GrowZone

Seed-start answer

Start tomatoes seeds indoors around Mar 24

This uses ZIP 80012, the Denver frost station, and the May 5 last-frost estimate.

Seed starting schedule

Tomatoes dates for Aurora, CO

StepDateHow to use it
Start IndoorsMarch 24, 2026Start seeds under lights or in a bright indoor seed-starting space.
Transplant OutdoorsMay 12, 2026Move hardened-off seedlings outside after the frost-risk window.