Climate Zones.

Rodger Whitlock
Thu, 27 Oct 2005 22:05:36 PDT
On 27 Oct 05 at 17:23, Lee Poulsen wrote:

> ...I have to hand it to the USDA for thinking of the single
> best parameter to use in creating the first Zone map and then
> making the map and seeing what the result was.

The USDA zones were devised strictly, solely to gauge
hardiness of woody material: trees and shrubs. That's all. They
simply aren't applicable to other categories. IIRC, they were
invented at the Arnold Arboretum. Presumably they work not too
badly for their intended purpose -- in eastern North America,
that is!

In particular, the hardiness of bulbs and perennials depends
on many other factors than just winter lows.

And the hardiness zones are of very dubious worth in other 
parts of the planet. They only keep going because Joe Sixpack 
likes things reduced to a single number, no matter how 
misleading it may be.

Rodger Whitlock
Victoria, British Columbia, Canada
Maritime Zone 8, a cool Mediterranean climate

on beautiful Vancouver Island

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