs and brown patch
Two problems do most of the damage to Florida St. Augustine, and they strike in opposite conditions. Chinch bugs are the summer scourge: they thrive in hot, sunny areas and suck the juices from the grass, creating expanding brown or yellow patches, often along sidewalks and driveways and in the sunniest parts of the yard. They spread fast in peak heat, so catching them early matters — our guide on chinch bugs in St. Augustine grass covers identification and treatment.
Brown patch fungus (large patch) is the flip side: it shows up in cool, wet conditions — typically fall through spring — as roughly circular brown patches, often with a yellowing edge. It's driven by moisture, so overwatering and watering in the evening (leaving grass wet overnight) feed it. The treatments are completely different — an insecticide for chinch bugs does nothing for fungus, and a fungicide does nothing for bugs — which is why correctly identifying the cause comes first.
Reading brown patches
Because the fixes differ, here's a quick way to read a browning lawn:
| Sign | Likely cause | Direction |
|---|---|---|
| Spreading brown in hot, sunny spots, summer | Chinch bugs | Insecticide; treat early |
| Circular patches in cool, damp weather | Brown patch fungus | Fungicide; reduce watering |
| Uniform bluish-gray, footprints linger | Drought stress | Water deeply |
| Brown only where you mowed/edged | Scalping or dull blade | Mow higher, sharpen blade |
When in doubt, get it diagnosed before dumping product on the lawn — treating fungus as if it were bugs (or vice versa) wastes money and time while the real problem spreads. A lawn pro or your county extension office can confirm the cause.
Where to start
Start by setting your mower to 3.5–4 inches and shifting to deep, infrequent watering — those two changes fix most struggling St. Augustine lawns. Our lawn care directory and Orlando city page list local lawn companies, with more across the full directory. If you're choosing grass for a new lawn rather than maintaining one, see our guides on the best grass for Florida and sod installation cost. Mow high, water deep, identify problems before treating, and St. Augustine rewards you.
FAQ
How tall should I mow St. Augustine grass? Mow St. Augustine high — about 3.5 to 4 inches for most varieties. Cutting it short stresses the grass, invites weeds, and weakens its roots. Never remove more than a third of the blade in one mow.
How often should I water St. Augustine grass in Florida? Water deeply but infrequently — generally about ½ to ¾ inch when the grass shows signs of thirst, rather than a little every day. Deep, occasional watering builds stronger roots, and you skip irrigation when it rains.
What kills St. Augustine grass in Florida? The most common culprits are chinch bugs (which cause spreading brown patches in sunny areas during summer heat) and brown patch fungus (cool, wet conditions). Improper mowing, overwatering, and thatch also weaken it.
When should I fertilize St. Augustine grass? Fertilize during the active growing season, typically spring through early fall, and avoid feeding dormant or stressed grass. Follow UF/IFAS rates and any local fertilizer ordinances, which restrict application in some seasons.
Why does my St. Augustine grass have brown patches? Brown patches usually mean chinch bugs (summer, sunny spots), brown patch fungus (cool, damp weather), or drought stress. Identifying which one matters, because the fix for bugs, fungus, and dryness is completely different.