Re: Zones
Glenn wrote:
>Might I make a plea for all contributors to this posting, to include
>somewhere in their signature, what the relative climatic zone they live in
>is. I read some very interesting information but some times am not too sure
>of its applicability to my situation.
Problem is Glenn, that whilst USDA zones may prove applicable in
continental type climates, they do not really apply to those with a
strongly maritime climate. The debate about the validity of zones has
erupted on many occasions here in the UK this year and the general
consensus is that they cannot be applied here due to the extreme
multiplicity of microclimates and very peculiar nature of our weather.
Technically I live in a Zone 9b area, but my summers are closer to 6
and more similar to those found at the northern limits of the PNW. In
our case, we are as far north as Labrador, but the gulf stream keeps
us artificially warm. Here we are in the odd position of being able
to grow some things which should not do at all well, but fail
abysmally with others that tolerate far colder winters than we have
ever seen here. It tickle me that some describe their winters as
being quite mild with temperatures *only* dropping to 20 or 18F. To
my mind that is exceptionally cold and a once in 20 -30 year event
here.
Zones only indicate minimum temperatures, but give no
information about anything else. Plant hardiness is not just to do
with minimum temperatures, it is to do with how long those
temperatures persist, the variation between highs and lows on any
given day, the amount of free moisture available at the low end of the
scale and light intensity. I have had plants sent from the US that
despite claimed hardiness, have refused to grow. Nothing wrong with
the plants that were sent, its just that light levels and the absence
of wide variations in temperature caused them to react as though it
was mid winter even in the middle of summer!
Here we do not see the dramatic hike in temperatures in spring and
there is no sudden jump from days of 7 - 10C maximums to days of 21 -
25C and higher. It is this 'kick' that gets a lot of plants moving
and its absence causes many US raised plants such as Alpinias and
Aroids to remain in their dormant mode. We've seen the same problems
with Musas, Strelitzias and Heliconias as well, so as impressed as I
am with the quality of stock coming out of the US, I have to leave it
well alone and look for European raised plants. This is exceptionally
frustrating for me - especially when I see that the only available
stock of plants such as Setaria palmifolia 'Rubra Variegata' is in the
US and nowhere else. Mind you in the case of that grass, I'd happily
take a chance, but the 'Glasshouse Works' never seem to answer
e-mails! so I'm stuck with the green form - nice but not stunning by
any stretch of the imagination.
You might think from the zoning for my area that we are warmer here
than N. Florida. I'd love that to be the case, but quite obviously
nothing could be further from the truth. Our minimum temperatures are
certainly higher than those experienced there, but our daytime highs
never rise by the same degree. Therefore we often get nights falling
to no lower than 5 or 6C where Florida might be seeing light frosts.
However during the day, we often only see a slight rise of 3 or 4C to
around 9 or 10C., whereas in Florida, those cold nights are followed
by days reaching anywhere between 14 - 20C or even higher. These
jumps. plus the spring time temperature 'hike' are not indicated in
the zoning and plants with a Zone 7 or 8 designation could easily fail
here. I used to add the USDA Zone to my postings here and elsewhere,
but in my case at least, they really mean nothing at all.
Sorry this doesn't really help with your situation Glenn, but from
what I can remember of Cape Town, although it is right on the coast
and should in theory be a truly maritime climate, it seems to have a
more continental type suggesting that in your case, zoning might be
more reliable.
Dave Poole
TORQUAY UK
http://www.ilsham.demon.co.uk/gardenviews.html
