Sources and Data Versions

The official datasets and Extension references behind Garden By ZIP, including versions, thresholds, and derived-use notes.

Last reviewed 2026-07-12

Climate and geography

USDA Plant Hardiness Zone Map, 2023 — ZIP zone table and 5°F half-zone bands.
U.S. Census 2025 ZCTA Gazetteer — representative coordinates, not USPS delivery boundaries.
NOAA U.S. Climate Normals 1991–2020 — 32°F spring and fall probability dates.

Plant guidance

Plant rules are cross-checked against university Extension sources including Minnesota, Illinois, Maryland, and Penn State. Each plant page links its reviewed references.

Derived presentation

Garden By ZIP is not the official USDA map, Census ZIP product, or NOAA service. Derived records retain source vintage, station ID, station distance, threshold, and visible warnings.