Southern magnolias, lovers of sultry weather, braving the
chillier Northeast?
Camellias, a New Orleans trademark, staking out in North
Carolina and higher latitudes?
It's true, gardening experts say, and expect similar
oddities to represent the new norm.
It is now safe to plant new species in many parts of the
nation, according to a new government map released Wednesday showing new
growing guidelines for the first time in decades. A gradual northward warming
trend makes it possible to plant trees and other perennials that would have
perished in colder zones. The "hardiness" zones, the gospel to the
nation's 82 million gardeners that are printed on the back of seed packs and
catalogs, are based on average minimum temperatures.
"It is a good thing the government has updated the
map," says Woodrow Nelson, director of marketing communications for the
Arbor Day Foundation. "Our members have been noticing these climate
changes for years and have been successfully growing new kinds of trees in
places they wouldn't grow before."
For example, Pennsylvania's growing zone was considered
risky for southern magnolias, according to the old government map dating to
1990. But the new map, based on updated weather statistics from 1996 to 2005, puts
Pennsylvania, like much of the Northeast, in a warmer growing zone.
Catherine Woteki, an undersecretary of the Department of
Agriculture, which issued the new guidelines, cautioned against reading too
much into the changes. "We do not think the plant hardiness zone
methodology is appropriate for making comments on climate change," she
says.
Might gardeners be going out on a limb? Steve Carroll,
director of public programs at the State Arboretum in Virginia, advises
gardeners to check with their local nurseries or a university extension program
for advice.
"There's definitely a changing climate," says
Charlie Nardozzi, a gardening consultant in northern Vermont. "But that
doesn't mean we won't have a harsh winter again that could kill all their
plants."
