Canada’s most recent Plant Hardiness Zone map takes a wide range of climate variables into account, like minimum winter temperatures, maximum temperatures, rainfall, snow cover, wind, and elevation. In Canada, there are 10 zones, which are numbered from 0 to 9. The higher the zone number, the warmer the climate. Haliburton County is generally considered to be zone 4.
There may also be areas of exception or ‘micro climates’. Factors that contribute to microclimates may be nearby bodies of water, presence of concrete or stone, slopes, soil type, vegetation, or structures. For example, plantings close to a house that are sheltered from northern winds will do well so you might experiment with a plant rated for a warmer zone, like a zone 5. Read the plant tags when you are buying new plants to ensure they will survive year after year.
Beware of imported plants that have the US hardiness zone information on the tags. This is not equivalent to Canadian hardiness zones. As a general rule of thumb gardeners can simply add one zone to the designated USDA zone. For example, USDA zone 4 is roughly comparable to zone 5 in Canada. Buying locally and asking questions at your local garden centre will help alleviate this confusion.
If you want to overwinter perennials outdoors in containers, it’s best to sink them into the ground. This will protect your planter and the plants.