ZIP precision
Why ZIP precision beats a zone-only planting calendar
Same zone, different planting date
USDA zone 8a covers both Atlanta, GA and Raleigh, NC
A zone-only calendar gives them the same wide April window. GrowZone splits them by frost station.
| Zone-only calendar | GrowZone by ZIP |
|---|---|
| Zone 8a calendar: transplant tomatoes sometime in April. | Atlanta 30301 transplant Apr 5 (atlanta-hartsfield, Mar 29 last frost) vs Raleigh 27601 transplant Apr 17 (Apr 10 last frost), a 12-day gap inside the same zone. |
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.