September · USDA Zone 9
autumnWhat to plant in September in USDA zone 9
Autumn planting guide for zone 9 (Central + South Florida, Southern Texas, Southern California, Arizona) — a 280-day growing season with last frost around mid-February to early March and first frost around late November / early December.
Sow outdoors in September — zone 9
Direct-sow these seeds into prepared garden beds or large containers. Soil temperature matters more than the calendar date — wait for a sustained warm-up before sowing tender crops.
Transplant in September — zone 9
Move hardened-off seedlings into the garden. Tender crops want soil above 16 °C and night temperatures consistently above 10 °C; cool-season transplants tolerate light frost.
- Fall tomato, pepper, and brassica transplants
Harvest in September — zone 9
These crops should be ready or in active harvest in September for zone 9 gardens. Pick fruiting crops every 2-3 days to keep production going.
- Sweet potatoes, okra, southern peas, hot peppers, citrus (early)
Prep and planning — zone 9
- Plant garlic by mid-October — order now
Universal September tasks
These apply across most US and UK gardens in September, regardless of zone.
- Plant garlic (zones 3-5 — start of the window).
- Sow autumn salad, spinach, lettuce, radishes, and mache.
- Transplant fall brassicas if not done in August.
- Sow cover crops (winter rye, vetch, clover) on empty beds.
- Harvest and cure winter squash, pumpkins, and onions.
- Start collecting and saving heirloom seed from open-pollinated favorites.
Why this works for zone 9
Zone 9 has average annual minimum temperatures of 20 to 30°F (-7 to -1°C) and a frost-free window from mid-February to early March to late November / early December — about 280 growing days. Heat-tolerant tomato varieties (Solar Fire, Heatwave II) needed for midsummer. Cool-season crops grow Oct-Apr while northern zones are dormant.
Dates are zone-wide averages. Local microclimates (south-facing slopes, urban heat, lakeside warmth, elevation) can shift the window by 1-2 weeks within the same zone.
UK gardeners — September
September starts the UK's autumn garden. Sow winter salad, spring cabbage, mustard, mizuna, and overwintering onions. Plant garlic and overwintering broad beans late month. Harvest apples, pears, plums, sweetcorn, and main-crop potatoes.
Source and methodology
Frost-date averages from NOAA Climate Data Online within USDA zone 9. Hardiness boundaries from the USDA Plant Hardiness Zone Map (2023). Crop timing curated against US Cooperative Extension Service publications (UNL, UMN, NC State, Texas A&M, UF/IFAS, Oregon State) and cross-referenced against the RHS sowing calendar. Curated by the Growli editorial team.
Keep going
- ← August in zone 9
- October in zone 9 →
- All zones — what to plant in September
- USDA Zone 9 — frost dates and crop list
- Full 12-month planting calendar