When to Plant Onions in Vermont
The backbone of the kitchen garden. Choose short-day, intermediate, or long-day varieties based on your latitude.
The Short Answer
Vermont Frost Dates
Your planting dates depend on which part of Vermont you're in. Here are the frost date ranges by region:
| Region | Zones | Last Frost (Spring) | First Frost (Fall) |
|---|---|---|---|
| Northern Vermont | 3b, 4a | May 20 - Jun 5 | Sep 5 - Sep 20 |
| Central Vermont | 4a, 4b, 5a | May 10 - May 25 | Sep 15 - Oct 1 |
| Southern Vermont | 4b, 5a, 5b | May 5 - May 20 | Sep 20 - Oct 5 |
Onions Planting Schedule for Vermont
Northern Vermont (Zones 3b, 4a)
Average last frost: May 20 - Jun 5 · Average first frost: Sep 5 - Sep 20
Central Vermont (Zones 4a, 4b, 5a)
Average last frost: May 10 - May 25 · Average first frost: Sep 15 - Oct 1
Southern Vermont (Zones 4b, 5a, 5b)
Average last frost: May 5 - May 20 · Average first frost: Sep 20 - Oct 5
Growing Onions in Vermont
Onions in Vermont's Climate
You're in long-day onion territory — plant varieties that bulb when days exceed 14-16 hours. This means Copra, Walla Walla, and Yellow Globe Danvers. Plant sets or transplants from mid-April. The critical distinction: short-day onions from southern catalogs will NOT form bulbs in your zone because your long summer days trigger bulbing too early, before the plant is large enough.
Soil Considerations for Vermont
Rocky, acidic soils typical of New England. Glacial deposits. Thin mountain soils. Raised beds very popular. Loose, well-drained soil is especially important for onions since the edible portion grows underground. If your soil is heavy clay, consider raised beds.
Vermont Climate & Growing Season
Short growing season. Cold winters. Cool summers. Long summer days help compensate. Season extension techniques valuable. Onions can handle frost well, which is an advantage in Vermont's climate. You can push planting dates earlier in spring and extend into fall.
Growing season length varies across Vermont: Northern Vermont (3b, 4a) has a last frost around May 20 - Jun 5, while Southern Vermont (4b, 5a, 5b) sees frost end around May 5 - May 20. This difference matters for onions — but onions handle frost well, so the timing difference is less critical.
Growing Tips
Day length triggers bulbing. Northern gardeners need long-day varieties. Southern gardeners need short-day varieties.
Companion Planting
Plant onions alongside these companions for better growth:
Keep onions away from:
The Bottom Line
Last reviewed: March 29, 2026