Answer: Unfortunately, butterfly bush is not reliably hardy in zone 5, and according to your zip code you are gardening in zone 5A or the coldest part of zone 5. Depending on your microclimate it might actually be as cold as zone 4. So I doubt that it is still alive, especially if it is in a container where the roots are not as well insulated -- both from cold and also from the freeze/thaw cycles that happen when temperatures oscillate -- so that is especially stressful on plants. Usually one would trim it back to live wood when the buds begin to swell in the spring. If you are not seeing any signs of life, not even down on the lower parts of the plant near the soil line, then it is probably gone. I'm sorry I can't be more encouraging.
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