When to Plant Onions in Alaska
In Alaska, the time to plant onions outside runs from Mar 7 – Mar 21 in Ketchikan to Apr 26 – May 10 in Kenai. In Anchorage, it's Apr 18 – May 2. The average last spring frost differs by about 7 weeks across the state (Apr 4 in Ketchikan, May 24 in Kenai), so use the dates for the town nearest you.
Onions are cold-hardy. Plant sets or transplants early so they grow leaves before long summer days trigger bulbing.
- Start indoors: 10–12 weeks before the last frost.
- Plant outside: 2–4 weeks before the last frost.
Onions planting dates in Alaska by city
| City | Zone | Start indoors | Plant outside |
|---|---|---|---|
| Anchorage | 5a | Feb 21 – Mar 7 | Apr 18 – May 2 |
| Bethel | 4a | Feb 26 – Mar 12 | Apr 23 – May 7 |
| Fairbanks | 2a | Feb 21 – Mar 7 | Apr 18 – May 2 |
| Homer | 6a | Feb 15 – Mar 1 | Apr 12 – Apr 26 |
| Juneau | 6a | Feb 8 – Feb 22 | Apr 5 – Apr 19 |
| Kenai | 4b | Mar 1 – Mar 15 | Apr 26 – May 10 |
| Ketchikan | 8a | Jan 10 – Jan 24 | Mar 7 – Mar 21 |
| Kodiak | 7b | Feb 4 – Feb 18 | Apr 1 – Apr 15 |
| Palmer | 5a | Feb 11 – Feb 25 | Apr 8 – Apr 22 |
| Sitka | 7b | Feb 8 – Feb 22 | Apr 5 – Apr 19 |
| Wasilla | 5a | Feb 21 – Mar 7 | Apr 18 – May 2 |
Calculated from each town's average (50%) frost dates, from the nearest NOAA station (1991–2020). Typical dates for the 2027 planting season, based on NOAA's 1991–2020 averages. They are long-term odds, not a forecast: always check your local forecast before planting. Zones: 2023 USDA Plant Hardiness Zone Map (USDA-ARS and Oregon State University). Not the official map; see planthardiness.ars.usda.gov.
See all frost dates in Alaska, or the general guide to when to plant onions.
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