USDA Plant Hardiness Zone Finder

Enter your minimum winter temperature (in Fahrenheit or Celsius) to instantly find your USDA plant hardiness zone. See your zone number and subzone letter, temperature range, plants that thrive, typical frost dates, and example cities that share your zone. Built on the 2023 USDA Plant Hardiness Zone Map, which divides North America into 13 zones based on average annual minimum winter temperature.

Gardening

Find Your Hardiness Zone

Quick presets

Enter the average lowest winter temperature for your location.

How to Use

  1. 1
    Enter your minimum winter temperature

    Toggle between Fahrenheit and Celsius, then enter the lowest winter temperature your location typically experiences — this is your average annual extreme minimum, not a record cold snap.

  2. 2
    Read your zone and details

    Read the matching USDA zone number and subzone letter (a = colder half, b = warmer half), along with the full temperature range, typical plants that thrive, and average first and last frost dates.

  3. 3
    Compare against known cities

    Use the preset buttons (Minneapolis 3b, Chicago 5b, Atlanta 8a, Miami 10b, San Diego 10b) to compare your zone against well-known US cities and validate your reading against nearby gardeners.

About

The USDA Plant Hardiness Zone system is the single most influential framework for selecting perennial plants in the United States. First published by the U.S. Department of Agriculture in 1960 and revised in 1965, 1990, 2012, and 2023, the map divides North America into numbered zones based on the average annual extreme minimum temperature — the coldest night of a typical winter, averaged over several decades. The current 2023 edition uses 30 years of weather data from 1991 to 2020, incorporates a much denser grid of weather stations, and applies modern climate interpolation to draw zone boundaries at roughly half-mile resolution across the contiguous United States, Alaska, Hawaii, and Puerto Rico.

Each full zone spans a 10°F (5.6°C) band of average winter lows and is split into an 'a' (colder) and 'b' (warmer) subzone, giving gardeners 26 named bands from Zone 1a (below -60°F / -51°C) at the arctic edge of Alaska to Zone 13b (above 65°F / 18°C) in the tropical Caribbean. A plant's hardiness rating tells you the lowest zone — and thus the coldest average winter — in which it is expected to survive outdoors without extraordinary protection. Combine this finder with the PlantFYI plant database to select trees, shrubs, perennials, and bulbs that match your local winter climate, then layer in microclimate knowledge, frost date planning, and soil data to build a garden that thrives year after year.

FAQ

What are USDA plant hardiness zones?
USDA plant hardiness zones divide North America into 13 numbered zones based on the average annual extreme minimum winter temperature. Each full zone represents a 10°F (5.6°C) band, and each zone is split into 'a' (colder half) and 'b' (warmer half) 5°F subzones. Zones are the single most widely used reference for choosing perennials, shrubs, and trees likely to survive winters in your garden, and they appear on almost every seed packet and nursery tag sold in the United States.
How do microclimates affect my hardiness zone?
Official USDA zones are calculated from weather station averages over a 30-year period, but real gardens are full of microclimates that shift effective hardiness by a half zone or more. South-facing walls, paved courtyards, windbreaks, and urban heat islands keep nearby plants warmer, while frost pockets at the bottom of slopes, exposed hilltops, and north-facing yards run colder. It is common for gardeners in Zone 6b to successfully overwinter Zone 7 plants against a brick house, or to lose Zone 6 plants in a low, wet corner.
What changed in the 2023 USDA hardiness zone map?
The 2023 USDA Plant Hardiness Zone Map uses weather data from 1991 to 2020, replacing the 2012 map built on 1976 to 2005 data. About half of the contiguous United States shifted roughly one half-zone warmer, reflecting a warming trend in winter low temperatures. The new map also uses a much denser weather station network with improved interpolation, so many local boundaries were redrawn even where the overall trend did not change.
How do frost dates relate to my hardiness zone?
Hardiness zones describe winter cold — not frost timing. The last spring frost and first fall frost dates depend on latitude, elevation, and local geography, and can differ by weeks between gardens in the same zone. Zones are the right tool for selecting perennials that survive winter, while frost dates are the right tool for scheduling seed starting, transplanting, and frost protection of annuals and vegetables. Pair them both when planning your garden year.
What is the difference between zone 6a and zone 6b?
Each numbered USDA zone is split into two 5°F (2.8°C) subzones. Zone 6a covers average annual lows from -10°F to -5°F (-23°C to -21°C), while Zone 6b covers -5°F to 0°F (-21°C to -18°C). The subzone matters most when a plant is rated right at your zone boundary — a perennial labeled hardy to Zone 6 generally means 6a and warmer, while one labeled 6b is safer one half-zone warmer. Subzones let nurseries give more precise ratings without adding entire new zone bands.
Next
Plant Hardiness Zone Calculator
← All Tools