USDA Hardiness Zone Map: How to Find Your Zone

The USDA Plant Hardiness Zone Map divides the US into 13 zones based on the average coldest winter night of the year. Each zone spans 10°F and is split into “a” and “b” halves of 5°F. To find your zone, enter your ZIP code on the USDA Agricultural Research Service’s interactive map at planthardiness.ars.usda.gov. The current map was released in November 2023, using temperature data from 1991 to 2020, and it shifted roughly half the country into a half-zone warmer than the 2012 version. Your zone tells you which perennials, shrubs and trees are likely to survive winter where you live. It does not tell you when to plant vegetables; for that you need your local frost dates. Here is how the map works and how to use it.

In this guide

1. What the Hardiness Zone Map Measures
2. Zone Temperature Ranges
3. How to Find Your Zone by ZIP Code
4. What Changed With the 2023 Map
5. What Your Zone Means for Planting
6. Examples: Reading Zones on Real Plants
7. What the Zone Map Does Not Tell You
8. Microclimates: Your Yard Has Its Own Zones
9. Using Zones When You Shop
10. Frequently Asked Questions

What the Hardiness Zone Map Measures

The map shows the average annual extreme minimum temperature: for each location, researchers took the single coldest temperature of each winter over a 30-year period and averaged those values. That number is a good predictor of whether a plant’s roots, buds and stems will survive winter. It is not the coldest temperature ever recorded, so a severe winter can still drop below your zone’s range.

The 2023 edition was produced by the USDA Agricultural Research Service with Oregon State University’s PRISM Climate Group. It uses data from more than 13,000 weather stations and a finer mapping grid than the previous edition, which shows local variation in hills, valleys and near large bodies of water more accurately.

Zone Temperature Ranges

Zone	Average extreme minimum (°F)	Example areas
1	-60 to -50	Interior Alaska
2	-50 to -40	Parts of Alaska
3	-40 to -30	Northern Minnesota, North Dakota
4	-30 to -20	Upper Midwest, northern New England, Rockies
5	-20 to -10	Iowa, much of Michigan and upstate New York
6	-10 to 0	Ohio Valley, Pennsylvania, southern New England
7	0 to 10	Mid-Atlantic, Tennessee, Oklahoma
8	10 to 20	Gulf states inland, Pacific Northwest lowlands, much of Texas
9	20 to 30	Central Florida, Gulf Coast, central California
10	30 to 40	South Florida, coastal Southern California
11	40 to 50	Florida Keys, Hawaii lowlands
12	50 to 60	Puerto Rico, parts of Hawaii
13	60 to 70	Warmest parts of Puerto Rico and Hawaii

Each zone is split into halves. Zone 6a, for example, covers -10 to -5°F, and 6b covers -5 to 0°F. Plant tags often list only the whole zone, such as “zones 5 to 9”, which means the plant should survive winters from the cold end of zone 5 to the warm end of zone 9.

How to Find Your Zone by ZIP Code

1. Go to the USDA ARS Plant Hardiness Zone Map website (planthardiness.ars.usda.gov).
2. Type your ZIP code into the search box.
3. The site returns your zone, half zone and the temperature range for that ZIP code.
4. For more precision, use the interactive map to zoom in on your exact location. Large or hilly ZIP codes can span more than one half zone.

Many state extension services, seed companies and garden centers also offer ZIP lookups based on the USDA data. If two sources disagree, they may be using the older 2012 map. Use the current USDA site as the reference.

What Changed With the 2023 Map

Compared with the 2012 map, which used 1976 to 2005 data, about half of the country shifted to the next warmer half zone, and the rest mostly stayed the same. Two new zones, 12 and 13, were added to cover the warmest areas of Hawaii and Puerto Rico. Part of the change reflects warmer winters, and part reflects more weather stations and better mapping methods, so a shift on the map does not always mean your own winters have warmed by that much.

Practically, if your zone moved from 6a to 6b, plants rated to zone 6 were already a good fit and still are. Be cautious about pushing into plants rated only for your new half zone’s warm edge; one cold winter can still kill them.

What Your Zone Means for Planting

Perennials, shrubs and trees

This is what the map is for. A perennial, shrub or tree rated for your zone or colder should survive a typical winter in the ground. When in doubt, choose plants hardy to at least one zone colder than yours, especially for expensive trees and for containers, which expose roots to more cold than the ground does. A plant rated zones 4 to 8 is a safe bet in zone 6; a plant rated zones 7 to 10 is a risky bet there.

Vegetables and annuals

Most vegetables and annual flowers complete their life in one season, so winter cold does not matter to them. What matters is the length of your frost-free season and when the last spring frost and first fall frost arrive. Your zone gives a rough idea, as colder zones generally have later last frosts and shorter seasons, but two places in the same zone can have frost dates weeks apart. Look up your local average frost dates from your state extension service or a frost date calculator, and plan seed starting from those. Our guide to seed starting indoors explains how to count back from your last frost, and the vegetable gardening hub covers season planning.

Rough planting guide by zone

Zone	Typical last spring frost window	Season notes
3 to 4	Mid-May to early June	Short season; choose fast-maturing varieties and start warm crops indoors
5 to 6	Late April to mid-May	Moderate season; most warm crops do well with indoor starts
7	Early to mid-April	Long season; spring and fall crops both work
8	Mid-March to early April	Long, hot summers; plant cool crops in fall and winter
9 to 10	Rare frost or none	Main garden season is fall through spring; summer heat stalls many crops

These windows are generalizations. Always confirm with local frost data.

Examples: Reading Zones on Real Plants

A few familiar plants show how zone ratings play out in practice. Panicle hydrangeas such as Limelight are rated roughly zones 3 to 8, so they survive Minnesota winters but can struggle with heat in the Deep South. Crape myrtles are generally reliable from zone 7 south; in zone 6 many die back to the ground and in colder zones they rarely survive. Rosemary is usually hardy only from about zone 7 or 8 south, which is why northern gardeners grow it in pots and bring it indoors. Figs fruit reliably in the ground from about zone 7 south, while hardy varieties can survive in protected spots in zone 6. Lavender is often rated zones 5 to 9, but in wet clay it may die in winter even within that range, a reminder that drainage matters as much as cold.

The pattern to notice is that ratings are a starting point. Plants near the cold edge of their range benefit from a warm wall, good drainage and winter mulch, and plants near the warm edge benefit from afternoon shade and steady water.

What the Zone Map Does Not Tell You

• Summer heat. A plant hardy to zone 9 in winter may still melt in a humid Southern summer. The American Horticultural Society’s Plant Heat Zone Map addresses heat tolerance separately.
• Rainfall and humidity. Zone 8 in Seattle and zone 8 in central Texas are very different gardens.
• Snow cover. Reliable snow insulates roots, so some perennials survive colder winters under snow than in open, windy ground.
• Soil and drainage. Many plants die in winter from wet roots rather than cold. Lavender and many Mediterranean herbs are a classic example.
• Duration and timing of cold. A sudden hard freeze after a warm spell can damage plants that would survive the same temperature in midwinter.

Microclimates: Your Yard Has Its Own Zones

Within a single yard, conditions vary enough to change what survives. South- and west-facing walls absorb heat and can support plants a half zone warmer. Low spots collect cold air and frost, behaving colder than the rest of the yard. Areas exposed to winter wind dry out and freeze harder. Urban heat islands and areas near large lakes or the ocean run warmer than surrounding countryside. Use warm spots for borderline plants, and keep tender plants out of frost pockets. Our guide on how to protect plants from frost covers practical ways to stretch your zone.

Using Zones When You Shop

• Read the plant tag’s zone range and make sure your zone falls within it, ideally not right at the cold edge.
• Be wary of big-box stores stocking plants shipped from warmer regions; tags are accurate, but not everything sold locally is hardy locally.
• For container plants left outdoors in winter, subtract one or two zones from your rating, or move pots to a sheltered spot.
• Local nurseries and extension services know which “borderline” plants reliably succeed in your area.