Answer: Butterfly bushes can be cut down to ground level each year and it will take all summer for them to grow to their full height and width. During this time you can selectively prune them back, but since they flower on the ends of their branches you will probably cut off some of the potential blooms. If you can't move the plants to an area where they can freely grow, you might want to consider replacing them with some dwarf varieties. For instance, Petite Plum has purple/red flowers; Purple Emporer has purple flowers. Dwarf butterfly bushes rarely grow taller than 3-4' but the flowers are full size. Hope this information helps!
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