Gardening

Plant Hardiness Zone Calculator

Find your USDA plant hardiness zone

Determine your USDA plant hardiness zone based on location. Find minimum winter temperatures and discover which plants thrive in your area.

Find Your Hardiness Zone

Enter your ZIP code or select your region to determine your USDA plant hardiness zone.

Or select your zone manually:

Your USDA Hardiness Zone

Min Winter Temp

What This Means for Your Garden

Plants That Thrive in Zone

USDA Hardiness Zones Overview

Coldest (1) to Warmest (13)

How to Use

  1. 1
    Enter your location details

    Provide your ZIP code or the average minimum winter temperature your area experiences each year.

  2. 2
    View your hardiness zone

    See your USDA zone number and subzone letter along with the temperature range it represents.

  3. 3
    Browse recommended plants

    Explore perennials, shrubs, and trees rated for your zone that are likely to survive your winters.

About

The USDA Plant Hardiness Zone system is the most widely used framework for determining which perennial plants, shrubs, and trees can survive winter in a given location. It assigns every region a zone number based on the average annual extreme minimum temperature -- the coldest night of a typical winter, averaged over three decades. Each numbered zone spans 10 degrees Fahrenheit and is split into a colder 'a' half and a warmer 'b' half.

Knowing your zone is the essential first step in plant selection. A perennial rated to Zone 5 is expected to survive winter lows down to minus 20 degrees Fahrenheit, so a gardener in Zone 6 can plant it with confidence while a gardener in Zone 4 should consider it a risk. The calculator lets you find your zone quickly from a minimum temperature or location, then links to the PlantFYI database so you can immediately browse species rated for your conditions. Beyond the zone number, successful perennial gardening also depends on microclimates, soil drainage, snow cover, and wind exposure, which are discussed in the FAQ section. Pair your zone result with local frost date knowledge and soil pH data for the most complete picture of what will thrive in your garden.

FAQ

What is a plant hardiness zone?
A hardiness zone is a geographically defined area where a specific range of plants can grow, based on the average annual extreme minimum winter temperature. The USDA system uses 13 zones, each spanning a 10-degree Fahrenheit band, further divided into 'a' and 'b' subzones of 5 degrees each. Zone ratings appear on most plant tags and seed packets sold in the United States.
Can I grow plants rated for a warmer zone than mine?
Sometimes, with protection. Mulching root zones, planting against south-facing walls, using cold frames, or wrapping tender plants in burlap can effectively shift your microclimate by half a zone or more. Container growing is another option: grow the plant outdoors in summer and move it to an unheated garage or basement in winter. Success depends on the severity and duration of cold spells, not just the lowest temperature.
Why do two gardens in the same ZIP code have different zones?
Microclimates within a single neighborhood can vary by a full zone. Elevation, proximity to water, exposure to wind, urban heat island effects, and slope orientation all influence the actual minimum temperature a garden experiences. A hilltop garden exposed to wind may be a full zone colder than a sheltered courtyard a quarter mile away at the base of the same hill.
How often are USDA hardiness zones updated?
The USDA updates its hardiness zone map roughly every decade to incorporate the latest 30-year climate normals. The most recent edition was released in 2023, using data from 1991 to 2020. Previous editions were published in 2012, 1990, and 1960. Each update reflects shifts in average winter lows and improvements in weather station coverage and interpolation methods.
Do hardiness zones account for summer heat?
No. USDA hardiness zones only measure winter cold tolerance. Plants can fail in a zone they are rated for if summer heat or humidity exceeds their tolerance. The American Horticultural Society publishes a separate Heat Zone Map that rates areas by the number of days above 86 degrees Fahrenheit. For a complete picture, consider both winter hardiness and summer heat tolerance when selecting plants.