Answer: Butterfly bushes or Buddleia bloom from mid summer to frost. The plants are normally pruned in late spring, and the amount to take off will depend on a number of factors.
First off, there may be some die back or winter kill after the
winter season and that should be removed. In some years
this could mean cutting it nearly to the ground. In other
milder years this might be just a few branch tips. Next, you
can prune for shapeliness and to encourage bushiness or
branching; you can also prune to try to limit its overall size.
The plant has a naturally gangly shape and can grow very
large in one season, so some gardeners will opt to prune
more than others. Finally, each cut will force the plant to
branch and each branch tip will bloom, so you can also
influence the number of blooms.
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