Lawn and Garden: Plant Hardiness Zones

Plant hardiness zones indicate which locations have a climate more suitable for growing various trees, shrubs and flowers. In Canada there are 9 major zones. These zones are calculated based on average climatic conditions and altitude of each area. The harshest zone is 0 and the mildest 8. Each major zone is divided into subzones a and b (for example 3a and 3b) where zone a is slightly harsher than zone b