Grow Olives in Cold Climates
By Steven Biggs
Growing Olives in Canada
Olive trees don’t survive winter temperatures in most parts of Canada…but there are creative ways to grow them.
As Bob Duncan points to the south and west walls of his house he tells me, “Don’t waste them on rose bushes!”
Duncan is near Victoria, British Columbia. And against these south and west walls he grows olive trees (Olea europaea).
While olive trees don’t survive winter temperatures in most parts of Canada, in the balmier parts of British Columbia they do.
“The trees are absolutely fine at -10°C,” says Duncan, owner of Fruit Trees and More nursery.“
Last year that one was thick with olives, thousands of them,” he says, pointing to a 10-year-old tree.
It’s not surprising that olives do well here, says Duncan. He explains that they are grown extensively in the Mediterranean basin, where winters are similarly cooler than summers.
Growing Olives in Southern B.C.
Bob Duncan, serving home-grown olives in British Columbia, Canada
Duncan grows olive trees flat against his house on a series of horizontal wires. If temperatures drop below -10°C (14°F), he drapes the outward-facing side of the trees with a floating row cover (a breathable, lightweight, cloth-like material).
He also has one other trick to protect the trees during cold spells: Old-fashioned incandescent Christmas lights. When temperatures get low enough, he turns on the lights, which emit just enough heat to keep the temperature in a safe zone.
Elsewhere in B.C.
Michael Pierce grows olives in the ground out in the open at his home on Saturna Island, B.C. His nursery, Saturna Olive Consortium, specializes in olive plants.
He says that while the climate on some of the southern Gulf Islands and around Victoria makes it possible to grow in-ground olive trees, it’s borderline.
“They grow more slowly because the growing season is shorter and the conditions are cooler,” he explains.
Duncan tells local gardeners not to waste the south- and west-facing walls on their property on roses…save them for olives!
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Even if you live somewhere too cold for olive trees to survive the winter, you can enjoy the exotic touch of an olive tree in your garden. This book gives you what you need to know to grow an olive tree in a pot. (And get olives!)
If temperatures drop low enough, Bob Duncan turns on the incandescent Christmas lights on his olive plants as a source of heat.
Growing Olives in Colder Canadian Climates
My own potted olive trees in Toronto survive winter in a cool sunroom, an insulated garage, and even in my dining room.
A friend overwinters hers by the south window in the house.
Find out more about how to grow an olive tree in a pot.
While they make attractive indoor plants, Duncan and Pierce both point out that without a cool spell, the flowering cycle of the tree can be disrupted. So if you overwinter them at room temperature, you might not get flowers and olives.
Don Moffat, who works as an ornamental gardener in Toronto, has helped clients overwinter olive trees. Smaller trees, he says, can be buried to protect them over the winter.
Duncan notes that while in-ground trees easily withstand -10°C (14°F), potted trees should be exposed to no more than a light freeze. “The roots are not as tough as the upstairs,” he says.
Getting Olives to Flower and Fruit in Canada
My original two olive trees—clones from the same plant—looked great but didn’t fruit for years. Duncan explained that they likely needed a cold spell. So I tweaked my overwintering technique to give them cold, bright conditions over the winter in a minimally heated greenhouse.
Duncan also explained that because my plants are both the same variety, and because olives are not usually self-fertile, I should get another variety.
My Toronto olive harvest!
While Duncan has seen plants in isolation produce some olives, “It’s better to have two varieties,” he says.
So I got a third olive tree—another variety. And between having two varieties, and providing a cold, bright spell over winter, my olives began to flower and set fruit.
Olive Pollination
“There is pollen everywhere,” says Duncan, as he talks about knowing when to help pollinate his olive trees, which are wind-pollinated. He uses a feather duster, or a vacuum set on reverse to blow.
I let nature take its course, and don’t help with the pollination of my olive trees.
Olive Harvest
Pierce usually harvests olives in November. Harvest time depends on the growing season, the variety, and stage of ripeness.
Olives can be picked green, when they start to turn colour or when fully coloured. The fruit can’t withstand temperatures as cold as the tree.
Maintaining an Olive Tree
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Olive trees do best in full sun. When grown in a pot, use a well-drained potting mix and feed with a balanced fertilizer in spring and summer. Keep potted plants well watered, but not constantly wet: Duncan advises that they be kept on the “dry side of moist.”
A young tree might need support until its stem thickens. Prune in spring to obtain the desired size and shape, removing crossing branches. Olives grow into small trees. Duncan’s reach up to the eaves of his house.
The size of potted plants is determined by the gardener. My own olive trees are in 14” pots; I prune the plants to six feet in height so they are easily carried through a doorway.
Plants that are grown from cuttings (as are most commercially available plants) are “physiologically” mature and will fruit while still small. Pierce says, “I’ve seen little, twelve-inch trees start to flower and get fruit.”
Olive Varieties
There are many olive varieties, and some are more tolerant of cold than others, says Duncan. Pierce finds the cultivars Frantoio and Leccino have good cold hardiness.
But for gardeners growing olives in pots and providing a protected spot for the winter, this cold hardiness is not as important as it is for people growing olives in the ground in southern BC.
My original two olive trees are an unnamed variety with olives that are large, plump, and green when I pick them here in Toronto in October. My third olive tree, which came home in the suitcase from Bob Duncan’s nursery, is a Frantoio, and it’s smaller olives are just starting to colour up as I pick from my olive trees before stowing them away for the winter.
More on Growing Olives in Cold Climates
Find out how to grow an olive tree in a pot.
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Here’s More Exotic Fruit You Can Grow
If you get a kick out of growing things where they don’t normally survive, find out about how to harvest figs and lemons in cold climates: