Seed-start answer
Start watermelon seeds indoors around Jan 25
In ZIP 95113, start watermelon seeds indoors around Jan 25, about 21 days before the Feb 15 last-frost estimate.
Source: san-jose-mineta frost station, USDA zone 9b, 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 95113, the San Jose frost station, and the Feb 15 last-frost estimate.
Seed starting schedule
Watermelon dates for San Jose, CA
| Step | Date | How to use it |
|---|---|---|
| Start Indoors | January 25, 2026 | Start seeds under lights or in a bright indoor seed-starting space. |
| Transplant Outdoors | March 1, 2026 | Move hardened-off seedlings outside after the frost-risk window. |
| Direct Sow | March 1, 2026 | Sow seed outside when the crop and soil can handle the window. |