Answer: Since the plant is sprouting, it is coming back. A hard pruning into live wood such as that can shock the plant, but it should come back from the ground. Pruning butterfly bushes is a bit of an art. You need to remove all dead wood each spring, and some years this can mean cutting it to the ground and waiting for it to resprout from the roots. Other years, there may be quite a bit of live growth left and then you will trim it partly to shape it and partly to encourage bushiness. Trimming back to about 12 or 18 inches would usually be sufficient, and you can trim it back even less if desired.
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