A warm-season month-by-month lawn care plan for St. Augustinegrass in USDA zone 9, built on soil temperature, not the calendar.
By the TurfTrigger team · Last reviewed October 10, 2026 · How our timing models work
Zone 9 times its pre-emergent off soil temperature: spring for crabgrass, fall for Poa annua. Add your ZIP and we’ll track your ZIP’s modeled soil temperature daily and email you when our model says each window opens.
Free · Zone 9 windows are typically ~mid-February and ~late October to early November.
Spring pre-emergent has to go down and be watered in before crabgrass germinates. Treat soil warming toward about 50°F as the early cue and check your ZIP's spring window; do not wait for 55°F, because crabgrass can start emerging as soil warms through that range, sometimes earlier in warm spots. ZIP soil temperatures are modeled about two inches deep and averaged over several days. Calendar dates drift year to year, so go by the soil, not the date.
Only topdress or sand-level once the lawn is in active growth: soil temperatures consistently above 65°F (closer to 75°F for sand leveling). Burying the canopy before the grass can grow through it smothers it.
USDA zone 9 encodes one thing: average annual extreme minimum winter temperature. It determines grass suitability and this schedule's broad seasonal structure, but not rainfall, summer heat, humidity, soil, or how fast your spring warms up. Your ZIP's live soil temperature and GDD accumulation determine the actual week each task lands, and that week shifts every year.
We replayed TurfTrigger's alert engine, with today's rules, on archived weather from 2019 to 2025 for a st. augustinegrass lawn in each city below. Typically the spring pre-emergent text went out first in Brandon (Jan 15) and last in Lake Charles (Feb 7). Lake Charles alone swung 24 days between its earliest and latest season, which is why the timing comes from your ZIP's soil readings and not a calendar date. The first frost typically arrives around Dec 7 in Lake Charles and Dec 10 in Tallahassee.
| City | Spring pre-emergent | First feeding | Fall pre-emergent | First frost |
|---|---|---|---|---|
| Brandon, FL | Jan 15Jan 13 to Jan 31 · 7 seasons | Mar 3Mar 3 to Mar 7 · 7 seasons | Oct 16Oct 3 to Nov 12 · 7 seasons | Jan 730-season median |
| Houston, TX | Feb 5Jan 15 to Feb 7 · 7 seasons | Mar 7Mar 3 to Mar 31 · 7 seasons | Oct 20Oct 3 to Oct 30 · 7 seasons | Dec 830-season median |
| New Orleans, LA | Feb 5Jan 16 to Feb 7 · 7 seasons | Mar 8Mar 3 to Mar 18 · 7 seasons | Oct 15Oct 4 to Nov 1 · 7 seasons | Jan 430-season median |
| Lake Charles, LA | Feb 7Jan 16 to Feb 9 · 5 seasons | Mar 16Mar 3 to Apr 1 · 5 seasons | Oct 13Oct 4 to Oct 20 · 5 seasons | Dec 730-season median |
| Tallahassee, FL | Feb 6Jan 21 to Feb 11 · 7 seasons | Mar 17Mar 3 to Apr 1 · 7 seasons | Oct 9Oct 3 to Oct 21 · 6 seasons | Dec 1030-season median |
Simulated dates from our current rules on historical modeled weather: replay results, not texts we sent and not observed crabgrass emergence. Each cell is the typical date, with the earliest and latest season under it; the season count is how many seasons that text went out. Spring and fall pre-emergent are the "apply now" texts; first feeding is the first nitrogen text of the year. First frost is the median date the modeled air temperature first reached 36°F in fall over the previous 30 seasons. Replays use modeled weather for each city's grid cell, not a weather station, and substitute what actually happened for the forecast a real lawn would have seen.
A one-page, fridge-ready version of this St. Augustinegrass zone 9 schedule. Free, no signup.
Download PDFAffiliate disclosure: as an Amazon Associate, TurfTrigger earns from qualifying purchases made through the links below, at no extra cost to you. Picks are product categories, not endorsements of a specific brand. Always follow the product label.
St. Augustinegrass is a warm-season grass, and this schedule is tuned for USDA hardiness zone 9. It breaks dormancy and greens up once soil temperatures hold near 65°F, which is the anchor for the season's first feeding and weed-control timing. Southern zones. Extremely sensitive to certain herbicides; ensure strict database checks against grass_safety schemas.
Warm-season grass in USDA zone 9. Highly sensitive to heat-stress herbicides and mechanical damage (no verticutting). Potassium is critical for winter stolon survival.
Each of our 48 grass-and-zone schedules is generated from a per-grass agronomic profile (green-up soil temperature, mowing heights, annual nitrogen budget, disease pressure) assembled from published university-extension turf guidance, then sequenced for zone 9's season length. Timing anchors follow the same soil-temperature and growing-degree-day models our live app runs, documented on the methodology page. Key public models: MSU's GDDTracker (crabgrass GDD, Calhoun 2004) and Purdue Turf Science (broadleaf timing, Schleicher 1995).
Limitations: this is general guidance for typical st. augustinegrass lawns in zone 9, not a reading of your yard. Microclimate, soil, and each spring's weather shift the real windows by weeks, which is why the exact weeks come from live soil data, not this calendar. And the product label always wins: follow the label's rates, restrictions, and safety directions over anything here.
Apply spring pre-emergent before crabgrass germinates: check your ZIP's spring window as soil warms toward 50°F, and do not wait for 55°F. In zone 9 that is usually early-to-mid spring, but the exact week shifts every year. Track soil temperature, not the calendar.
Keep St. Augustinegrass around 2.5–3.5″ in spring and fall, raising to about 3–4″ through summer heat. Never remove more than one-third of the blade in a single mow.
St. Augustinegrass wants roughly 2–4 lbs of nitrogen per 1,000 sq ft per year. Wait until complete green-up and 65°F soil temperatures. Feed throughout peak summer growth. Cease nitrogen applications in fall.
The signature disease is Take-All Root Rot, triggered by high rainfall and stressed roots. Catching the conditions early is far easier than curing an outbreak.
Yes, zone 9 is within St. Augustinegrass's recommended range. St. Augustinegrass is a warm-season grass. It needs mild winters (zones 8–10) and won't survive hard freezes up north.