Seed-start answer
Spinach is usually direct-sown around Dec 28
In ZIP 94102, spinach is usually direct-sown around Dec 28 instead of started indoors.
Source: san-francisco-downtown frost station, USDA zone 10a, last updated 2026-06-28. Verify locally before planting high-value crops because microclimates, current weather, and yard exposure can move the safe date.
This uses ZIP 94102, the San Francisco frost station, and the Jan 25 last-frost estimate.
Seed starting schedule
Spinach dates for San Francisco, CA
| Step | Date | How to use it |
|---|---|---|
| Direct Sow | December 28, 2025 | Sow seed outside when the crop and soil can handle the window. |