St. Augustine grass care
Stenotaphrum secundatum dominates lawns across the Gulf Coast, Florida, and Hawaii -- and for good reason in those climates. It handles more shade than any other common warm-season grass, spreads aggressively by stolons, and produces a thick, coarse carpet that crowds out weeds. The trade-offs are.
—- title: "St. Augustine grass care" slug: st-augustine-grass-care hub: lawn category: "Lawn guide" description: "St. Augustine grass care guide covering watering, fertilization, chinch bug management, and SAD virus, based on Texas A&M AgriLife and UF IFAS research." date: 2026-06-10 updated: 2026-06-10 author: "Thomas A." reading_time: 8 —-
Stenotaphrum secundatum dominates lawns across the Gulf Coast, Florida, and Hawaii — and for good reason in those climates. It handles more shade than any other common warm-season grass, spreads aggressively by stolons, and produces a thick, coarse carpet that crowds out weeds. The trade-offs are real: it requires consistent moisture, is magnetically attractive to chinch bugs and grey leaf spot, and is highly susceptible to St. Augustine Decline (SAD) virus.
Species and cultivar background
Several cultivars of Stenotaphrum secundatum are in commercial use. Per UF IFAS Extension:
| Cultivar | Notes |
|---|---|
| Floratam | Most common; chinch bug and SAD resistance was lost due to biotype changes |
| Palmetto | Semi-dwarf; SAD resistant; better shade tolerance |
| CitraBlue | Fine texture; good shade and cold tolerance; released 2019 |
| ProVista | Herbicide-tolerant; reduced mowing frequency |
| Seville | Fine-textured; good shade tolerance |
| Bitterblue | Dense; winter color retention; better cold tolerance |
Floratam was developed in the 1970s partly for chinch bug resistance. Per Texas A&M AgriLife Extension, that resistance has broken down as southern chinch bug populations evolved. All Floratam lawns are now essentially as susceptible as older cultivars.
USDA hardiness zones
Per UF IFAS Extension, St. Augustine grass is best adapted to USDA zones 8—11. It sustains freezing damage at 25—28°F and severe damage or death below 20°F. In zone 8a and colder, winterkill is common during severe winters. Bitterblue is slightly more cold-tolerant than other cultivars.
Mowing height
Per Texas A&M AgriLife Extension, St. Augustine grass should be mowed at 2.5—4 inches. Fine-textured cultivars (Seville, Palmetto, CitraBlue): 2—3 inches. Coarser cultivars (Floratam): 3—4 inches.
Scalping below 2 inches consistently weakens the stand, reduces shade tolerance, and exposes crowns to disease and desiccation. St. Augustine grass has no rhizomes — only stolons — and once crowns are damaged, recovery is slow.
Watering
St. Augustine grass is moderately drought-tolerant but performs best with consistent moisture. Per UF IFAS Extension, established lawns require 1—1.5 inches of water per week during active growth, applied in 2 deep sessions per week rather than daily light irrigations.
Signs of drought stress appear early: blades fold lengthwise, footprints remain visible for several minutes, and color shifts to blue-gray. Per Texas A&M AgriLife Extension, watering before visible wilting begins is better than waiting for stress symptoms to develop.
Soil requirements
St. Augustine grass is best adapted to pH 6.0—7.5. It tolerates sandy soils common in coastal Florida and the Gulf Coast and adapts to moderately compacted soils. Per UF IFAS Extension, iron chlorosis (yellow leaves) is common when soil pH rises above 7.5, particularly in limestone-influenced soils in south Florida. Treat with foliar chelated iron spray; correct pH before applying lime.
Fertilization
Per Texas A&M AgriLife Extension, St. Augustine grass requires 2—4 lbs of actual nitrogen per 1,000 sq ft per year during the growing season:
| Timing | Rate (N per 1,000 sq ft) |
|---|---|
| Late April (green-up) | 0.75 lb |
| June | 0.75 lb |
| August | 0.75 lb |
In central and south Florida where growth continues year-round, a fourth application in October may be appropriate. Per UF IFAS Extension, do not fertilize St. Augustine from November through February in the Gulf Coast states — late nitrogen reduces cold hardiness.
Potassium is important for St. Augustine's stress tolerance. Per UF IFAS, use a 3-1-2 or 4-1-2 N-P-K ratio, not high-nitrogen-only products.
Pests
Southern chinch bug (Blissus insularis)
The primary insect pest of St. Augustine grass. Per UF IFAS Extension, chinch bugs suck plant sap and inject a phytotoxic saliva that kills grass. Damage appears as yellow to brown patches, usually in hot, sunny areas near pavement. Damage is often mistaken for drought.
To confirm: push a coffee can with both ends removed into the turf, fill with water, and wait 2 minutes. Chinch bugs float to the surface. Populations exceeding 20—25 per square foot warrant treatment with bifenthrin or other labeled insecticides.
Grey leaf spot (Pyricularia grisea)
Per Texas A&M AgriLife Extension, grey leaf spot is the most damaging disease of St. Augustine grass in Florida and the Gulf Coast. Water-soaked lesions with olive-gray centers appear on leaves during hot, wet conditions. Over-fertilization with nitrogen dramatically increases susceptibility. Reduce nitrogen; avoid fungicide dependence.
SAD virus (Panicum mosaic virus)
Per UF IFAS Extension, St. Augustine Decline is caused by a soilborne virus. Symptoms include mottle and chlorosis of leaves, progressive thinning, and eventual lawn loss. There is no cure. The only management is replacing Floratam with a SAD-resistant cultivar.
Common problems
| Symptom | Likely cause | Action |
|---|---|---|
| Yellow to brown patches in sunny areas | Southern chinch bug | Float test; treat if population confirmed |
| Mottled yellow leaves | SAD virus or iron chlorosis | Test for SAD; check soil pH |
| Irregular brown patches, gray water-soaked lesions | Grey leaf spot | Reduce nitrogen; no late watering |
| Slow spread or bare areas | Root damage, drought, or winter injury | Improve irrigation; overseed with plugs in summer |
Frequently asked questions
Does St. Augustine grass spread on its own? Yes, aggressively via stolons. Per UF IFAS Extension, St. Augustine can spread 6—12 inches per month during active growth in warm conditions. It will colonize garden beds and groundcover areas without physical edging.
Can I grow St. Augustine from seed? Not practically. Per Texas A&M AgriLife Extension, St. Augustine grass produces very little viable seed and must be established from sod, plugs, or sprigs. Most commercial seed labeled "St. Augustine" is either unavailable in quantity or mislabeled.
Why is my St. Augustine turning yellow? Multiple causes are possible. Per UF IFAS Extension, iron chlorosis from high soil pH is common in south Florida. SAD virus produces mottling and chlorosis with no cure. Nitrogen deficiency causes uniform light green to yellow color. Grey leaf spot causes lesions rather than whole-leaf yellowing. A soil test and visual diagnosis are needed to distinguish causes.
What is the best way to control weeds in St. Augustine grass? Dense, healthy St. Augustine crowds out most weeds naturally. Per Texas A&M AgriLife Extension, atrazine is a selective herbicide registered for use in St. Augustine grass that controls broadleaf weeds and some sedges — it cannot be used in other warm-season grasses. Always read labels; some post-emergent herbicides labeled for bermuda grass will injure or kill St. Augustine.
Sources
- UF IFAS Extension — St. Augustinegrass for Florida Lawns
- Texas A&M AgriLife Extension — St. Augustine Grass
- NC State TurfFiles — Warm-Season Lawn Grasses