Methodology

How GrowZone turns a ZIP code into a planting calendar.

GrowZone maps supported ZIP codes to a representative frost station and USDA hardiness zone, then applies crop-specific timing rules.

1. ZIP to representative station

Each supported ZIP is assigned to a representative station with last-frost and first-frost estimates. This is not a guarantee; it is a planning signal.

2. Station to crop windows

Each crop has timing rules for seed starting, transplanting, direct sowing, and harvest. Warm-season crops wait longer after frost than cool-season crops.

3. Local verification

Gardeners should verify with local cooperative extension guidance, especially for unusual microclimates, high-value crops, or current-year weather anomalies.

4. Measurement

GrowZone reports canonical metrics through /api/metrics and partner API hooks. GA4 is optional and never replaces the canonical metrics contract.