Growing palms and tropicals in cold climates
Growing palms and tropicals in cold climates
I just found this press release from the City University of New York in which a faculty person says that zones have shifted upward (warmer) by a half zone for about 1/3 of the continental US just since the last USDA map. That "old" map used data through 2005.
http://www1.ccny.cuny.edu/advancement/news/Warmer-Temperatures-Make-New-USDA-Plant-Zone-Map-Obsolete.cfm#.UFJEXi1PQ6I.facebook
After my Zone 8 winter last year, it makes sense, unless I think back to the zone 5 winter the previous year... .
All it takes is one bad year to make any of the maps irrelevent for long term culture of plants in borderline areas. I don't think the old data should be dismissed or else many people will be disappointed. What I think would be more usefull is the average frequency of different ultimate low temberatures. It is one think if your zone 8 shrub dies in a zone 5 equivlent freeze and another if your 30 foot tall tree dies.
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