From: Tony Avent tony at plantdel.com> on 2002.03.12 at 15:17:44(8281)
MBurdack:
You are correct that plants from warmer areas will never achieve their
full "potential" in colder zones. We are only interested to know if they
will survive and look acceptable in the garden. Many plants such as
Musella lasiocarpa and Musa basjoo are both from Asian high elevations
climates, but perform beautifully in our warmer climates.
Conversely, many of our bananas will actually fruit, but they are killed
to the ground each winter. While this may not constitute thriving to a
Floridian, this is perfectly acceptable here. What has proved interesting
is that many plants that are hardy here that have not proven so in north to
central Florida. In our climate, a fall cooling period causes many plants
to go into a dormant state that is usually not the case in more southerly
climates. Once plants enter this induced dormant state, they are able to
withstand much colder winter temperatures.
Regarding thriving, we have a Blechnum fern that we collected in Mexico
several years ago. While it returns very late every year, it never gets
very large or vigorous and just limps along. Despite the fact that it is
growing in zone 7, I consider this a zone 8 plant. For us, a plant that
simply limps along is not adapatable to that growing zone. Other plants
such as Philodendron selloum from zone 9-10 in northeastern Argentina have
performed wonderfully here for 15+ years, despite our long cold winters.
Our gardening philosophy allows us to start with an open mind "We consider
all plants hardy until we have killed them ourselves...at least three
times".
Our collection efforts on this recent trip were focused in a narrow
elevation zone where plants still recieved good summer heat, but also cold
winter temperatures. Obviously, plants below and above these elevations
would stand less of a chance of adapting to our climate.
The hardiness map as you correctly point out is only a guide, as nothing
in nature can be pigeon-holed so precisely. Many of us wish that more time
and data had been used to create the USDA hardiness map. Perhaps this will
happen one day.
Tony Avent
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