Planning tool

USDA Zone and Frost-Date Planner

Compare USDA hardiness-zone temperature bands with local last-frost and first-frost dates so annual vegetable, herb, and flower timing is not reduced to zone alone.

Planning tool

Current zone and frost context

Zone 6B needs frost-date context

Zone 6B is winter context only. Choose a regional guide or local last-frost and first-frost dates before using planting calendars; keep ZIP lookup as a hardiness-only check.

USDA zoneZone 6B
Last frostApr 15
First frostOct 15
Season length183 frost-free days

Inputs

Regional frost dates first
Use source-backed regional frost-date presets before manual last-frost and first-frost editing.
ZIP lookup first
Use the built-in OSU PRISM ZIP artifact in the hydrated planner before manually choosing a USDA hardiness zone.
USDA hardiness zone
Manual fallback for average annual extreme minimum temperature bands and perennial survival context.
Last frost date
Manual fallback that controls spring direct-sow, indoor-start, and transplant timing for annual crops.
First frost date
Manual fallback that controls fall planting windows and expected season length.

What it returns

Lookup source decision

Recommended provider
USDA Plant Hardiness Zone Map
Build-time ZIP lookup
ready. Use the official USDA Plant Hardiness Zone Map as the user-facing source and the official OSU PRISM 2023 USDA Plant Hardiness Zone ZIP Code Listings as the build-time browser lookup artifact. Keep the manual USDA ZIP search visible, preserve attribution and caveats, and do not infer frost dates or planting windows from ZIP results.
Regional preset path
Hydrated users can apply source-backed regional frost-date presets before manual date editing.
Lookup artifact
/data/usda-phzm-zip-lookup.json with 39,921 ZIP records.
Artifact dataset
OSU PRISM 2023 USDA Plant Hardiness Zone ZIP Code Listings
Integration rule
Use only a documented API or official USDA/OSU GIS data pipeline for automated ZIP or coordinate lookup; the current ZIP lookup uses the official OSU PRISM ZIP Code Listings artifact.
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.

USDA/OSU GIS guardrails

Pipeline status
Status: design-only. Browser lookup uses a committed build-time artifact from official OSU PRISM ZIP listings.
ZIP artifact source
OSU PRISM 2023 USDA Plant Hardiness Zone ZIP Code Listings: https://prism.oregonstate.edu/phzm/data/2023/phzm_us_zipcode_2023.csv
ZIP artifact caveat
ZIP Code listings are not parcel-level hardiness-zone results; local microclimates, elevation, and ZIP boundaries can differ from a garden site.
ZIP artifact boundary
Do not infer last frost dates, first frost dates, or planting windows from the ZIP result.
Data inputs
Use only official USDA/OSU or PRISM GIS data for automated lookup, including the 2023 grid, shapefile, raster, or ZIP-code datasets described by USDA.
Processing
Process GIS data offline or at build time into a small read-only lookup artifact; do not call interactive map requests from the browser.
Attribution
Show USDA-ARS and OSU attribution when presenting data or maps derived from the official GIS datasets.
Frost-date boundary
Return hardiness-zone results separately from frost-date planning; do not infer last frost dates, first frost dates, or planting windows from a zone result.
Result contract
Show the resolved USDA half-zone and average annual extreme minimum temperature band without deriving crop timing. Show USDA-ARS and OSU attribution next to the result whenever derived PHZM GIS data is used. Show ZIP boundary, centroid, and microclimate caveats near the result so gardeners do not treat the ZIP result as parcel-level advice. Keep the manual USDA ZIP search link available as a fallback next to automated results.
Blocked approach
Do not scrape undocumented ArcGIS, iframe, or browser network requests from the interactive USDA map.

Regional guide fallback

Regional timing paths

Season paths

Fall-window examples

Source basis

A frost date with the crops already attached

This planner gives you the dates. Five regions have those dates already applied to a published crop list.