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[SG] AHS heat zones

Okay, guys, are you ready for the new American Hort. Society's heat zones?
Some or many wholesalers will be putting four numbers on tags: USDA zones
that that plant will live through, and AHS heat zones that that plant will
thrive in.  They've taken average temps from 1976 to l995, and figured out
how many days of 86 degrees F. (30 degrees C.) an area usually gets during
a growing season.  There are 12 zones, zone 1 having less than one day of
86 or higher on average, and zone 12 has more than 210.  The idea behind
this is that some hot weather is far too stressful for certain plants, and
they should not be grown in that kind of climate.  86 degrees was chosen
because some cellular protein is damaged at that temperature.  I think it's
a superb idea.  Just got my copy of "Heat-Zone Gardening" by Dr. H. Marc
Cathey, President Emeritus of the American Hort Society.  Pub. date is
1998, and it's a Time-Life book (discount if you're a member of AHS).

Nurseries in Boise are enthusiastic, having seen some plants expire of
alleged winterkill, when the winter temps were not that severe, but the
summer had been.  Gene, Marilyn and others who have nurseries will like the
new system, I think.  Margaret
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