The first thing you have to know before you begin to purchase any plant material for your garden is what hardiness zone you live in. The new hardiness map of Canada is divided into nine major zones. The harshest (coldest region) is 0 and the mildest (warmest region) is 8. Subzones (e.g., 4a or 4b, 5a or 5b) are also noted in the map legend. http://sis.agr.gc.ca/cansis/nsdb/climate/hardiness/intro.html
For example, Montreal and the surrounding areas fall into Zone 5 and Subzone 5b. Montrealers can purchase plant material which can survive in zones 0-5 but not higher. In a nutshell, the rule of thumb is plant material falling into a lesser zone (less than 5) will survive but chances are plants in the higher zones (6-8) will not. (There are always exceptions to the rule)
Hardiness zones are indicated for each plant on the little identification tickets in the nurseries. Then again…Google it if you aren’t sure!