Answer: Unfortunately, in a cold winter climate such as yours it is very difficult to overwinter plants outdoors in a container. The reason is that the roots are not as well insulated as they would be in the ground. The extreme cold can damage the roots, as can the freeze/thaw caused by oscillating temperatures in spring or fall. You might be able to grow something like a dwarf Alberta spruce for a year or so, however that is a fairly basic evergreen so I am not sure that means your design goal. I'm sorry I can't be more encouraging.
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