On 1/25/2012 the USDA in association with OSU announced and unveiled the latest version of the Cold Hardiness Zones Map for the U.S.   Nursery Management magazine has done a nice summary of the changes here in NMPro so I won't repeat it here.  In short, zones have shifted both due to warming trends but also more accurate geographically due to better data and technology.  Some areas are now colder or warmer on the zone chart as technology is able to take into account geographical features like elevation, bodies of water, etc.

I like the new website.  It is very interactive and lets you or your customers enter a zip code to see their cold hardiness zones.  You also can zoom in, select regional maps and download the maps (warning - big files).  I have pulled down the full Illustrator file and converted to a 24"x36" poster sized pdf file.  Just have to find a place to print it.

Here is the link to the new USDA Cold Hardiness Zone charts and website.

This tool is very handy when seeing where cold will damage trees and plants.  It is not so handy when determining whether a tree or plant will thrive in a zone as it does not take into account heat, length of season, humidity, summer rain, etc.  This is why we like the Sunset Climate Zones although that could do with a facelift with more accurate maps using the latest technology.

Ron Ludekens 1-26-2012