Planning tool
ZIP Code Hardiness Zone Lookup
Use the committed OSU PRISM ZIP artifact as a read-only hardiness-zone source, then keep frost dates, soil temperature, and planting windows in separate local planning steps.
Inputs
- ZIP code
- Matches a five-digit ZIP or ZIP+4 prefix against the committed OSU PRISM 2023 USDA Plant Hardiness Zone ZIP Code Listings.
- Lookup artifact
- /data/usda-phzm-zip-lookup.json generated from OSU PRISM 2023 USDA Plant Hardiness Zone ZIP Code Listings.
- Manual USDA check
- Use the official USDA Plant Hardiness Zone Map when parcel-level or microclimate detail matters.
What it returns
- Resolved USDA half-zone and average annual extreme minimum temperature band.
- Source dataset, dataset year, source URL, checksum, attribution, and ZIP-boundary caveat.
- No last frost dates, first frost dates, planting windows, crop recommendations, or vendor recommendations.
Lookup source decision
- Source dataset
- OSU PRISM 2023 USDA Plant Hardiness Zone ZIP Code Listings
- Lookup artifact
- /data/usda-phzm-zip-lookup.json with 39,921 ZIP records.
- Dataset year
- 2023
- Source URL
- https://prism.oregonstate.edu/phzm/data/2023/phzm_us_zipcode_2023.csv
- Source checksum
- bd5a10ad97d6442784421a488e0ddfb775c44ee64b0b4166f6508495c3a1283c
- Attribution
- USDA Plant Hardiness Zone Map 2023; GIS datasets are owned by Oregon State University and produced by OSU PRISM with USDA-ARS support.
Lookup caveats
- ZIP boundary
- ZIP Code listings are not parcel-level hardiness-zone results; local microclimates, elevation, and ZIP boundaries can differ from a garden site.
- Frost-date boundary
- Do not infer last frost dates, first frost dates, or planting windows from the ZIP result.
- Hardiness-zone limitation
- Hardiness zones describe average annual extreme minimum winter temperature, not last frost dates, first frost dates, soil temperature, or annual vegetable planting windows.
- Manual fallback
- Use the official USDA ZIP search and local extension frost-date guidance before making planting decisions.
Use the lookup
- USDA Zone and Frost-Date Planner Open the hydrated planner ZIP lookup and keep frost dates separate from hardiness-zone results
- Regional Planting Guides Use local extension timing when a ZIP result is too broad; 111 source-backed regional guides cover All 50 U.S. states.
Timing tools
- Planting Calendar Tool Convert explicit frost dates into crop task dates
- Fall Planting Planner 63 first-frost-window varieties
- Fall-Planting Seeds 63 first-frost-window varieties
- Cool Season Seeds Crops that can fit spring or fall windows after local frost checks
- Warm Season Seeds Crops that need frost-free warmth after local frost checks
Source basis
- USDA Plant Hardiness Zone Map Official 2023 USDA PHZM site with interactive map and user-facing ZIP Code search
- USDA PHZM Map Creation Explains GIS data ownership, attribution conditions, ZIP finder, and 1991-2020 normals
- OSU PRISM 2023 PHZM GIS datasets Official OSU PRISM page for 2023 PHZM grid, shapefile, KML, and ZIP Code Listing datasets
- OSU PRISM 2023 PHZM ZIP Code Listings CSV Official CSV listing ZIP Code, USDA half-zone, temperature range, and zone title for build-time lookup
- USDA Ag Data Commons 2023 PHZM rasters Official 2023 raster dataset for future GIS-based zone lookup work
- USDA PHZM How to Use the Maps Describes ZIP search, map use, hardiness-zone limits, and microclimate caveats