Cold Hardiness Zone map is relative to moisture, wind, and temperatures fluctuations and is used as general rule of thumb by gardeners. It can be easier to understand than the new heat zone maps, so many of us use the cold hardiness zone map and pay careful attention to how different areas of our yards are effected by the elements. Protection is the key to understanding the hardiness of plants.

Exposure to the rain, wind and sun can reduce the hardiness of a plant by a full zone. Winter winds and cold/warm fluctuations endanger plants more than prolonged cold temperatures so a wise gardener will take note of these areas and use plants a zone colder and protect soil and plants with mulch.

In a protected area next to a foundation on a south side, then perhaps you can use plants a zone warmer than you normally would. In any yard it is possible to have areas that would be in three different zones. This can provide the opportunity to possible triple the amount of plants used in your landscape gardening plans.