Answer: Butterfly Bush, also known as Buddleia davidii, blooms on new growth. Therefore, stems should be pruned back in early spring to encourage large, lush flower spikes. You can let it grow into a shrub form, which could eventually be about 12'x15'. I always prune back my Butterfly Bush on St. Patrick's Day to about 6-10" . In your cold winter climate you'll need to mound organic matter over the crown of the plant in the fall to keep the roots from freezing. If you did not protect it over the winter months, you may have lost it. Wish I had better news for you!
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