Seed-start answer
Start basil seeds indoors around Dec 21
In ZIP 94102, start basil seeds indoors around Dec 21, about 35 days before the Jan 25 last-frost estimate.
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
Basil dates for San Francisco, CA
| Step | Date | How to use it |
|---|---|---|
| Start Indoors | December 21, 2025 | Start seeds under lights or in a bright indoor seed-starting space. |
| Transplant Outdoors | February 4, 2026 | Move hardened-off seedlings outside after the frost-risk window. |
| Direct Sow | February 4, 2026 | Sow seed outside when the crop and soil can handle the window. |