Answer: Unfortunately it is very difficult to overwinter shrubs in containers outside, especially evergreens, so you may be disappointed. The reason is that the roots are not as well insulated as they would be in the ground; the exposure to cold is stressful and so is the exposure to oscillating temperatures in the spring and fall, they tend to dry out and discolor or defoliate or die back. You might experiment with overwintering the container plant in a dark and cool but just above freezing location such as a garage, bring it inside in late fall, keep the soil just barely damp (not bone dry) and take it back outside in the spring to wake up naturally with the season. Some people have success with dwarf Alberta spruce or yews, however many end up being replaced each spring. I'm sorry I can't be more encouraging.
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