January 26, 2012

Maine warmer for plants, but let's not go bananas

The USDA releases a new map that shifts parts of the state to milder zones, giving gardeners more options.

By SETH BORENSTEIN The Associated Press

(Continued from page 1)

click image to enlarge

Manager Jerry Holub looks over seed packages at the Earl May Nursery and Garden Center in Des Moines, Iowa. The government’s color-coded map of planting zones often appears on the back of the packets. Holub doesn’t think the shifting of Des Moines to a warmer zone will have much of an impact there, but it may mean gardeners can try passion flowers.

The Associated Press


For a closer look at Maine's planting zones, go to http://planthardiness.ars.usda.gov/PHZMWeb/# and click on the state.

"Climate change, which has been in the air for a long time, is not big news to gardeners," he said.

Mark Kaplan, a New York meteorologist who helped create the 1990 map, said the latest version clearly shows warmer zones migrating north. Other experts agreed.

The 1990 map was based on temperatures from 1974 to 1986, the new map from 1976 to 2005. The nation's average temperature from 1976 to 2005 was two-thirds of a degree higher than during the previous time period, according to the National Climatic Data Center.

USDA spokeswoman Kim Kaplan, who was part of the map team, repeatedly tried to distance the new zones on the map from global warming. She said that while much of the country is in warmer zones, the map "is simply not a good instrument" to demonstrate climate change because it is based on just the coldest days of the year.

David W. Wolfe, a professor of plant and soil ecology at Cornell University in Ithaca, N.Y., said the USDA is being too cautious and that the map plainly reflects warming.

The revised map "gives us a clear picture of the 'new normal' and will be an essential tool for gardeners, farmers and natural resource managers as they begin to cope with rapid climate change," Wolfe said in an email.

The Arbor Day Foundation issued its own hardiness guide six years ago, and the new government map is very similar, said Woodrow Nelson, a vice president at the plant-loving organization.

"We got a lot of comments that the 1990 map wasn't accurate anymore," Nelson said. "I look forward to (the new map). It's been a long time coming."

Nelson lives in Lincoln, Neb., where the zone warmed to a 5b. Nelson said he used to be in a "solid 4," but now he has Japanese maples and Fraser firs in his yard -- trees that shouldn't survive in a zone 4.

Vaughn Speer, an 87-year-old master gardener in Ames, Iowa, said he has seen redbud trees, one of the earliest blooming trees, a little farther north in recent years.

"They always said redbuds don't go beyond U.S. Highway 30," he said, "but I'm seeing them near Roland," 10 miles to the north. 

Staff Writer Tom Bell contributed to this story.


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