Hardiness Zone Maps Shifting With Climate

You can grow Southern magnolia in Pennsylvania and kiwis in Oklahoma, but you wouldn't know that from the USDA's old hardiness zone map that gardeners use to plan their plantings, as USA Today details. They haven't been updated since 1990, and the past two decades have been marked by increasingly obvious climate changes.

In 2006, the Arbor Day Foundation took it upon itself to update those hardiness zone maps, and the results were shocking in their breadth, even if many gardeners had already witnessed the particular regional changes first-hand. The climate zones across the United States have shifted north, with no state unaffected. (A similar map USDA drafted in 2003 was rejected.)

USA Today focuses on the political firestorm that comes along with anything related to global warming. Should crop insurance programs change based on projections of future climate change, for instance? But a look at the two maps side-by-side shows clearly that climate change isn't a future-tense issue.

Arbor Day Foundation
Hardiness Zone Maps for the United States reflect recent climate change that isn't reflected on older USDA maps.
Click to enlarge.

USA Today published a cool graphic today that lets you easily compare the 1990 zone map to the 2006 iteration.

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