Ornamental · Poaceae
St. Augustine Grass
Stenotaphrum secundatum
A little warmth, faithful watering, and a tall cut turn St. Augustine grass into the plush, carpet-like lawn a Southern yard is built around.
Full sun
Every 3–7 days
60–365 days
USDA 8–10
Overview
St. Augustine grass is the signature lawn of the warm, humid South, the green expanse that frames porches, patios, and long summer evenings outdoors. A coarse-bladed turf that travels on above-ground runners called stolons, it settles into a dense, carpet-like sweep underfoot, ideal for bare feet and backyard gatherings. It greens up early and holds its color through the heat, which is why it defines so many landscapes across the Gulf Coast and Florida. A touch of shade tolerance lets it soften the edges of a tree-lined yard, though it looks its most polished where the sun pours in.
Think of it as a warm-climate perennial with a clear sense of season. It comes alive in the heat, then slips into a quiet brown dormancy as winter settles in, and a hard freeze can thin or undo a lawn left unguarded. That love of warmth is what makes it so at home across the Gulf states, where outdoor living runs nearly year-round and the cold rarely overstays.
The reward of such a lush, quick lawn is a routine that keeps it looking its best. St. Augustine grass asks for regular water and steady feeding, and it invites more pests and diseases than some turfs, the southern chinch bug chief among them. Mow it high, water it deep, and keep the nitrogen measured, and it returns a thick, even carpet that anchors the whole yard.
Care
The short version: set it in sun to part shade, keep the soil evenly moist with about 1/2 to 3/4 inch per watering, mow it tall at 3 to 4 inches, and feed it nitrogen through the warm season with a light touch.
Light
St. Augustine grass looks its best in full sun, yet it tolerates partial shade more graciously than most warm-season lawns, an asset in a yard with mature trees. Give it as much light as the space allows for a full, even sweep, since deep shade leaves the turf thin and lackluster.
Water
Keep the soil evenly moist, watering when the blades fold, wilt, or turn a blue-gray cast, with about 1/2 to 3/4 inch at each session. The lawn wants steady moisture and only tolerates moderate drought, so a dry spell should not run on too long.
Soil
It adapts to many soils but settles happiest in well-drained ground at a medium to low pH, roughly 6.0 to 7.5. Where the soil turns alkaline the blades can pale, and a measured dose of iron restores the green.
Temperature
A warm-season grass at heart, it thrives through heat as high as about 95°F (35°C). Cold is its limit: it fades into a brown winter dormancy, and a hard freeze near 25°F (-4°C) can thin or undo an unprotected lawn.
Humidity
It feels perfectly at ease in high humidity, part of why it flourishes along the muggy Gulf Coast. That same warm, damp air can invite a few fungal diseases, so airflow and mowing dry blades matter more to a healthy lawn than the humidity itself.
Feeding
Feed it nitrogen across the warm season, somewhere between 2 to 6 applications a year to match the climate. Keep a light hand with quick-release soluble nitrogen, which tends to feed chinch bug damage rather than the lawn.
Pruning
Mow standard cultivars tall, at 3 to 4 inches, and dwarf types a touch lower, near 2 to 2.5 inches, to keep the surface even. Never remove more than a third of the blade in one pass, or the lawn frays and weeds find their opening.
Repotting
none
Size & spacing
Mowed, the blades sit only about 3 to 4 inches (8 to 10 cm) high, while the stolons reach outward so a single plant spreads roughly 1 to 3 feet (30 to 100 cm), weaving neighbors into one continuous expanse.
When to plant
Timing follows the warmth, so the lawn goes in while the season is generous. Lay sod, plugs, or sprigs in spring or from late summer into early fall, sidestepping cold snaps and the driest, hottest stretches. It returns to green each spring and rests in a brown dormancy through the cold, a rhythm that suits the Southern calendar.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Plant: Lay sod, plugs, or sprigs during active warm-season growth in spring or late summer/early fall (late fall to spring in south Florida); avoid cold and hot, dry extremes.
- Harvest: Grown as turf; not flowered or harvested. Greens up in spring and goes dormant/brown in winter cold.
Hardiness
USDA hardiness zones: 8–10
Temperature: down to -12°C
Troubleshooting
When a St. Augustine lawn falters, it usually shows as patches of yellowing or dying turf, and the season sets the story. Read the timing and the shape of the damage, and a summer chinch bug reveals itself apart from a fall fungus. Find the match below and act while the patch is still small.
Yellow-brown patches widening across the sunny, dry stretches
A patch that keeps widening in the sun almost always traces to the southern chinch bug, the pest that troubles St. Augustine grass more than any other. It draws sap along the warm, dry edges through high summer, and the browning turf pushes outward from there. Treat the patch and the healthy grass around it the moment injury appears, ease back on quick-release nitrogen, and water generously, since a heavy soaking or rain sets the population back.
Fix:
- Treat affected and surrounding turf with a labeled insecticide as soon as injury appears, targeting both nymphs and adults
- Avoid excess soluble nitrogen, which accelerates chinch bug buildup
- Irrigate adequately, since heavy irrigation or rainfall suppresses populations
- Consider a resistant cultivar such as Floratam when renovating
Mottled yellow lawn that holds its pallor after feeding
A lawn that turns mottled yellow and stays that way after a feeding likely carries St. Augustine Decline, a virus without a chemical remedy. First rule out an iron or manganese shortage on alkaline soil, which a dose of iron will address. If it is truly SAD, replant with a resistant cultivar such as Floratam or Raleigh, set on 2 to 3 foot centers, and let the healthy grass overtake the failing turf.
Fix:
- Replant with a SAD-resistant cultivar (for example Floratam, Floralawn, Raleigh, or Seville), plugging it in on 2 to 3 foot centers to crowd out diseased grass
- Rule out iron/manganese deficiency on alkaline soil with supplemental iron
- Use clean, virus-free sod or plugs
Round brown patches in the cool, wet seasons, with loosening leaves
Circular patches that surface in the cool, damp weather of fall and spring usually signal large patch, a Rhizoctonia fungus. The tell is at the patch edge, where the blades lift free of dark, rotted sheaths. Hold the feeding for summer when the grass is growing hard, ease off the water, and aerate compacted ground so it drains.
Fix:
- Limit fertilizer to summer when turf is actively growing
- Avoid mowing too low and avoid over-irrigation
- Aerate to reduce compaction and improve drainage
- Apply a preventive fungicide in fall when soil temperatures favor the pathogen
Gray oval spots edged in purple across the blades
Tan-to-gray lesions rimmed in purple are the signature of gray leaf spot, a fungus that surfaces in warm, wet weather on lawns given too much nitrogen. Mow only when the blades are dry and bag the clippings while the spots persist. The lasting remedy is to reduce the nitrogen and keep the leaves from staying wet for long.
Fix:
- Mow at the proper height and only when grass is dry
- Bag and dispose of clippings while disease is active
- Reduce nitrogen and avoid prolonged leaf wetness
- Apply a labeled fungicide if needed
Toxicity
For a household with pets, this lawn is an easy companion: St. Augustine grass is a plain turfgrass with nothing toxic in it. Cats, dogs, horses, and the rest can lounge and graze on it without any risk of poisoning. A pet that swallows a mouthful may bring it up, but that is the blades unsettling the stomach rather than a toxin, and the pollen is the only thing that might trouble an allergy-prone household.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats None
A cat can graze this lawn grass with no harm at all. The most a household might notice is a stray hairball or a little vomiting from the blades, which is mechanical rather than poisoning.
Dogs None
Dogs are safe at play on it and around it. A few will crop a mouthful and bring it back up, but that is the grass unsettling the stomach, not a toxin.
Horses Safe
Horses can graze St. Augustine grass with no risk of poisoning.
Rabbits Safe
Rabbits can nibble the blades safely, as this is a plain turfgrass with nothing toxic in it.
Livestock Safe
Cattle, goats, and sheep can graze it without any trouble.
Birds Safe
Backyard birds and poultry can forage across it freely, as nothing in the plant poses a hazard.
People Safe
The lawn is harmless to people, though its pollen can stir hay-fever symptoms in anyone prone to grass allergies.
The grass is not poisonous. Pets that nibble lawn grass may occasionally vomit, but this is mechanical, not poisoning. Grass pollen can trigger hay-fever-type allergies in sensitive people and pets.
Varieties
St. Augustine grass arrives in several named cultivars, and the right choice suits both the local climate and the pests a yard tends to face. These are the ones worth having on the shortlist.
Floratam
Floratam is the most widely planted cultivar, a coarse and vigorous grass that resists the SAD virus but has little patience for cold or shade.
Palmetto
Palmetto is a favorite for its stronger cold hardiness, though it offers no insect resistance and can struggle with disease in humid climates.
Raleigh
Bred at NC State for cooler northern yards, Raleigh pairs cold hardiness with SAD resistance yet still contends with chinch bugs and large patch.
Seville
Seville is a fine-bladed, dark green dwarf that resists SAD while remaining open to chinch bug and webworm damage.
Captiva
Captiva, a University of Florida dwarf, resists southern chinch bugs and grows low enough to ease the mowing routine.
How to propagate
There is no seed packet for this lawn. It advances on its own runners, so plugs, sprigs, and sod are how a yard gets started or a bare corner gets mended.
DivisionEasy
During active warm-season growth in spring or late summer/early fall · Several weeks to a few months for plugs/sprigs to fill in; sod establishes fastest
Begin a lawn in spring or from late summer into early fall, while the grass is growing hard. Since it travels on its own, it goes in vegetatively as sod, plugs, or sprigs, with sod cut into small squares for plugs and set 6 to 24 inches apart, closer spacing closing the gaps sooner. Sod knits together fastest, while plugs and sprigs take several weeks to a few months to fill in, and none of it starts from seed.
Myths
St. Augustine grass can be sown from seed like other lawn grasses.
In truth it sets almost no viable seed, so sowing rarely amounts to a lawn. The dependable path is vegetative, laying sod or planting plugs and sprigs.