Plant hardiness zones help us to establish what we can grow and where. Zones are numbered from 0 (the coldest zone) to 9 (the warmest zone). Please use plant hardiness zone maps with caution. They are a good starting point but it is important to consider other factors when selecting plants. You may technically live in zone 4b but may have a little heat sink (microclimate) somewhere on your property that would bump you up to a zone 5A. Your own soil conditions, microclimate and topography will be equally important in determining the correct varieties for you. See (http://www.planthardiness.gc.ca/) for a selection of zone maps and additional information.