The Zones are on the move.

Gardeners rely on the idea of fixed zones, based on annual average low temps, to determine whether a plant or a tree will be hardy enough to live in their garden. Kingston, RI, for examle is Zone 6. New Orleans is Zone 9.

The Zones are having to be redrawn. The Arbor Day Foundation recently redrew their zone maps, and there's an animated transition between the 1990 and 2006 map that really takes your breath away. There people have no political agenda, they just want you to be able to find trees and plants that will live in your garden, and those trees and plants are changing, rapidly. Many Zones changed by 1, some changed by 2. Cape Cod jumped from 5 to 7 - that's the climatological equivalent of moving from Southern Maine to Northern Mississippi.

This article describes what these changes mean for New Jersey gardeners "Goodbye, Douglas fir and white spruce. Hello magnolia and stately southern oaks. "

Washington DC, too has changed: ""You could say D.C. is the new North Carolina," said Bill McLaughlin, a curator at the U.S. Botanic Garden on the Mall."

"In sections of Michigan, the weather was warm enough to suit southern magnolia trees, said Arbor Day Foundation spokesman Woodrow L. Nelson. The southern species Arizona cypress also seemed to be better adapted for some parts of the Northeast, he said."

In the UK, changes in climate are steering many gardeners towards planting Mediterranean plants such as lavender, rosemary, olive trees, and so on, that are drought resistant and love long hot summers and mild winters. Soon when people talk about an English cottage garden, they might be picturing something that doesn't exist anymore- so long to the lupines, the primulas, the foxgloves- all plants that need a winter chilling period to perform. Also, droughts in the UK led to extensive bans on outdoor watering, leading, last year, to what must have been a crash in hose sales: "Sales of hose pipes were down: in the country, by 25%; in the south-east, by 76%."