California vs Florida climate zones

**C* T* E* <c*@gardenvista.com>**

For years I wondered why the American Horticultural Society Encyclopedia 
of Plants would list plants as USDA zone 8 or 9 that I knew grew happily 
in zone 10 in San Diego.  Pat Welsh, my mentor when I first began garden 
writing 26 years ago, explained it to me.  The tropical and subtropical 
areas of Florida and coastal California and much of Arizona are assigned 
the same USDA climate zones (9 and 10) because the average maximum cold 
temperatures in the two regions are similar.  However, many plants that 
flourish in the west are not suitable for Florida.  In the west, winters 
are wet, and summers are dry.  The opposite is true in Florida.  There 
the winters are dry, and the rainfall comes in summer.  Plus, as Marina 
mentions, in Florida you have humidity. Perhaps because most of the USDA 
researchers are based on the east coast, there is a predisposition to 
assign climate zones to plants that fall into the 9 and 10 zone based on 
their performance in Florida and not in the west.  As a result, it's not 
unusual to see a plant, such as the Southern magnolia (Magnolia 
grandiflora), that is listed in The American Horticultural Society A-Z 
Encyclopedia of Garden Plants as hardy in zones 7 - 9, that will grow 
just fine in zone 10 along the coast in southern California. 
    The problem caused by this misinformation is solved in the excellent 
catalogue produced by White Flower Farms nursery.  In it they break down 
their climate zones listing with recommended zones for the south and for 
the west.  For example, Hosta 'Guacamole' is listed hardy for zones 3 - 
8 in the south, 9 in the west.
    Catriona Tudor Erler

Miranda Smith wrote:

>Nice to have you here!
>
>Miranda
>
>On Jan 3, 2008 11:52 AM, <blombem@gvillesun.com> wrote:
>
>  
>
>>Hi all: I've been reading posts for two years now, and hope to get
>>involved
>>in the discussions. I have been writing a garden column for The
>>Gainesville
>>(Fla.) Sun for nearly 35 years (it's a side job from my "real job" as a
>>reporter and editor) and have noticed there aren't many 8b'ers on this
>>list
>>(except for those of you in California -- that's an entirely different
>>zone
>>8b than ours; we have humidity).
>>
>>If this goes through, then I have broken the barrier.
>>
>>Marina Blomberg
>>
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>>    
>>
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