Sources and Data Versions

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

Last reviewed 2026-08-02

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.

Source freshness review

On August 2, 2026, Garden By ZIP rechecked the primary edition pages used by the site:

USDA continues to identify the 2023 Plant Hardiness Zone Map as its current map edition.
The Census Bureau continues to provide the 2025 national ZCTA Gazetteer used for representative coordinates.
NOAA continues to identify the 1991–2020 Climate Normals as the latest decadal normals; this site uses NOAA 1991–2020 Climate Normals v1.0.1.

These checks confirm source availability and edition; they do not turn climate normals into a forecast or replace current soil temperature and local garden conditions.

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.