Answer: The USDA winter hardiness zones indicate average winter low temperatures. To be conservative, you would consider yourself to be in zone 6 and could thus select perennials hardy to zone 6 or a lower number. For example, a plant listed as "hardy in zones 3 to 8" would be acceptable, as would a plant rated "to zone 5" or "to zone 6". For annuals, the hardiness zone is relatively meaningless because they live only for one season.
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