St. Augustine Grass Lawn Care Schedule: Month-by-Month Southern Lawn Guide
St. Augustine is the defining lawn grass of the Gulf Coast — from the Florida Panhandle through coastal Texas. Nothing else handles the combination of heat, humidity, and shade that comes with a Southern yard quite as well. Its wide, coarse blades spread quickly from plugs or sod, and it's the only warm-season grass that genuinely thrives under a tree canopy.
But St. Augustine has specific requirements that catch homeowners off guard: it mows high, it needs consistent moisture, it's vulnerable to chinch bugs, and it responds badly to cold. Get those four things right and it's a reliable, low-stress lawn.
The St. Augustine Calendar at a Glance
| Month | Key Actions | Priority |
|---|---|---|
| January | Dormant in Zone 8–9; semi-active in Zone 10 — no feeding | Low |
| February | Apply pre-emergent as soil approaches 55°F | High |
| March | Watch for green-up; resume mowing | Medium |
| April | First fertilization after full green-up; post-emergent for weeds | High |
| May | Peak growth — fertilize, water consistently, mow every 7–10 days | High |
| June | Continue fertilization; begin chinch bug monitoring | High |
| July | Peak heat — water 1–1.5 inches per week; watch for fungal disease | High |
| August | Last summer fertilization; monitor large patch and gray leaf spot | Medium |
| September | Taper nitrogen; iron supplement if yellowing | Medium |
| October | Grass slows; final mow; no more fertilization | Low |
| November | Dormant in Zone 8–9; reduce watering | Low |
| December | Dormant — no action needed | — |
Mowing Height: Higher Than You Think
St. Augustine's most important care rule: keep it high. The recommended height is 3.5–4 inches for standard varieties — significantly higher than Bermuda (1–2 inches) or even tall fescue (3–4 inches).
Why so high? St. Augustine's wide blades need canopy to photosynthesize effectively. Scalp it below 3 inches and you remove the green leaf tissue entirely, leaving behind pale yellow stolons. Recovery is slow, and a scalped lawn is more vulnerable to chinch bugs, disease, and weed invasion.
Some dwarf varieties (Seville, Delmar) tolerate 2–2.5 inches — check your variety before lowering the deck.
Frequency: Every 7–10 days during active growth; less often as growth slows in fall.
Fertilization: Spring Through Summer, Nothing in Fall
St. Augustine is a moderate-to-heavy feeder that responds well to a consistent spring-through-summer schedule.
A practical schedule:
- April: 1 lb N/1,000 sq ft after full green-up
- June: 1 lb N/1,000 sq ft
- August: Last summer feeding — 0.75–1 lb N/1,000 sq ft
Stop fertilizing by September in Zone 8–9 (coastal Texas, Mississippi, Alabama). In Zone 9–10 (South Florida), a light application in October is acceptable.
Cold damage to tender growth is a real risk with St. Augustine. Unlike Bermuda, which tolerates cold injury reasonably well, St. Augustine can suffer significant dieback — and late-season nitrogen stimulates exactly the tender growth that's most vulnerable.
Iron: The Often-Missed Nutrient
St. Augustine frequently shows yellowing between leaf veins (interveinal chlorosis) in alkaline or sandy soils. This is iron deficiency, not nitrogen deficiency — and adding more nitrogen to fix it is a common mistake that makes the problem worse.
If your lawn looks yellow despite regular fertilization, test soil pH. If it's above 7.0, apply chelated iron or a soil acidifier. A single iron application typically greens the lawn within 1–2 weeks.
Chinch Bugs: The #1 Threat
St. Augustine's most dangerous pest is the chinch bug — a small insect that sucks sap from grass blades while injecting a toxin that blocks water uptake. Damage appears as irregular yellow patches in sunny areas, then turns brown as the grass dies.
When to watch: June through August, during hot and dry conditions.
How to detect: Push a metal can with the bottom removed into the turf at the edge of a yellow area. Fill with water and wait 5 minutes. Chinch bugs float to the surface if present.
Treatment: Apply bifenthrin or lambda-cyhalothrin in early June as a preventative in lawns with a history of chinch bugs. If damage has already appeared, treat immediately — chinch bugs spread fast.
Consistent irrigation significantly reduces chinch bug pressure. Dry, stressed St. Augustine is far more vulnerable than well-watered turf.
Watering: Consistent Moisture Matters
St. Augustine is less drought-tolerant than Bermuda or Zoysia. Signs of drought stress: leaves fold lengthwise and the turf takes on a blue-green tinge. Water immediately when you see this — don't wait for browning.
Target: 1–1.5 inches per week in two or three deep sessions. Sandy soils (especially in Florida) may need more frequent irrigation to maintain moisture in the root zone.
Common Problems
Chinch bugs (June–August) are the most damaging and common pest. Monitor regularly in sunny areas.
Take-All Root Rot causes yellowing and thinning from a soil-borne fungus in wet, compacted conditions. Improve drainage and reduce irrigation.
Gray Leaf Spot produces gray-to-tan lesions during hot, humid summer weather. Avoid high nitrogen in summer and water in the morning only.
St. Augustine Decline (SAD) is a viral disease causing permanent yellowing with no cure. Remove affected areas and replant with a resistant variety — Floratam is the most widely available.
Get a free St. Augustine schedule with chinch bug alerts and fertilization reminders timed to your Gulf Coast zone.