When to plant onion in Hawaii
Hawaii spans USDA zone 12a, so the right time to plant onion shifts by weeks across the state. The window to transplant seedlings outdoors runs from about December 29 in Kapaa to December 29 in Kapaa — below are local dates for 1 cities, each computed from its own frost dates.
| City | Zone | Last frost | First frost | Transplant out |
|---|---|---|---|---|
| Kapaa | 12a | January 26 | January 24 | December 29 – January 12 |
Onion in Hawaii: FAQ
When can I plant onion in Hawaii?
Across Hawaii, the time to transplant onion spans roughly December 29 in Kapaa to December 29 in Kapaa, each following that city's local frost dates.
Does the onion planting date vary across Hawaii?
Yes. Hawaii publishes 1 cities with their own frost dates, so the right onion planting window shifts by weeks between the warmest and coldest parts of the state — use your city's page for the exact dates.
How long does onion take to grow in Hawaii?
Onion takes about 90–110 days to reach harvest once planted — check that this fits inside your city's frost-free season on its place page.
Never miss a window in your area
An email when it’s time to start seeds, transplant, and sow — timed to your frost dates. Double opt-in, one-click unsubscribe, no spam.