Stenotaphrum secundatum
Warm-season grassUSDA zones 8–10Broad-bladed and shade-tolerant. Popular in Gulf Coast states. St. Augustinegrass is a warm-season grass: it grows hardest in summer heat, slows as nights cool in fall, and goes dormant and tan after the first frost until spring green-up.
| Season | Mowing height |
|---|---|
| Spring | 2.5–3.5 in |
| Summer | 3–4 in |
| Fall | 3–4 in |
Follow the one-third rule: never remove more than a third of the blade in one cut. At a 4-inch summer height, mow before the lawn passes about 6 inches. In summer peak growth that means about every four to six days.
| # | When | Nitrogen per 1,000 sq ft | Fertilizer | Notes |
|---|---|---|---|---|
| 1 | Late spring (full green-up, soil >65F) | 0.5–1 lb | 16-4-8 | After dormancy exit is confirmed: first feeding of the season |
| 2 | Early summer (June) | 1 lb | 20-0-10 or 3-1-2 | Peak growing season begins: primary nitrogen application |
| 3 | Mid-summer (July) | 0.5–1 lb | 15-0-15 | Maintain growth plus potassium for stress tolerance |
| 4 | Late summer (August) | 0.5–1 lb | 3-1-2 | Optional: for high-maintenance / showpiece lawns only |
| 5 | Early fall (September-October) | 0.5 lb | High-K (e.g. 0-0-20) | Winterizer: apply 4-6 weeks before first expected frost |
Feed St. Augustinegrass while it's actively growing, from green-up through late summer, and stop well before dormancy. Don't apply more than 1 lb of quick-release nitrogen per 1,000 sq ft at once, and follow a soil test for phosphorus and lime.
St. Augustinegrass uses water at about 65% of your area's reference evaporation rate. In summer that usually works out to 1 to 1.5 inches a week from rain and watering combined, less in cool weather. Water deeply and infrequently, once or twice a week before 10 AM, rather than a little every day: deep soaks grow deep roots.
St. Augustinegrass tolerates drought better than cool-season grass and will go dormant rather than die in a long dry spell.
Pre-emergent crabgrass preventer only works if it's down before the seeds germinate. The most reliable timing is by accumulated warmth: apply between 250 and 500 growing degree days (base 32F) since January 1. How to time crabgrass preventer explains the method and shows when the window opened in five cities in 2026.
Core aerate in early summer, about five weeks after your last spring frost, when St. Augustinegrass is growing hard enough to heal the holes within a few weeks. Aerate when the soil is moist; tines can't get into dry, hard ground.
St. Augustinegrass fills in by spreading (runners and rhizomes), so thin areas recover from the lawn itself rather than overseeding.
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2.5–3.5 inches in spring, 3–4 inches in summer, and 3–4 inches in fall. Never remove more than a third of the blade in one cut.
Late spring (full green-up, soil >65F), early summer (June), mid-summer (July), late summer (August), and early fall (September-October).
When 250 to 500 growing degree days (base 32F) have built up since January 1, before crabgrass germinates. That ranged from mid-January in Oklahoma City to mid-April in Ottawa in 2026.