Monthly checklist · early fall
Houseplant Care in September
September is the handoff month. Outdoor plants come in, watering schedules taper, and the year’s last new growth happens.
Quick answer
Bring all outdoor plants inside before night temps hit 50°F. Quarantine 2 weeks. Reduce fertilizer to half strength.
Light in September
Daylight hours drop noticeably. Most species adjust on their own; some (calathea, anthurium) protest with leaf droop. Move them closer to windows.
Watering in September
Cut frequency 15–25% from peak summer. Confirm with finger test — cooler indoor temps mean slower drying.
Pests and problems to watch in September
Returning outdoor plants are the #1 pest vector of the year. Inspect under leaves, in soil, and along stems for spider mites, scale, and mealybugs.
What to plan now
Stock up on insecticidal soap and neem oil before winter problems show up.