GrowZone

Seed-start answer

Start tomatoes seeds indoors around Dec 25

In ZIP 85201, start tomatoes seeds indoors around Dec 25, about 42 days before the Feb 5 last-frost estimate.

Source: phoenix-skyharbor 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 85201, the Phoenix frost station, and the Feb 5 last-frost estimate.

Seed starting schedule

Tomatoes dates for Mesa, AZ

StepDateHow to use it
Start IndoorsDecember 25, 2025Start seeds under lights or in a bright indoor seed-starting space.
Transplant OutdoorsFebruary 12, 2026Move hardened-off seedlings outside after the frost-risk window.