GrowZone

Seed-start answer

Start tomatoes seeds indoors around Mar 14

In ZIP 60601, start tomatoes seeds indoors around Mar 14, about 42 days before the Apr 25 last-frost estimate.

Source: chicago-ohare frost station, USDA zone 6a, 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 60601, the Chicago frost station, and the Apr 25 last-frost estimate.

Seed starting schedule

Tomatoes dates for Chicago, IL

StepDateHow to use it
Start IndoorsMarch 14, 2026Start seeds under lights or in a bright indoor seed-starting space.
Transplant OutdoorsMay 2, 2026Move hardened-off seedlings outside after the frost-risk window.