We are joined by Helen Battersby, a Toronto garden blogger, garden coach, and publisher of the Toronto & Golden Horseshoe Gardener’s Journal.
Battersby talks about the difference between the Canadian and American garden zone systems—both of which provide gardeners with a zone number to use when selecting hardy plant material. The lower the number, the colder the garden zone.
She points out that while her garden is a zone 6 using the Canadian system, it’s a zone 5 using the American system.
The Canadian system uses a number of variables including lowest mean temperature of the coldest month, highest mean temperature of the hottest month, precipitation, and the number of frost-free days.
The American (U.S. Department of Agriculture, or USDA) zones are based solely on average annual minimum temperatures.
She likens the Canadian system to a Betamax; and the US systmem to the VHS.