What to Plant in September in Zone 3: Last Call Before Frost
In USDA zone 3, September is last call for most crops and the month to plant garlic. Fast radishes or arugula may still fit. Then cover crops.
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September Zone 3 September zone 3 fall planting
What to Plant in September in Zone 3
In USDA zone 3, September is last-call, not a planting month. First frost often arrives in September in many zone 3 gardens, but yards vary. Most long-season fall crops are too late from seed. Fast radishes, arugula, spinach, or lettuce may still finish if the catalog window is open and frost settings allow. Then sow cover crops on spent beds. Do not start tomatoes, peppers, or melons. Plant garlic from about September 15 to 29.
Use My Garden frost settings or the zone 3 fall calendar and count backward. See What to plant now and warmer September zone 6 timing for contrast.
Sow These Only If Frost Allows
- Radishes and arugula: short crops. Catalog fall windows run about August 15 to September 30. Confirm several weeks remain before a hard freeze. Fall radishes, fall arugula.
- Spinach and lettuce: late from seed. Only if frost settings still show an open window. Fall spinach, fall lettuce.
- Kale, broccoli, cabbage: too late to seed for a fall head. Harvest what you transplanted earlier, or grow fast greens instead. Fall kale, fall broccoli, fall cabbage.
Cover Crops on Spent Beds
If a bed will not hold a short green crop, sow winter rye now. It can go in until about 2 weeks after first frost, near September 29 at zone defaults. Oats need 6 weeks before first frost, so they are past. When to sow cover crops by zone.
Plant Garlic Mid to Late September
Plant garlic from about September 15 to 29 in zone 3, within two weeks after your first frost. Set cloves pointed end up, 2 inches deep and 4 to 6 inches apart. Once the soil cools, cover the bed with 3 to 4 inches of straw. Spring-planted garlic gives small bulbs here. Use the Garlic Desk with your own frost date and see garlic by zone.
Next Steps
Check frost settings today. If weeks remain, sow a short row of radishes or arugula. Clear one spent bed for cover crop. Get garlic in the ground in the second half of the month.