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What Is a Plant Hardiness Zone and Why Does It Matter?

A woman waters plants in a garden.
goodluz/Shutterstock.com

Not all of us are expert gardeners. There are a few basic things we all need to know if we’re going to try to turn your thumb green. Even if you are a pro gardener, a quick refresh doesn’t hurt. One of the major things to know about is plant hardiness zones.

So what are plant hardiness zones, and why do they matter?

Your hardiness zone is also known as your USDA zone. They are zones (obviously) established by the Department of Agriculture. They divide the United States into 11 different zones that are based on the minimum average annual temperature. Each zone is assigned a number.

The lower the temperature, the lower the number of the zone. Within those zones, there are designations “a” and “b.” These show smaller differences in temperature, five degrees difference to be exact.

A map shows the hardiness zones from the USDA.
USDA

Why does this matter? Well, they help you determine if what you want to plant can survive your environment. Plants—particularly perennials—have a zone that works best for them, and planting ones that correspond to your zone can help ensure they thrive.

As for using the map, you can find an interactive version on the USDA website. There, you can find your state on the map and then narrow things down by city and see the smaller increments within the zones.

If you plan to plant any perennials any time soon, these zones will be your new best friend.

Shea Simmons Shea Simmons
Shea Simmons is an Atlanta-based writer who has written about everything from whether Crisco is a good moisturizer to how to KonMari your space. Her work has appeared in Bustle, My First Apartment, and Make It Grateful. Read Full Bio »
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