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.
- Growth
- slowing~72°F soil, cooling
- Mow
- 1–2"weekly
- Water
- 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.
Do thisEvery week this month
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.
When: throughout the month
Steps
- Cut on a schedule, not when the lawn looks long.
- Never remove more than a third of the blade in one pass.
- Change direction each time so the grass does not learn a lean.
- Re-sharpen the blade every 20-25 hours of cutting.
If you have time
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.
When: 4 to 6 weeks before the first expected frost, and only on a soil test showing low or medium potassium
Rate: 1 lb K2O per 1,000 sq ft — 1.6 lb of 0-0-60, or 2 lb of 0-0-50
Product: 0-0-60 analysis, potassium-only fertilizer: muriate of potash (0-0-60) or potassium sulfate (0-0-50)
Label: Nitrogen-free. Clemson's bermuda, zoysia and St. Augustine programmes all name these two analyses for the fall potassium application; a nitrogen-bearing blend such as 15-0-15 is NOT a substitute this late in the year.
Steps
- Start with the soil test. No test, or a test showing potassium is already adequate: skip this task — it is not a mild benefit, it is no benefit.
- Low or medium potassium on a recent test: this is the application.
- Target 1 lb of actual potash (K2O) per 1,000 sq ft.
- Use either 1.6 lb of muriate of potash (0-0-60) or 2 lb of potassium sulfate (0-0-50) per 1,000 sq ft — both deliver that 1 lb of K2O.
- Get it down 4 to 6 weeks before your average first frost.
- Do NOT substitute a fertilizer that carries nitrogen. A 15-0-15 delivers N you are past the cutoff for, and that is the opposite of winter hardening.
- Apply to dry grass and water in.
Do this
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.
When: as the 7-day mean soil temp falls through 67-70 F at 4 in (week 1 of the month)
Rate: per label for your grass and your square footage; if you are planning a second application, the label's ANNUAL maximum is the number that governs
Product: pre-emergent herbicide, active ingredient prodiamine or dithiopyr, per label
Label: 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.
Soil temperature: 67–70°F soil at 4-inch depth.
Air temperature: Do not apply above 90°F air temperature — above that you risk injuring the lawn.
Steps
- Go by falling soil temperature: apply as the 7-day mean drops through 67-70 F at 4 in.
- Water in with half an inch within 24 hours.
- Do not aerate after applying.
- One application usually holds the winter. A second at half rate 8-10 weeks later extends it ONLY IF THE LABEL ALLOWS a sequential application and you stay inside its annual maximum — check before you buy, not after you have applied the first one.
NC State Extension, Carolina Lawns — pre-emergent timing · Texas A&M AgriLife Extension, L-5340 — Lawn Care
Full weed-control guide →Worth doing
Spot-spraying a few weeds puts a fraction of the chemical on the lawn that a blanket application does, and it works better — you are treating the weed, not the turf around it.
When: on an actively growing lawn, on a sunny day above 55 F and below 90 F
Product: selective post-emergent broadleaf herbicide
Label: Read the label for your grass — tolerance differs by species and by cultivar.
Air temperature: Spray on a day above 55°F; not above 90°F. Below the floor the weed is not actively growing and the application is wasted; above the ceiling you injure the lawn.
Steps
- Spray the weed, not the lawn. A hand sprayer beats a hose-end attachment for this.
- Mow 2-3 days BEFORE spraying, not after — the herbicide needs leaf area to be absorbed through.
- Wait until temperatures are below the ceiling. Heat turns a selective herbicide into a non-selective one.
- There is a floor as well as a ceiling: spray on a sunny day with the high above 55 F. Below that the weeds are not actively growing and nothing moves into the root.
- Do not spray a drought-stressed lawn, and do not spray newly laid sod.