When to Plant Onions in Massachusetts
The backbone of the kitchen garden. Choose short-day, intermediate, or long-day varieties based on your latitude.
The Short Answer
Massachusetts Frost Dates
Your planting dates depend on which part of Massachusetts you're in. Here are the frost date ranges by region:
| Region | Zones | Last Frost (Spring) | First Frost (Fall) |
|---|---|---|---|
| Western Massachusetts | 5b, 6a | May 1 - May 20 | Sep 20 - Oct 10 |
| Central Massachusetts | 5b, 6a | May 1 - May 15 | Sep 25 - Oct 10 |
| Coastal/Cape | 6b, 7a | Apr 15 - May 1 | Oct 15 - Nov 1 |
Onions Planting Schedule for Massachusetts
Western Massachusetts (Zones 5b, 6a)
Average last frost: May 1 - May 20 · Average first frost: Sep 20 - Oct 10
Central Massachusetts (Zones 5b, 6a)
Average last frost: May 1 - May 15 · Average first frost: Sep 25 - Oct 10
Coastal/Cape (Zones 6b, 7a)
Average last frost: Apr 15 - May 1 · Average first frost: Oct 15 - Nov 1
Growing Onions in Massachusetts
Onions in Massachusetts's Climate
Long-day onions are your type. Plant sets or transplants as soon as ground can be worked in spring. For the largest bulbs, start from seed indoors 10-12 weeks before last frost. Your June day length (15+ hours) triggers proper bulbing. Cure in a warm, dry location for 2-3 weeks before storage.
Soil Considerations for Massachusetts
Rocky, acidic New England soils. Glacial deposits. Raised beds popular. Amend heavily with compost. Loose, well-drained soil is especially important for onions since the edible portion grows underground. If your soil is heavy clay, consider raised beds.
Massachusetts Climate & Growing Season
Four seasons. Maritime influence moderates coastal areas. Cold winters. Good growing season with adequate moisture. Onions can handle frost well, which is an advantage in Massachusetts's climate. You can push planting dates earlier in spring and extend into fall.
Growing season length varies across Massachusetts: Western Massachusetts (5b, 6a) has a last frost around May 1 - May 20, while Coastal/Cape (6b, 7a) sees frost end around Apr 15 - May 1. 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