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The Weather
by Liz Primeau
by Liz Primeau

Liz Primeau's second edition of Gardening for Canadians for Dummies, updated and with a new chapter on using art in your garden, plus a design and garden-care workbook section, will be released in January, 2002.

She is at present writing a new book on front-yard gardens, to be published by Firefly Books in spring, 2003.

Liz is the the founding editor of the Canadian Gardening magazine.

April 22, 2001

Everybody talks about the weather. Even though we try not to resort to "Cold enough for ya?", it's still a dependable conversation-starter. I know when my husband is on the phone with his parents in Thunder Bay because his conversation is spotted with phrases like "thirty below, eh?" or "wow--60-kilometre winds!" My son and I spend a good five minutes of our phone calls on the weather, with him lording it over me about sunny January days with temperatures of 74 F. Needless to say, he lives in another country, namely LaLa Land. 
Farmers always complain about the weather and gardeners always worry about it. It was impossible for us to bask in the shirt-sleeve December many of us enjoyed this past winter because we were too busy fretting about the viburnum putting out a few weak blooms, or the lady's-mantle pushing up sprouts months ahead of schedule. Good heavens, is this global warming? Why are our plants out of sync? Are they doomed to die? 
"No matter what the weather is, gardeners always worry," laughs Dr. Campbell Davidson of Morden Research Centre in Morden, Manitoba, a man with a refreshingly easy-going attitude toward the natural world. "I just told people they might as well enjoy the warm weather because they can't do anything about it. They'll probably have a bit more work to do next spring pruning out some dead branch tips, and the plants won't have as much bloom, but those shrubs aren't going to die." 
Plants get ready for winter in three stages, he says. In late summer, when we get less light a day, plants react by shutting down active growth and setting terminal buds for next year. The onset of the first few frosts, the second stage, hardens branches and prepares plants for the third stage: really cold weather, down to -10C or -15 C, and lower; at this point, water leaves the plant's cells and collects in its intercellular spaces. If it stayed inside the cells, it would freeze and rupture them; ice outside the cells will squish them, but they'll bounce back when it thaws. 
Hardy trees, shrubs and herbaceous perennials all go through this dormant period before they come to life again the following spring. Plants that bloom out of season in a warm December, however sparingly, have gone through enough dormancy to allow a few warm days to trick them into thinking it's spring again. "But the branches that bloomed won't bloom again in the spring," says Davidson. "They've shot their wad." 
A couple of really cold days on the heels of the warm ones could freeze the tender tips of the blooming branches, but other than that the plants aren't in danger. "This is what happens in Calgary during a chinook," says Davidson, "although it's more severe there. In the middle of deep cold, a chinook comes out of the mountains, trees and shrubs warm up quickly and start to grow, then they're suddenly dropped back into 20 below temperatures again without acclimating. It may not kill the roots, but it damages plenty of branches." The plants that resist chinooks or warm Decembers best are those normally slow to break buds in spring. "They yawn and stretch, but they don't wake up," says Davidson.
The alternate freeze-thaws of midwinter or early spring, which may heave roots out of the ground, can do more damage than a mild December. And herbaceous perennials that sprout too early are more vulnerable than shrubs. "If their growing tips are damaged, it could hurt the plant a lot", Davidson says. "They need protection. But that's why we mulch, isn't it?"
Even though I'm talking to him on the phone, I can see his mischievous grin. 

Cam Davidson, Morden Research Station, 204/822-4471 ext 201

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