September is a major fall-garden month, although northern gardens may already be nearing frost while southern gardens are entering their best planting weather. Adjust each sowing to your local first-frost date and USDA zone.

Start indoors in September

Start lettuce, spinach, kale, Asian greens, and other quick cool-season crops indoors if hot soil or pests make direct sowing unreliable. In the warmest regions, start broccoli, cabbage, and cauliflower for later fall or winter transplanting according to local timing.

Plant outdoors: cool & northern regions (zones 3–6)

In zones 3 to 6, sow fast crops such as radishes, arugula, spinach, lettuce, and baby greens under row cover if enough frost-free time remains. Harvest tender crops ahead of frost, and use low tunnels or cold frames to keep hardy greens growing longer.

Plant outdoors: warm & southern regions (zones 7–10)

In zones 7 to 10, plant cool-season vegetables broadly, including peas, carrots, beets, lettuce, spinach, brassicas, onions, radishes, and greens. Transplant fall broccoli, cabbage, cauliflower, and kale after hardening them off, while monitoring lingering heat.

Garden tasks for September

Clear spent summer crops, but leave healthy roots or add them to compost where appropriate. Refresh beds with compost, repair irrigation, and prepare frost covers or low tunnels before cold weather arrives.

Regional guidance for US home gardens; always adjust to your own last and first frost dates. Page updated Aug 4, 2026.