An increasingly warm climate means — among other things — the chance to grow new plant varieties previously unheard of.
The Pacific Climate Impacts Consortium predicts a two-degree increase in temperature and 20 more frost-free days by 2070.
But warmer winters are already being felt in garden beds across southern B.C.
Gardening expert Wim Vander Zalm, who owns Art Knapp nurseries in Port Coquitlam and Vancouver, believes the Lower Mainland has changed from a Zone 7 to a milder 7B, a designation based on plants’ hardiness.
“For the past 10 years for sure, it’s been getting increasingly warmer. There’s been one winter in there (2008-2009) that was bad. But the past 10 winters have been very mild.”
“We kind of moved up half a zone, and that makes all the difference,” he said. (He admits it’s an “arguable point.”)
Even some subtropical and Mediterranean species such as lemons, olives and figs can now survive the winters outdoors, and Knapp estimates in the last five years, sales of such new-to-B.C. plants are growing at 20 per cent per year or more.
“It used to be you couldn’t definitely grow them. Now they are growing and surviving,” Vander Zalm said.
While enterprising gardeners might have overwintered a fig tree in the past, citrus and guava plants would never have survived a winter outdoors, he said.
And while innovative gardeners have been using microclimates like greenhouses to grow and produce persimmons, Asian pears, quinoa, amaranth, kiwifruit and goji berries for years, according to University of B.C. horticulturalist Douglas Justice, growing lemons in the backyard is relatively new.
“We’re on the cusp of these bigger changes, but the changes haven’t been that profound yet,” he said, warning climate adjustments may not affect the south coast as much as the Fraser Valley, the north and interior, where unpredictable weather, drier summers and wetter winters could wreak havoc on established growing practices.
In some places it already has, said researcher Erica Crawford of the Pacific Institute for Climate Solutions. Last summer she met farmers in the Delta region who were unable to harvest their potato crops because they were too wet, losing millions of dollars.
At Gardenworks in Burnaby, gardeners are buying palm trees, kumquats and even banana plants. But winterless winters have a serious down side.
“It sounds charming. It could be a nightmare,” said Kent Mullinix, a sustainable agriculture and food security professor at Kwantlen University.
“Folks need to understand our agriculture system developed on millennia of stable climate and predictable weather patterns. Through the 21st century, all bets are off,” he said.
As a pomologist, Mullinix visited Fruit Trees and More Nursery in North Saanich on Vancouver Island, where farmer Bob Duncan grows a lemon tree bearing hundreds of lemons a year, something Duncan attributes to warmer winters. The tree is sheltered but lives outside. Mullinix is doubtful real lemon groves will pop up on the south coast, due to the significant horticultural skill required, but says climate change will bring “all sorts of changes in the patterns of what crop plants we can grow where.”
In B.C., the crop range could expand with milder winters — we could be growing produce in the Peace region, wine grapes in the North Okanagan, and more eggplant and tomato in the Lower Mainland. Cool-weather plants such as salad greens and cruciferous vegetables could be reduced.
Olea leccino (olive)
In the Gulf Islands, the Saturna Olive Consortium imported over 500 olive trees from California and now has a thriving grove. “The first year we brought trees in we had a mild winter, and the second we had a harsh winter. It knocked some trees back and in other locations it didn’t do anything,” said owner Michael Pierce. They typically grow in the warm temperate or tropical climates of south Europe and Asia.
Acca sellowiana (pineapple guava)
A smaller variety but hardy for our climate, the pineapple guava is native to Latin American countries such as Brazil, Colombia and Argentina, and can be grown in tropical, subtropical or warm-temperate climates. Fruits are about the size of an egg and mature in autumn.
Citrus — orange and lemon
“It’s kind of cool to have citrus on your patio or a sheltered spot in your yard. But also the fragrance from the orange and lemon blossoms are spectacular,” making them popular among adventurous gardeners, Vander Zalm said.
Originating in Southeast Asia and typically found in sub-tropical climates, citrus fruits are gaining favour with farmers on Vancouver Island. They generally cannot withstand prolonged winters colder than -2 C.
Ficus carioca (common fig)
“There used to be only two varieties of figs we could grow. Now there’s about six,” Vander Zalm said. Thought to be the first plant to be cultivated by humans, the common fig is native to the Mediterranean region and the Jordan Valley, and cannot survive persistent sub-zero temperatures. The garden centre expects to sell at least 100 this season.
Camellia Sinensis (tea)
“Camellia Sinensis is what they grow in India and Sri Lanka and China,” said University of B.C. horticulturalist Douglas Justice. “That’s probably not a bad indicator of how much warmer it is.” An operation called Teafarm in the Cowichan Valley planted 200 tea shrubs since 2010 and 199 of them survived. “For us it’s an experiment. We wanted to see if they would take,” said co-owner Margit Nellemann, who wants to explore the commercial possibilities of 100-mile tea.