What to Do in the Garden in September (Warm-Climate US)

Plant and sow

• Set out broccoli, cabbage, cauliflower, and collard transplants; shade them for the first week if heat lingers.
• Direct-sow carrots, beets, turnips, radishes, lettuce, spinach, and mustard as temperatures ease.
• Establish strawberry plants — fall planting, spring harvest is the southern pattern (UF/IFAS September task).
• Desert Southwest: peak fall vegetable planting month per the Maricopa County calendar.
• Refresh tired summer beds with ageratum, celosia, zinnia, and marigold for fall color.

Maintain and protect

• Apply the year's final lawn fertilizer mid-to-late month; choose a low- or no-phosphorus product (UF/IFAS).
• Fertilize citrus with a balanced product as fruit sizes up (Central Florida calendar).
• Water new fall transplants consistently — September heat can still kill seedlings in days.
• Watch lawns for fall armyworm damage and treat per current extension guidance.
• Keep fall tomatoes staked, watered, and scouted for hornworms.

Harvest

• Keep picking okra, peppers, eggplant, and southern peas — often their best month of the year.
• Harvest fall-crop beans, cucumbers, and squash from August sowings.
• Cut pumpkins and winter squash as rinds harden ahead of October.

Sources

Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.

• UF/IFAS Extension — North Florida Gardening Calendar (EP451) — September: establish strawberries and cool-season vegetables; apply final lawn fertilizer mid-to-late month with little or no phosphorus
• UF/IFAS Extension — Central Florida Gardening Calendar (EP450) — September citrus task: fertilize with balanced fertilizer; cool-season vegetable window opens
• University of Arizona Cooperative Extension — Vegetable Planting Calendar for Maricopa County (AZ1005) — Fall is one of the low desert's two optimal planting seasons, with many vegetables planted in September

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