Quick planting window
| Start indoors | January to February |
|---|---|
| Transplant | February to March |
| Sow seeds | February to March |
| Estimated harvest | June to July |
| Risk | Medium risk |
Month calendar
Scan the year by month to see seed starting, sowing, transplanting, and harvest timing.
Onion is a reasonable spring choice for California if you adjust for your local microclimate.
Next: ZIP code personalization
This is a state-level planning window based on typical frost timing and crop rules. Use local Extension guidance or a ZIP code frost-date tool before planting.
Planning notes
Days to maturity
110
Covered states
20
Maturity range
28-240 days
Crop overview pages compare state windows; open a specific state page to see that state's frost dates, heat risk, and Extension source.
Onion growing notes
The calendar window is only the first step. These growing details affect survival, plant vigor, and harvest quality.
Sun
Full sun.
Soil
Loose, fertile soil with good drainage.
Spacing
4-6 inches for bulbs.
Container
Use wide containers at least 8-10 inches deep.
Watering
Keep evenly moist during bulb formation.
Common mistake
Choosing the wrong day-length onion type.
Beginner tip
Use sets or transplants if seed timing feels too long.
Month window table
| State | Spring transplant / sow | Spring harvest | Fall transplant / sow | Fall harvest |
|---|---|---|---|---|
| California | February to March | June to July | August to September | November to December |
| New York | April to May | July to August | June to July | October to November |
| Texas | February to March | June to July | July to August | November to December |
| Washington | April to May | July to August | July to August | October to November |
| New Jersey | April to May | July to August | July to August | October to November |
| Florida | January to February | April to May | September to October | December to January |
| North Carolina | March to April | June to July | July to August | November to December |
| Georgia | February to March | June to July | July to August | November to December |
| Illinois | March to April | July to August | July to August | October to November |
| Ohio | March to April | July to August | July to August | October to November |
| Pennsylvania | April to May | July to August | July to August | October to November |
| Michigan | April to May | August to September | June to July | October to November |
| Arizona | February to March | May to June | August to September | November to December |
| Oregon | March to April | July to August | July to August | October to November |
| Massachusetts | April to May | July to August | June to July | October to November |
| Minnesota | April to May | August to September | June to July | October to November |
| Virginia | March to April | July | July to August | November to December |
| Colorado | April to May | August to September | June to July | October to November |
| Tennessee | March to April | June to July | July to August | November to December |
| Missouri | March to April | July to August | July to August | October to November |
Sources and limits
This crop overview summarizes typical frost windows and crop rules across 20 states. Because it is not tied to one state, the links below point to representative state Extension sources; state and crop-state pages show the matching state source.
Note: this overview shows a sample of sources; each state page exposes its own Extension reference.
FAQ
When should I start onion indoors?
Onion is commonly started indoors about 10 weeks before the last frost date. The exact month changes by state.
Can I sow onion outdoors?
Onion can be sown outdoors when soil and nights are suitable. In California, the spring estimate is about February to March.
When should I transplant onion?
Onion is commonly transplanted about -4 weeks after the last frost date, after seedlings are hardened off.
How long does onion take to harvest?
Onion is listed at about 110 days to maturity. Cool weather, weak light, or stress can extend that timeline.
Is onion container friendly?
Yes. Use wide containers at least 8-10 inches deep.
What is the most common onion mistake?
Choosing the wrong day-length onion type.
Is onion better in spring or fall?
Both spring and fall can work in many states, but fall timing should count backward from the first frost date.
Is this ZIP-code accurate?
No. V1 uses conservative state-level windows and reserves ZIP-code frost dates, USDA zone matching, and reminders for the next phase.