USDA Plant Hardiness Zones — Complete Guide

Find your zone, understand what it means, and pick plants that thrive where you live.

What are USDA hardiness zones?

The USDA Plant Hardiness Zone Map divides the U.S. into 13 zones based on the average lowest winter temperature. Each zone represents a 10°F range, with subzones (a/b) splitting that into 5°F increments. The 2023 update reflects warming trends — about half of U.S. ZIPs shifted to a slightly warmer zone vs. the 2012 map.

Why your zone matters

Zone determines which perennials, trees, and shrubs survive your winter. A "Zone 8" lavender will die in Zone 5; a "Zone 5" apple will struggle to fruit in Zone 9 because it needs cold dormancy. For annuals (tomatoes, basil), zone matters less — frost dates matter more.

How to use your zone

1. Buy zone-rated perennials. Plant tags say "Hardy to Zone 5" — that's the coldest zone where it survives.
2. Match annuals to season length, not zone. Long-season tomatoes need 90+ frost-free days.
3. Watch microclimates. A south-facing wall can be a half-zone warmer; a low spot can be a half-zone colder.
4. Push the zone if you must — but plan for failures. Zone-pushing is fun. It's also where most beginner heartbreak comes from.

Common questions

Is my zone the same as my growing season length?

No. Zone = winter cold. Season length = days between last and first frost. Zone 5 in Maine has a shorter season than Zone 5 in Colorado at altitude.

Did the zones change recently?

Yes, in November 2023 the USDA released a new map. Many areas warmed by half a zone. If you used to be Zone 6a, you might now be Zone 6b.

What about heat zones?

The American Horticultural Society publishes a separate Heat Zone Map (1–12) based on summer high days. For most U.S. gardeners, USDA hardiness is the more useful single number.