Dartmouth 'being bold' in decision to plant palm trees in this climate
Palm tree climate expert says at least one of the varieties will die
Nine new palm trees are gracing Dartmouth, N.S., parks with a chill, tropical vibe. But a palm researcher said at least one of the varieties won't make it out of a Dartmouth winter alive.
Halifax Regional Municipality planted the palms in Shubie Park, Sullivan's Pond, Ferry Terminal Park and the Dartmouth Common, said Sam Austin, councillor for Dartmouth Centre.
"They're all cold-hardy varieties. They're from either northern climates like Japan or they're from places that have high altitudes like Northern India where in nature they're regularly exposed to snow and freezing conditions," said Austin.
The varieties planted are windmill palm and Kumaon palm — both native to parts of Asia — needle palm, native to the Gulf region and the south Atlantic United States and pindo palm, native to South America.
Austin said most of the feedback he's getting about the palms has been positive.
"Everyone seems to like it. It makes people smile," he said. "It's gone over very well."
"There were one or two who said 'oh, why couldn't you plant a native species?' but I mean the city plants thousands of native species as part of our urban forestry plan every single year… planting nine palm trees is a drop in the bucket."
Needle palm won't survive winter: Palm expert
Researcher and paleobotanist David Greenwood, who studies palms in fossil records and the present day to track changing climates, predicts mixed results.
"I think they're being bold," said Greenwood, a biology professor at Brandon University in Manitoba. "Dartmouth is just on the cusp of a climate that will allow the palms to grow. Still a little cold, but worth a try."
One of the palm varieties they planted won't survive the Dartmouth winter, he said.
"Certainly the needle palm, Rhapidophyllum hystrix — which is from Florida — is going to die, in my opinion," said Greenwood. "I think they're wasting their time."
Others may make it
With a bit of protection, the windmill palm, the world's most cold-hardy variety, and the Kumaon will likely be successful, said Greenwood.
They may struggle in colder than typical winters, he said, and one extreme winter would kill them.
Dartmouth's minimum daily temperature averages –8 C in January.
The windmill palm's leaves are seriously damaged at air temperatures below –12.5 C. The whole plant is killed if its tissues drop to –15 C, he said.
Temperatures have reached record lows below -20 C in the area.
Austin isn't placing any bets on whether the trees will survive the winter.
"We shall see. That one's up to mother nature whether they make it or not."
"We're never going to be planting palm trees all over the place, because they're a lot of work and they're not part of our native environment. But exhibiting some here and there in the parks gives people a chance to see some exotic species," said Austin. "It's just something fun and beautiful to do."
Part of that work for the city's parks department may be wrapping the trees up to prepare them for winter.
Halifax has a tradition of planting exotic species, such as pineapple, coffee and the now-famous agave in the Public Gardens, said Austin.
"I'm happy to have them here. They've certainly got people talking," said Austin.
The trees were purchased from a supplier in Montreal for $2,619.
Canary in the coal mine for a changing climate
In the wild, windmill palms have been spreading north, producing seedlings in regions where the average temperature in the coldest month is as low as 2 C, according to a recent study Greenwood co-authored.
Windmill palms are starting to produce seedlings in Salt Lake City, Utah, outside of the natural range for palms, he said. Cultivated windmill palms are doing well on Vancouver Island and the Vancouver area and within the next 10 or 20 years, he predicts the trees will start growing wild in the forests.
Greenwood said it may take another couple of decades of climate warming before the windmill palm would produce seeds in Nova Scotia.
But with rising record-setting temperatures, he said Dartmouth's experiment might work.
"Palms are the canary in the coal mine they're giving us this signal of a changing climate here in Canada and elsewhere in the world."