Today's NY Tmes has a very interesting article on the upcoming revised hardiness/heat zone designations for plants.

http://www.nytimes.com/2002/11/07/garden/07NATU.html
(The article in the Times is free, but you do have to register to access it.)

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New Yorkers used to know to grow salvias as annuals and to take that bay tree inside for the winter. Now, fuzzy kiwis, Italian cypresses and cannas too tender for Northeastern gardens, according to the Agriculture Department's Plant Hardiness Zone Map are lounging around New Jersey and Connecticut and Brooklyn. The hardiness zone map, first created in 1960, told people
the average coldest temperatures of their area.

Although it was updated in 1990, the map had become so outdated that the American Horticultural Society, with a $70,000 grant from the Agriculture Department, is updating it again. They are adjusting the official zones to reflect warmer temperatures and in a few cases, cooler ones. ...

Eventually the heat map and the new zone hardiness map will be joined and available on the Internet. Although you won't be able to zoom in on that south-facing wall in Brooklyn, you might be able to find the microclimate of your city. "Cities are holding heat, so they are going to be warmer than surrounding areas," Kim Kaplan of the Agriculture Department said. Next year, Ms. Warner said, gardeners will be able to go to the American Horticultural Society Web site (www.ahs.org), type in their ZIP codes, and come up with "a list of the 25 toughest plants for that area."

And surprise: the new hardiness map has added four new zones on the tropical end of the scale. Zone 15 includes plants hardy only down to 80 degrees. None of the four new zones (12 through 15) will show up on the hardiness map of the continental United States, but Hawaii will have Zones 12 and 13. You may see the highest zone numbers (14 or 15) on the label of that tropical banana plant you bought. Global weirding or no, if you live anywhere other than South Florida, you're still going to have to put it in your glass conservatory for the winter...>>>>

From American Horticultural Society
http://www.ahs.org/publications/heat_zone_map.htm#2

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Many of the plants that we consider annuals-such as the petunia, coleus, snapdragon, and vinca-are capable of living for years in a frost-free environment. The Heat Map will differ from the Hardiness Map in assigning codes to "annuals," including vegetables and herbs, and ultimately field crops as well.

It will take several years for a majority of garden plants to be coded. After almost 40 years, we are still perfecting the zone ratings for the Hardiness Map. Plants vary in their ability to withstand heat, not only from species to species but even among individual plants of the same species! Unusual seasons-fewer or more hot days than normal-will invariably affect results in your garden. And even more than with the hardiness zones, we expect gardeners to find that many plants will survive outside their designated heat zone. This is because so many other factors complicate a plant's reaction to heat.>>>

I'm pretty certain that my garden is showing some of these trends. Most of the leaves are still on the trees here. I haven't had any real frost yet. The calendula, and strawberries are putting out fresh flowers.The peppers, radishes and carrots are still going strong.

Sy