Plants for Zone 3

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Zone 3a and Zone 3b Plants Many of the perennial plants in our catalog are well-suited for Zones 3a or 3b. Some of our favorite species of athyrium, baptisia, brunnera, cypripedium, dianthus, hemerocallis, hosta, iris, phlox, pulmonaria, and tiarella can survive Zone 3 winter temperatures. Be sure to read how we assign hardiness zones to our plants. The USDA Plant Hardiness Zone Map is based on the average annual minimum winter temperature, divided into 10-degree F zones. Each zone is then subdivided into 5-degree F sub-zones. Zone numbers increase as you move from north to south. Zone 3a annual minimum winter temperatures should be -40 to -35 °F (-40 to -37.2 °C). Zone 3b annual minimum temperatures should be -35 to -30 °F (-37.2 to -34.4 °C). Keep in mind that the zone designation does not tell you how many days the area may reach those average minimums. There can also be a major difference between what plants will grow in the 'a' or 'b' sub-zones.