zoning in the Pacific

Lee Poulsen wpoulsen@pacbell.net
Thu, 14 Feb 2013 22:11:46 PST
Hi Ina,

Those are interesting data pages. Thanks for pointing them out. I'm not sure how they calculated the values, and they may have done as Eugene suggested, which could give the wrong Zone value. (Also, they seemed to have stopped calculating any Zones beyond 11b. There are tropical Zones higher than 11b. And there are some plants that are sensitive to chilly temperatures even if they're not near freezing at all. For example, the palm commonly known as red sealing wax palm, doesn't survive long at all even in Zone 11 climates.) Also, I looked at some other locations around the world and there were a few that seemed anomalous to me (like an island in the Indian Ocean near the equator that was only in Zone 9). Some of the Heat Indexes of some U.S. cities seemed off by one or two values from what they should be.

However, in the case of Wellington, its extreme winter low temperatures may be a few degrees cooler than those of Auckland. But it could still fall within the same Zone since each USDA Zone is a little over 5°C wide. And if you look at the USDA Zone map of New Zealand stored on the Hardiness Zone Maps page of the PBS wiki <http://pacificbulbsociety.org/pbswiki/index.php/…>, you'll see that Wellington is indeed in Zone 10 along with Auckland. 

And for anyone else wondering about New Zealand's typical climate, note that on the webpage Ina cites, it lists both Wellington and Auckland as having an AHS Heat zone of 1, which is the coolest summer zone of all. I may have mentioned this before, but a native New Zealander I knew who lives in the San Francisco Bay Area just south of San Francisco, always complained about how hot the summers were the first few years after moving there from NZ. This seems incredible to most Americans who have visited that area in the summer from other areas. People refer to its natural air conditioning. And I remember many years ago going with some friends to watch a baseball game at Candlestick Park one summer in July or August (typically the hottest time of the year) and we brought jackets and blankets and still felt like we were freezing the entire time. I think Mark Twain was supposed to have said that the coldest winter he ever experienced was a summer in San Francisco. And yet San Francisco is listed as Heat Zone 3 (which is pretty chilly). But you guys in New Zealand have never experienced hot summers as far as I can tell. And yet it virtually never gets below freezing in Auckland. Amazing climate.

--Lee Poulsen
Pasadena, California, USA - USDA Zone 10a
Latitude 34°N, Altitude 1150 ft/350 m

On Feb 14, 2013, at 7:20 PM, Ina wrote:

> Someone sent me this link re zoning around the Southern part of the world:
> http://plantsdb.gr/en/general-cultivation/…
> It is interesting, I agree that Auckland is 10a, but no way is 
> Wellington.  I wonder how the figures compare for Australia?
> Ina

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