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Cold-Adverse Plants Warm Up to a New Home

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Cold-Adverse Plants Warm Up to a New Home

Cold-Adverse Plants Warm Up to a New Home

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STEVE INSKEEP, host:

And let's continue with our series, Climate Connections. NPR and National Geographic have been traveling the world, finding out our climate is changing people and places. And this past month, we've been focusing on the South Pacific. This morning, we're going to meet a plant from New Zealand which is now growing in our own backyard. You may wonder how am I going to start a conversation with a plant, but not to worry, because as part of our series, NPR senior correspondent Ketzel Levine will make the introductions. She begins with a brief horticultural tour.

KETZEL LEVINE: With apologies to most of the country, we gardeners in Portland, Oregon are spoiled rotten. Our temperate climate enables us to grow a glut of the world's plants.

But simply listing where they're from doesn't really cut it. I'd rather you imagine walking through a garden where each plant plays its own native tune.

(Soundbite of music)

LEVINE: You're now looking up into the pendulous arms of a graceful pine from Hunan, China. As you walk along, you stop to rub the peanut-butter scented leaves of a shrub from South Africa.

(Soundbite of music)

LEVINE: And now, soaking up the sun, you see three small shrubs with different color foliage, all singing the same song.

Ms. FIONA EADIE (Head Gardener, Larnach Castle): The song of the hebe. The sound of a hebe would be something wistful. I think of flute.

(Soundbite of music)

LEVINE: From the lonesome, drizzling cliffs and green tufted grasslands of New Zealand, introducing the hebe - spelled H-E-B-E - and the gardener who delights in its native wistful faces, New Zealander Fiona Eadie.

Ms. EADIE: The thing about hebes is is that they come in just so many different shapes and forms. You can get groundcovers. You can get little bushes. You can get small trees. And you can basically just about get a hebe in whatever color foliage you like.

LEVINE: Hebes are most at home in skree, rocky soils with fast drainage. They don't mind heat, but they loathe humidity. What they adore, says Fiona Eadie, is the wind.

Ms. EADIE: They nestle under the ground. They just nestle onto their environment. You get the best-looking hebes in the harshest conditions.

LEVINE: But harsh in New Zealand means winter lows well above zero Fahrenheit. Some of the showiest hebe expire at 17 degrees, which explains why the genus has been a heartbreaker here in the Pacific Northwest, where, until recently, only hardcore plant nerds risked loving and losing the plant.

Things have changed. Just yesterday, I saw a hebes growing happily at a local community college. And each week, it seems, our nurseries are pushing new species and cultivars.

What's different is this: We now know a lot more about the hardiness of different hebe species - hardiness is a word typically used to describe a plant's tolerance for the cold. Hebes are particularly happy these days because winters of late have been warmer.

And it's not just here in Oregon. Gardeners across the country now report growing plants they could never get away with before.

Mr. TONY AVENT (Horticulturist, Plant Delights Nursery Raleigh, North Carolina): Oh, a classic example for us would be windmill palm, Trachycarpus fortuneii.

LEVINE: Tony Avent can now grow this palm from the mountains of southern China in his celebrated botanic garden at Plant Delights Nursery - Raleigh, North Carolina.

Mr. AVENT: Up till 1996, I would consider those very marginal in our area. All of a sudden, they're almost completely reliable in our climate. Eucalyptus, now that the climate is warmed, we certainly can grow quite a bit more.

LEVINE: And, a bit less. Good old-fashioned peonies are said to be struggling now in Raleigh, bereft of their invigorating winter cold.

Tony Avent likes to brag. He considers every plant hardy until he's killed it himself three times. There is a safer way to go - the Plant Hardiness Zone Map, published by the USDA, a tool gardeners use in selecting appropriate plants.

The map divides the country into lasagna-like layers of different colored hardiness zones, each zone determined by a region's average lowest temperature.

Mr. AVENT: And this is a map the most current crop of gardeners - the baby boomers - have grown up with is a 1990 map.

LEVINE: That 1990 map was based on a dozen years of data - 1974 to 1986 - a period which turns out to be colder than any since, which means the USDA map, that holy writ of hardiness, has made us unwittingly cautious growing plants well within our range.

As for a new hardiness map, well, project consultant Tony Avent says it is in the works and might be out by year's end. He could reveal no details, but did say it would reflect three decades of data and will confirm what hebe lovers already know.

Mr. AVENT: The new map that will be coming out will certainly reflect that it's getting warmer. I don't think there's no question about that. We can grow plants that we could never grow back in the '80s pretty reliably as long as people aren't surprised when we get a cold winter to come in and knock things back.

(Soundbite of music)

LEVINE: Neil Bell, are you out here somewhere? He's about five rows of big, delicious hebes away. We've come to Neil Bell's outdoor Oregon laboratory, at one of the state university's research centers, where, for the past seven years, he's been growing and losing hebes to determine how they will perform in our climate.

Mr. NEIL BELL (Horticulturist): The Achilles' heel of hebes is that many of them, particularly the showier ones that bloom in the fall, well, they'll just keep growing and blooming happily as long as it's relatively mild. And, of course, when we get those cold spells, they happen really suddenly and the plants aren't prepared for it.

LEVINE: What he's learning about the genus in his hebe hardiness trial may -plant by plant - eventually alter the look of this (unintelligible) valley landscape.

Mr. BELL: This one I like a lot - Hebe corriganii. And this one will just cover itself with flowers.

LEVINE: Now a few thousand hebes flowering in Oregon does not mean the Pacific Northwest fancies itself the new South Pacific. But we have reached a point where prejudices like that, that won't grow here may deny our chlorophyllic friends a port in the storm.

With the climate changing globally, native plants from one part of the world could find themselves seeking shelter in another, and the hebe may someday need the global gardens of Oregon for this lyrical species to thrive.

Ketzel Levine, NPR News.

INSKEEP: Now if you'd like a little lyricism in your life and a port in the storm, you'll be able to talk plants with Ketzel Levine in her new blog, npr.org/talkingplants, and there's more about climate change in this month's National Geographic magazine.

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