On 21 Feb 2003 08:40:36 GMT, (Nick Maclaren)
wrote:


Rodger Whitlock writes:

...The USDA zones were devised with
a specific purpose in mind, hardiness of *woody* material in the
continental USA.

Perhaps I am too stringent, but I regard anyone who invents such
a scheme without thinking of its potential for extension as being
a fool...at the very least they should have considered
its relevance to herbaceous crop plants.

Not really (imo). The only important herbaceous crop that
over-winters, and for which hardiness is therefore an issue, is
fall-sown wheat, afaik. The other big grain crop grown in the US
is corn (maize), which is invariably sown in the spring.

And it may be that the deviser realized that a system suitable
for herbaceous material was impractical as their hardiness
depends on many other factors than just temperature, whereas the
hardiness of woody material (sc. fruit trees) is really dependent
only on the winter low temperature.

Horticultural material doesn't have enough economic importance to
count in this kind of study.

--
Rodger Whitlock
Victoria, British Columbia, Canada