September garden tasks: Southeast

September in the Southeast is a reset. Temperatures drop below 90°F consistently, humidity decreases, and the garden becomes a pleasure to work in again after the brutal July--August pause. This is also when the fall garden window opens for real -- September is one of the two best planting months.

September in the Southeast is a reset. Temperatures drop below 90°F consistently, humidity decreases, and the garden becomes a pleasure to work in again after the brutal July—August pause. This is also when the fall garden window opens for real — September is one of the two best planting months (along with spring) in the Southeast.

Per Clemson HGIC, average September temperatures: Columbia SC high 83°F, Atlanta 81°F, Charlotte 78°F. Overnight lows in September drop into the 60s in zone 7b—8, providing the cool nights that make fall vegetables exceptional.

Fall vegetable planting

Per NC State Extension, September planting priorities for the Southeast:

Direct sow immediately (September 1—15):

• Spinach: the first spinach planting of fall; sow thickly for baby spinach harvest in 5—6 weeks; per NC State, spinach needs soil temperature below 85°F for reliable germination — the cooling September nights in zone 7b—8 bring it into range
• Arugula: fastest cool-season crop (30—35 days); sow September 1 for early October harvest; tolerates some frost, extending the harvest well into November
• Lettuce: sow every 2 weeks September 1—October 1 for continuous harvest through November; use heat-tolerant batavian types in early September when daytime temperatures are still 80°F+
• Radishes: 25-day crop; sow September 1—October 15 in zone 8
• Kale, collards, mustard: sow or transplant for fall harvest through December in zones 8—9; per NC State, kale flavor improves significantly after the first frost
• Turnips: direct sow through September; one of the most productive fall crops in the Southeast; both roots and greens are edible

Transplant:

• Broccoli, cabbage, cauliflower: if started in July, transplants should be ready for setting out September 1—15 in zone 8; these are the most rewarding fall crops in the Southeast — fall broccoli consistently outperforms spring broccoli in quality
• Onion plants: per Clemson HGIC, September—October is the planting window for short-day onion varieties (the type suited to zones 7—9); long-day varieties planted in fall bolt before bulbing

Zone 9 (Gulf Coast, central Florida): Per UF IFAS Extension, in zone 9—10 the fall vegetable garden opens with direct seeding of tomatoes (September 1—15) and transplanting of tomatoes and peppers for the best production season (October—November in zone 10).