ZIP precision

Why ZIP precision beats a zone-only planting calendar

USDA hardiness zones explain winter cold risk. Vegetable timing also needs the local last frost, first frost, soil warmth, and the crop's own timing rules.

A zone is a broad climate band

Two places can share a USDA zone and still have different spring frost timing. GrowZone narrows the answer by mapping a ZIP to a representative frost station before calculating crop windows.

ZIP-level pages make the answer citable

Each crop page states the date, frost station, USDA zone, update date, and local-verification warning in static HTML so gardeners and answer engines can read the same source trail.