What Is a Plant Hardiness Zone?

Before You Start Gardening

If you're just getting into gardening, first learn which U.S. Department of Agriculture (USDA) plant hardiness zone you live in. Your zone number, developed by the USDA, lets you know which plants will do best in your yard based on the climate you live in.

What Your Zone Means

The USDA divides the country, and Puerto Rico, into 13 zones based on a location's annual minimum winter temperature. Zone 1, for instance, includes Fairbanks, Alaska, and the northern islands of Canada. Zone 11 includes most of Hawaii. Zones 12 and 13 are found in Puerto Rico. Each planting zone is further subdivided into sub-zones, ‘a’ and ‘b’, for better accuracy.

Planting in Your Zone

You'll find that most plants and seeds you buy will come with a label listing their growing zones. To find out what zone you're in, view the USDA Plant Hardiness Zones map, which was updated by the USDA in 2023 to reflect weather data as recent as 2012.

First and Last Frost Dates

Once you determine which Plant Hardiness Zone you are in, become familiar with your zone’s average first and last frost date. These dates are essential for knowing when it’s safe to plant without the risk of frost damage. Below are the ranges of approximate first and last frost dates for each hardiness zone. For first and last frost dates that are specific to your location, visit the National Gardening Association and enter your zipcode.

Zone 1

• Average first frost date: August 25-31
• Average last frost date: May 22-June 4

Zone 2

• Average first frost date: September 1-8
• Average last frost date: May 15-22

Zone 3

• Average first frost date: September 8-15
• Average last frost date: May 1-16

Zone 4

• Average first frost date: September 21-October 7
• Average last frost date: April 24-May 12

Zone 5

• Average first frost date: October 13-21
• Average last frost date: April 7-30

Zone 6

• Average first frost date: October 7-31
• Average last frost date: April 1-21

Zone 7

• Average first frost date: October 29-November 15
• Average last frost date: March 22-April 3

Zone 8

• Average first frost date: November 7-28
• Average last frost date: March 13-28

Zone 9

• Average first frost date: November 25-December 13
• Average last frost date: February 6-28

Zone 10

• Average first frost date: December 15-31
• Average last frost date: January 1-15

Zone 11+

• Average first frost date: No usual frost
• Average last frost date: No usual frost

Other Weather Factors to Consider

Keep in mind that you should consider several other factors in addition to your hardiness zone. These include the type of soil you're working with, altitude, moisture, humidity, heat and wind. If you live in a hot climate, consider checking out the American Horticultural Society's Heat Zone Map. This map divides the country into 12 zones, which are based on the average number of days per year that a region experiences temperatures over 86 °F.

Going Native

Knowing your plant hardiness zone is important, but it's easy to grow a vibrant and healthy garden by working with plants that are native to your region. Learn how with our article Gardening with Native Plants.