Seed-start answer
Start watermelon seeds indoors around Mar 15
In ZIP 73102, start watermelon seeds indoors around Mar 15, about 21 days before the Apr 5 last-frost estimate.
Source: oklahoma-city-will-rogers frost station, USDA zone 7b, 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 73102, the Oklahoma City frost station, and the Apr 5 last-frost estimate.
Seed starting schedule
Watermelon dates for Oklahoma City, OK
| Step | Date | How to use it |
|---|---|---|
| Start Indoors | March 15, 2026 | Start seeds under lights or in a bright indoor seed-starting space. |
| Transplant Outdoors | April 19, 2026 | Move hardened-off seedlings outside after the frost-risk window. |
| Direct Sow | April 19, 2026 | Sow seed outside when the crop and soil can handle the window. |