What zone are you in?

When my brother-in-law lived in Edmonton, Alberta, my husband used to tell him he lived in "the frozen tundra of the north", so I suppose it serves us right that we would eventually live here, while the brother lives on the lovely West Coast. Agriculture Canada rates Edmonton as Zone 3a, which means our summers are short and our winters are long and cold. As harsh as the seasons seem, though, it doesn't get much better than this on the Canadian Prairies, unless you live in Taber, Alberta, which is squarely in Zone 3b, or Lethbridge, which borders onto Zone 4a. But Calgary is another Zone 3a location, and Winnipeg and Saskatoon are both 2b. Regina is even more difficult at Zone 2a, and Fort McMurray is Zone 1a. Very few plants are rated hardy to zone 1, but maybe they just haven't been trialled that far north. If you'd like to check what zone you are gardening in, check out Agriculture Canada's interactive map. The USDA Plant Hardiness Zone Map has less detail for Canada, but is much more helpful for Americans (obviously). 

Of course, these zone ratings don't take into account microclimates that some gardeners can take advantage of. Many urban gardeners can take advantage of the heat island effect, where the day temperatures are higher because of the heat from cars and buildings. Buildings and paving absorb this heat and radiate it back at night, so the night temperatures also tend to be higher. Urban gardeners benefit from this to different degrees, however. Temperatures in the downtown core might be significantly higher than those by a park or on the edge of town. However, if you live in a large city, many experts seem to agree that you can probably grow plants rated for one zone higher than yours. (Many of these same experts also seem to think that the zone ratings listed on many plants are either inaccurate or just plain guesses, too.)
Other microclimates might occur in your garden that will expand or restrict the types of plants you can grow. A sunny, sheltered spot might get you another increase in zone, but an exposed location, or one at the bottom of a hill where frost will linger on a cold night, might kill a plant that is rated for your zone. Locations with good snow cover will also overwinter plants better than ones with only sporadic snow, which means that those who live in areas prone to snow-melting Chinooks may have more difficulty than gardeners whose winters are colder but snowier. That is a lot to think about, but usually the best strategy is just to ask staff at a local garden centre or to find out what your neighbours are growing. 

And if one of my lovely perennials doesn't make it through the winter, I just ask myself, "Who wants to grow such a fussy plant, anyway?"

1 comment:

  1. Interesting that the US site is about ways to ameliorate the heat island effect. As usual, the Yanks have a problem recognising a good thing (the Southerns get a pass, though, since they get too much of a good thing).

    I have a recurrent envy problem with my friend at Gardening Zone 3b who lives near the City Centre airport in Edmonton and has consistently earlier bloom times, an earlier end to Spring frosts, and later and less severe Fall frosts. I live about halfway between the City Centre and the International airports and my backyard temperatures are consistently intermediate. Oh well, at least we didn't end up in Nisku.


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