"The official guide for 80 million gardeners and a staple on seed packets reflects a new reality: The coldest day of the year isn't as cold as it used to be. So some plants that once seemed too vulnerable to cold can now survive farther north.

It's the first time since 1990 that the U.S. Department of Agriculture has updated the map and much has changed. Nearly entire states, such as Ohio, Nebraska and Texas, are in warmer zones. The new guide, unveiled Wednesday at the National Arboretum, also uses better weather data and offers more interactive technology.

"It truly does reflect state of the art," said USDA chief scientist Catherine Woteki. Gardeners can register their zip code into the online map and their zone will pop up. It shows the exact average coldest temperature for each of the 26 zones, even though zones are based on five degree increments."

The USDA site to find the new map and features. Click on the map to zoom in.

http://planthardiness.ars.usda.gov/PHZMWeb/

Here's the link for the full article

https://www.mail.com/1001932-federal-map-what-to-plant-reflects-warming.html#.23140-stage-hero1-14

and here's the old zone map for comparison

http://www.garden.org/zipzone/index.php?img=swusa