2006 arborday.org Hardiness Zone Map
The National Arbor Day Foundation has recently completed an extensive updating of U.S. Hardiness Zones based upon data from 5,000 National Climatic Data Center cooperative stations across the continental United States.
Find it at: http://arborday.org/media/zones.cfm
Lori Bushway | Resources, on-line publications
Hardiness zones per recent revision are not true. USDA maps based on several ‘normal periods” of 30 yrs and in addition, your researchers have obviously used ‘urban heat island” stations which significantly bias the results. Over 25 percent of the HCN stations are rated as improperly placed. Morevover 15 years is simply too short. I suggest u retract this as it will lead to massive plant misplacements.
A. Lind