Field guide
When to plant onions in USDA Zones 9–10
In USDA Zones 9–10, the planner’s broad outdoor planting window for onions runs from January to February, with a second window from October to December. Onions takes 90–120 days from planting to first harvest.
Open plannerPlanting calendar for USDA Zones 9–10
- Spring planting
- January to February
- Fall planting
- October to December
- Days to harvest
- 90–120 days
- Water needs
- low
What USDA Zones 9–10 do—and do not—tell you
These zones span average annual extreme minimum temperatures of roughly 20°F to 40°F. That is useful climate context, but it does not determine your exact frost dates. Check a local forecast or county Extension calendar before planting tender crops.
How to know when to harvest
- Tops fall over naturally and begin to yellow
- Neck softens at the soil line
- Bulb feels firm and has reached expected size
Want a plan that accounts for your crops, growing method, equipment, and plant conditions? Open the free planner for a daily crop checklist and adaptive harvest forecast.
About this field guide
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