September garden tasks: Northeast and Long Island
September is my favorite month in the garden. The temperature drops below 75°F consistently, the Japanese beetles are gone, the humidity breaks, and the garden is actually pleasant to work in again. At my Long Island house, September brings the phlox and sedum into bloom, the hydrangea panicles.
September is my favorite month in the garden. The temperature drops below 75°F consistently, the Japanese beetles are gone, the humidity breaks, and the garden is actually pleasant to work in again. At my Long Island house, September brings the phlox and sedum into bloom, the hydrangea panicles transition from cream to dusty pink, and the fall planting list is actually manageable.
The average first frost in zone 7 (Long Island, NYC metro) is November 7. That means September has a full 8—10 weeks of productive growing ahead. In zone 5 (upstate NY, Vermont, NH), first frost averages October 1—7 — September is the last productive month, and every week matters.
This article contains affiliate links. As an Amazon Associate, we earn from qualifying purchases - at no extra cost to you. We only recommend products we have personally tested or that are the universal first recommendation from university Extension publications. See our full disclosure.
Fall vegetable planting and harvest
Per Cornell Cooperative Extension, September vegetable tasks:
Zone 7 (Long Island, NYC area):
- Direct sow spinach, kale, arugula, and lettuce September 1—15 for November harvest
- Set out broccoli and cabbage transplants started in July—August
- Garlic planting window opens in October; order seed garlic now for delivery
Zone 6 (coastal CT, inland NJ, Hudson Valley):
- Direct sow spinach and kale September 1 for October—November harvest
- Broccoli transplants must be in by September 1—7 to make head size before frost
Zone 5 (upstate NY, Vermont, NH, zone 5 MA):
- Fall vegetables are limited; spinach and kale started in August can still be harvested; add floating row cover to extend season
- Per UMass Extension, floating row cover (2 oz/yd) provides approximately 6°F of frost protection and extends the zone 5 harvest season 3—4 weeks
Harvesting before frost:
- Green tomatoes left on the vine will not ripen before frost; at first frost warning, harvest all tomatoes; green tomatoes ripen at room temperature over 2—4 weeks
- Winter squash and pumpkins: harvest before hard frost; skin should resist a fingernail; leave 2-inch stem attached; cure at 70—80°F for 10 days before storage