In October, St. Augustine is slowing down in the Gulf Coast & Florida and going dormant in the transition zone — soil around 60–72°F, and the soil cooling. The jobs that matter most: mow on a routine and fall pre-emergent for winter weeds. Skip nitrogen and aeration.
| Region | Growth | Mow | Water |
|---|---|---|---|
| South USDA 9+ | slowing ~72°F soil, cooling | 3.5–4" every 7-10 days | Water on demand now, not on a schedule — the lawn's use drops with the soil temperature. Irrigate when the leaf blades fold in half lengthwise, the colour goes blue-grey, or footprints stay visible after you walk across it. Put down 1/2 to 3/4 in when you do, about once a week or less; UF/IFAS puts the cooler months at one watering day a week. Before sunrise, so the blades dry as the sun comes up. |
| Transition USDA 7–8 | going dormant ~60°F soil, cooling | 2.5–3" every 7-10 days | Taper off. Cut back to roughly half the growing-season figure and stop irrigating as growth stops. Going into winter wet invites disease and, on warm-season turf, soft growth that freezes. |
Growth status, soil temperature and the mow and water guidance are derived from each zone's soil curve together with St. Augustine's own dormancy and green-up thresholds, so each row describes that region rather than an average of all of them.
The Gulf Coast, Florida, south Texas and the desert Southwest. The longest growing season of the three, and the only one where many warm-season lawns barely go dormant at all.
Mowing note: Cultivar matters as much as zone: Floratam, BitterBlue and Classic run 3.5-4 in; Palmetto and Raleigh 3-4 in; CitraBlue 2-3 in; the dwarfs (Seville, Captiva, Delmar) at 2-2.5 in.
A warm-season lawn grown at a consistent height and cut often enough to never lose a third of its blade is the cheapest weed control there is — a dense canopy leaves weed seed nowhere to germinate.
Adequate potassium supports winter hardiness and disease resistance, which is why the application is gated on a soil test rather than recommended to everyone. Clemson: "may be applied to enhance winter hardiness if a recent soil test indicates low to medium levels of potassium." UF/IFAS puts the same thing the other way round — potassium "should be maintained at adequate levels", and the programme "should be based on a recent soil test". If your test says the level is already adequate, adding more does not buy you extra hardiness.
Clemson Cooperative Extension, St. Augustinegrass Yearly Maintenance Program (HGIC 1218) · UF/IFAS, SL21/LH014 — General Recommendations for Fertilization of Turfgrasses on Florida Soils
Full fertilizer guide →Poa annua, henbit and chickweed germinate in autumn as the soil falls back through the high 60s. Catching them now is the difference between a clean lawn in February and spending February spraying — and by February the only option left is post-emergent on a dormant lawn.
NC State Extension, Carolina Lawns — pre-emergent timing · Texas A&M AgriLife Extension, L-5340 — Lawn Care
Full weed-control guide →St. Augustine and centipede are injured by the 2,4-D products that are safe on bermuda, and the damage often shows up a week later as yellowing that looks like disease. Celsius WG is the first choice because it is labeled for both and holds up in heat better than the alternatives.
Texas A&M AgriLife Extension, EHT-144 — St. Augustinegrass · Texas A&M AgriLife Extension, L-5340 — Lawn Care
Full weed-control guide →Large patch infects in autumn as soil temperatures fall, but the circular dead patches do not appear until spring — so the only useful treatment is a preventive one applied now. Treating in spring, when you can see it, is treating damage that is already done. NC State: "For centipedegrass and St. Augustinegrass, applications should be initiated when soil temperatures decline to 80 F for 5 or more consecutive days." Centipede is the most susceptible turfgrass there is to this disease.
UF/IFAS, SS-PLP-5/LH044 — Large Patch · NC State Extension, Large Patch in Turf
Full disease guide →The band from the Carolinas across to Oklahoma and up through the lower Midwest, where both warm- and cool-season grasses are grown and neither is entirely comfortable. Timing here runs three to five weeks behind the south.
Mowing note: Cultivar matters as much as zone: Floratam, BitterBlue and Classic run 3.5-4 in; Palmetto and Raleigh 3-4 in; CitraBlue 2-3 in; the dwarfs (Seville, Captiva, Delmar) at 2-2.5 in.
Going into winter at the right height matters: too long and the canopy mats down and holds moisture against the crowns, which is how large patch and snow-related rots start. Too short and the crowns have no insulation.
UF/IFAS, ENH5/LH010 — St. Augustinegrass for Florida Lawns
Full mowing guide →In the Gulf Coast & Florida, no. Nitrogen — work back from your own first-frost date, not the calendar. The cutoff is about six weeks before your average first frost, which is late October on the upper Gulf and in north Florida, and later again further south. UF/IFAS puts the last feed in the middle or end of September in north Florida and early October in central Florida; in south Florida, which rarely freezes, it can be applied year-round as needed. In the transition zone, no. Nitrogen — too late in the year. Late nitrogen pushes soft growth that freeze damage takes first.
In the Gulf Coast & Florida, no — soil is around 72°F at 4-inch depth and cooling. In the transition zone, not yet, but it is going dormant — soil is around 60°F at 4-inch depth and cooling. St. Augustine goes dormant below about 55°F soil temperature and greens up again around 65°F. Take the reading at 4 inches, in a sunny representative part of the lawn, in the morning.
In the Gulf Coast & Florida, 3.5–4 inches, every 7-10 days. Cultivar matters as much as zone: Floratam, BitterBlue and Classic run 3.5-4 in; Palmetto and Raleigh 3-4 in; CitraBlue 2-3 in; the dwarfs (Seville, Captiva, Delmar) at 2-2.5 in. In the transition zone, 2.5–3 inches, every 7-10 days. Cultivar matters as much as zone: Floratam, BitterBlue and Classic run 3.5-4 in; Palmetto and Raleigh 3-4 in; CitraBlue 2-3 in; the dwarfs (Seville, Captiva, Delmar) at 2-2.5 in.
In the Gulf Coast & Florida: Water on demand now, not on a schedule — the lawn's use drops with the soil temperature. Irrigate when the leaf blades fold in half lengthwise, the colour goes blue-grey, or footprints stay visible after you walk across it. Put down 1/2 to 3/4 in when you do, about once a week or less; UF/IFAS puts the cooler months at one watering day a week. Before sunrise, so the blades dry as the sun comes up. In the transition zone: Taper off. Cut back to roughly half the growing-season figure and stop irrigating as growth stops. Going into winter wet invites disease and, on warm-season turf, soft growth that freezes.
Fall pre-emergent for winter weeds. When: as the 7-day mean soil temp falls through 67-70 F at 4 in. Temperature: do not apply above 90°F. CHECK THE LABEL LISTS YOUR GRASS. Not every pre-emergent is labeled for St. Augustine or centipede, and the ones that are often carry a lower rate for them than for bermuda — on those two grasses, a product whose label does not name your grass is a product that can thin it. Purdue AY-10 also lists pendimethalin, oxadiazon and benefin; residual runs 60-120 days depending on rate. Spot-treat broadleaf weeds — sensitive grass. When: on an actively growing lawn, on a sunny day above 55 F and below the 85 F ceiling. Temperature: apply on a day above 55°F and below 85°F. Atrazine is NOT a safe substitute: Texas A&M EHT-144 says Floratam is not tolerant of it, and Floratam is the most common St. Augustine cultivar.
Soil temperatures are Lawn HQ estimates for your climate zone. How we work
By Lawn HQ · Last reviewed . Extension or land-grant sources only, matched to this grass and this climate zone. Found something wrong? Tell us and we will fix it and update the date.
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