New USA Hardiness Zone Map reflects warmer climate

At last Americas 82 million gardeners can now use accurate climate information to select the plants they will grow.

Launched on 25th January 2012, the new Arbor Hardiness Zone Map separates America  into ten different temperature zones  and reflects that many areas have become warmer since 1990 when the last USDA hardiness zone map was published. Significant portions of many states have shifted at least one full hardiness zone. Much of Illinois, Indiana, and Ohio, for example, have shifted from Zone 5 to a warmer Zone 6. Some areas around the country have even warmed two full zones..

These long-awaited changes  show northward warming trends, while also targeting a few colder areas in the mountains. Growers in climates where warmer is the new norm can grow species of plants that would have perished in a colder zone.

“I think it will lead people to experiment with many plants they might not have otherwise,” says Steve Carroll, director of public programs at the State Arboretum of Virginia in Boyce, Va. “Nurseries might stock differently. We could see it will have an impact on all kinds of things in the garden world.”

The “hardiness” guide, last updated in 1990, lists average minimum temperatures for different latitudinal zones. Each zone is based on 10 degrees Fahrenheit. Two new zones were added in hotter climates this year for a total of 13 zones. 1 is coldest (-60 to -50). 13 is hottest (60 to70) and is found only on Hawaii and Puerto Rico.

This new map uses 30 years of weather data gathered from 1976 to 2005 and is more precise than the 1990 version, showing smaller areas and accounting for higher elevations and bodies of water that can influence temperature. It has been designed for the Web and allows people to enter their ZIP code to see their zone down to half-mile segments.

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- who has written 872 posts on My Climate Change Garden.

I am not an experienced gardener - more of an enthusiastic amateur who learns by trial and error and who is keen to "manage" the effects of shifting weather patterns on my garden. Writing this blog is my passion and it has evolved over 12 years to inspire engagement with climate change outside our back doors, in our personal gardens and green spaces. My mission is to fertilise and expand this platform to grow a community of global gardeners communicating about the effects of climate change on our plants and exploring how each individual can make small changes in our lives to become more sustainable. The future of our gardens and #OurPlanet is in our hands - please plant your own seeds for our collective sustainable future.

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