Re: cold, hardiness, and lies :)

--- Barry Garcia <barry_garcia@csumb.edu> wrote:
> 
> I've been reading descriptions of various
> sub-tropical to tropical plants
> that most sources claim cant take temps much below
> freezing, and yet i see
> these plants in my town. For instance, Strelitzia
> reginae , i've seen all
> over my town, and is sold in nurseries here, and
> i've hardly seen any
> freeze to death, even in the open. Same with S.
> nicolai (one of the yards
> in town has several along a wall). I refuse to
> believe that theyre that
> tender.

Barry,
In defense of Sunsest's generally conservative
climatic ratings for plants, they play it safe for
many things like Strelitzia species based on the
average temperatures for each zone over 20 year
periods.  Do not forget that we can get those arctic
killing freezes even here along the coast every 10 to
20 years, and have had two bad years as recently as
winter of 1990 and 1998 in the San Francisco Bay Area.
 My one year old garden in Berkeley looked like it had
been hit by a blow torch the week before Christmas,
and water remained frozen an inch thick for all ten
days of the freeze here in Berkeley.  By 1998, I had
been lulled into complacency by a series of mild
winters, and was surprised to find ice cycles one
morning on all my Tillandsias planted epiphytically on
my Japanese Plum tree, (I had not turned off my mist
system, thinking that ice protection would insulate
them, and learned again the hard way).  Even balmy San
Diego got cold enough to kill many supposedly hardy
plants in their sunset zones 23/24, USDA zones 9/10,
with most things surviving in zone 11, except where
people had wildly pushed the envelope with even more
tender tropicals.  

I agree with you that many common things like
Strelitzia are perfectly hardy here if one is willing
to suffer the occasional damage, cover to protect them
in freezes, etc.  I am more inclined to risk growing
smaller growing plants, or those which will return
from the roots such as Brugmansias and Iochromas, but
large palms and trees such as Strelitzia nicholii,
Archontophoenix or Roystonea here in the Bay Area,
outside sunset zones 16/17 are a definte risk, and are
you willing to lose something that gets over 15 feet
tall?  S. nicholii will come back from the roots, most
palms will not.  It is mostly a judgement call, and
all the points mentioned by Tim and especially Ernie
play a role as well.

As the latest winter issue of Pacific Horticulture
Magazine mentions, coastal California is a good match
for tropical montane, mild temperate and mediterannean
climatic areas around the world, and I find I have
greater success with growing the tropicals than many
of the heat and sun loving mediterannean plants in my
local climate.  Especially along the coast, you would
be surprised how many of our commonly grown plants
come from the Andes, Himalayas, mountains of Mexico
and Central America and Southeast Asia, etc.

As to your local area being warmer than you think it
is, I am always surprised at your references to local
low temperatures there in Seaside, just as I am at
Nan's in San Diego.  Are you at the mouth of a local
cold air draining canyon similar to Nan's situation? 
In a zone 17 location, you are in one of the mildest
winter climatic zones that exist in northern
California, yet you seem to get regular frost in your
location.  I do remember that the one winter I spent
in downtown Santa Cruz seemed far colder than nearby
San Francisco, and the night time cold air draining
off the Santa Cruz Mountains explained it.  This
seemed to be more distressing to me than the local
plants, however, as many subtropicals thrive in Santa
Cruz.  The only local neighborhoods that were anywhere
near as mild as most of San Francisco were the sunny
foothill slopes or immediately along the ocean, most
everywhere else was colder at night.  The compensating
advantage was the southern orientation of the coast
line and balmier winter day time temperatures.  If you
are truly keen on the subtropical look, I'd suggest
that Santa Barbara or San Diego are better locations,
as they have the higher winter day time temperatures
necessary for many of the winter blooming species. 
Even the inland Huntington Botanic Garden which can
usually get frost, does better with many subtropicals
which need a certain minimum amount of heat units to
bloom, which we often don't get here in coastal
northern California.  A couple of examples of this
come to mind, such as Eranthemum pulchellum and
Odontonema strictum, both of which grow well here in
Berkeley, but do not bloom in my garden for lack of
enough late fall into winter heat, I suspect.  The
warmer fall/winter temperatures of southern California
also push the blooming season forward by one to two
months for many things compared to northern
California.  

My suggestion for increasing the odds with tender
subtropicals is to pay close attention to
microclimates in your garden, and create conditions
that increase your odds of success; like adding trees
for cover, heat absorbing masonry walls and pavement
and orientation to south/west for maximum heat gain,
and efforts to reduce our regular afternoon winds with
screens, walls and using building orientation/mass to
proper advantage.  Not much you can do about the fog
or your area's absolute lows, but hardening off plants
in late summer by limiting fertilizing, and "goosing
them" again in spring, is a good general prescription
for handling subtropicals in mediterannean climates,
and improving drainage characteristics so that you
don't rot things out with our winter rains.  This is
especially important with plants coming from summer
wet/winter dry subtropical or montane tropical
conditions.    


__________________________________________________
Do You Yahoo!?
Make a great connection at Yahoo! Personals.
http://personals.yahoo.com
Other Mailing lists | Author Index | Date Index | Subject Index | Thread Index