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Planting Zones Heading North

By Climate Central

What kinds of flowers, shrubs and trees you’ll find at your local nursery depends on your climate — how warm it tends to get in summer, and how cold in winter. A plant that’s happy in Wisconsin might be miserable in Alabama, and vice versa.

The U.S. Department of Agriculture has formalized these differences into "hardiness zones" — strips of similar climate that run more or less east-to-west (except in the high mountains), where particular plants should do especially well. But as the planet warms under its thickening blanket of greenhouse gases, those zones are shifting northward. The result, according to the latest National Climate Assessment, is that “...species, including many iconic species, may disappear from regions where they have been prevalent or become extinct, altering some regions so much that their mix of plant and animal life will become almost unrecognizable.” For example, the National Wildlife Federation projects that by 2080, the Mississippi Magnolia and the Ohio State Buckeye will shift out of their current zone. 

The authors are talking about natural ecosystems, but the same holds true for our backyard gardens. Similar to the USDA hardiness zone maps, NOAA created a set of maps to reflect planting zones based on changing average annual winter minimum temperatures. The animation above, based on the NOAA climate-related planting zone maps, show you just how the changes have played out so far.

All of this might be good news if you’ve always wished you could grow warmer-weather flowers in your garden and bad news if you love the garden you’ve got right now. Either way, it’s yet another indicator that we live in a warming world.