September · month 9 of 12
What to do in the garden in September
Every job worth doing in September, built from the real care schedules of the plants gardeners grow — with the exact plants that need each one.
Plant in September
Plant starts in spring or sow seeds in late summer for next year's bloom
Prune in September
Cut spent flower stalks back to the ground after blooming.
Divide in September
Divide clumps in early fall every 3-4 years if needed.
Fertilize in September
Feed with a balanced liquid fertilizer every 4-6 weeks.
Deadhead in September
Remove spent flowers for tidiness, but leave some cones for winter interest.
Check for Pests in September
Check for yellow oleander aphids; wash off with a strong spray of water.
Stake in September
Provide support for tall stems before they begin to flower, if needed.
Propagate in September
Collect seeds from dried pods for next year's planting or allow to self-seed.
Harvest in September
Harvest flowers when fully open for cutting.
Lift & Store in September
Cure harvested potatoes in a dark, airy place for 1-2 weeks before storing.
What's blooming in September
In flower around now.
Frost dates and bloom windows are typical ranges, not guarantees — your microclimate moves them by weeks. Sow uses your real local forecast instead.
September questions
What should I do in the garden in September?
The jobs that matter most this month are plant, prune, divide, fertilize. Each section above lists the specific plants that need that job in September — drawn from the care schedules of the plants gardeners actually grow.
Does this calendar change by hardiness zone?
The tasks are the same, but which plants you can grow is not. Pick your zone below to see this month's jobs filtered to plants that survive your winters.
What's blooming in September?
Cheyenne Spirit Coneflower, Pink Muhly Grass, Walker's Low Catmint, American Gold Rush Black-eyed Susan, Purple Dome New England Aster and others are in flower around now. The full list is above.
Keep exploring
Get September's tasks for your own plants
Sow builds this checklist from the plants actually in your yard — and adjusts it to your real forecast, so a wet week skips the watering and a frost warning reaches you first.