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Pushing the Zones

Don Nicholson

Do you know your gardening zone? Do you care? Perhaps you are one of those gardeners who lives in "zonal denial". To you it doesnít matter if your banana plant doesnít survive the Peterborough winters.

However, if you are the cautious type, you donít want to unnecessarily subject your plant to conditions they donít like; you want them to live happily through your cold winter or hot summer and be at home in your garden. You donít want to waste a lot of money and time on plants that arenít going to survive and have to be replaced year after year.

A hardiness zone is a specific geographical area with its own set of environmental conditions, and a hardiness zone map is a map showing the geographic boundaries of the different zones. The American hardiness zones are based strictly on temperature, whereas the Canadian hardiness zones are based on minimum winter temperature, maximum summer temperature, length of the growing season, summer rainfall, wind and snowcover. Note that we Canadians as a general rule need to add one number to the American zones to get the Canadian equivalent. I ALWAYS check the plant tags where I purchase my perennials, shrubs and trees for the zone number and I ALWAYS check to see if the plant has been imported from the U.S. and might be using American tags.

Bancroft is Zone 4a, Peterborough is in Zone 5a, Port Hope is 5b and Toronto is 6a. The lower the number and letter of the alphabet, the colder it gets in the winter. As a general rule of thumb for growing seasons, there is approximately a two-week difference between zones and a one-week difference between sections "a" and "b" within zones. Do you ever hear people coming down from Haliburton or Bancroft say, "You people are two weeks ahead of us with the leaves coming out on the trees" or "The ice isnít even out on the lakes here."

Iím a bit of an adventurer, but semi-frugal (selectively cheap) at the same time. Iím not willing to throw my money away trying to grow plants that Iím certain will not survive our cold winters, but I am willing to experiment and "push the zones" by 1 or maybe even 2.

Microclimates exist within your own personal garden zone. For example, a sheltered spot protected from cold northern air, such as against a warm south facing-wall, can be a zone or two warmer than exposed areas on the north side of the house. This would be a good spot to grow plants that are only marginally hardy for your zone by protecting them in this sheltered spot. So, if you live in zone 5, but your really, really want that tender plant designated for zone 7 (St. Catherines/Niagara Falls) or warmer, you can go ahead and try it in a sheltered spot. Remember, zone systems arenít always 100% accurate, so you may be surprised what you are able to grow in your garden. Two or three winters ago, the low snow cover and extremely low temperatures had people cutting down dead trees, and digging out dead shrubs that had withstood years of Peterborough weather. Then too, we had a silver lace vine growing over the pergola on our back deck that did not survive the winter and yet all our perennials directly below it that were protected from the strong, cold north west wind survived.

We have an 18 inch deep pond in our backyard. Iím too lazy to bring in the water lily or goldfish. I purchase a floating heater that is thermostatically controlled, the type that keep a hole in the ice in cattle troughs. It was interesting to watch on a sunny day, the goldfish "slowly" swimming under the ice near the hole.

Having lived near Lake Erie, the northern boundary of the Carolinian forest, I was fascinated by the tulip trees growing in the area. Iím speaking of the "Liriodendron" and not magnolia. This tree can grow in the proper environment to be 100 feet tall. It has lovely, stylish leaves and tulip-shaped green/yellow spring flowers. About 14 years ago, a Peterborough friend of mine brought me one from the Lake Erie area and it is now about 32 feet tall. Perhaps this will be the year it will bloom.

I have planted what I call "swamp" cedars at the back of our property (not as a hedge) to act as a buffer against the west winds.

When pushing the zones, as well as considering sheltered areas away from the cold, drying winter winds, I plant deeper. I always make sure that I provide good winter drainage. I have lost more shrubs, not from the cold temperatures per say, but from the drying winter winds. I have learned to water my shrubs well in the fall, not for growth, but to add extra moisture to the evergreens. Some I have even began to cover with burlap. Rhododendrons can sometimes be tented with thin pieces of plywood or boards to protect them from wind and heavy snows that will break the limbs.

So, donít give up, if there is something youíd really like to try growing but think our weather is too cold or too harsh, try growing it. You all know your sheltered areas around your home . . . and if you donít have one, make one. Be daring, be adventuresome!

Have fun, but be reasonableódonít expect your banana plants to survive outdoors in a Peterborough winter.