Answer: Buddleia davidii, the butterfly bush, can be transplanted now or in the fall. I would do it now if it were mine, since it blooms in July right up until frost. I HATE to move something that is blooming. When the plant is giving its all to making flowers and seeds it seems a shame to shock it additionally by moving it. You may cut back somewhat on this years bloom, but by next year it should be just fine. It isn't necessary to use a root enhancer, just provide plenty of water during the growing season and they'll become established in no time at all.
Remember they like good soil where they will receive plenty of sun. Mulch them generously come fall to offer a bit extra protection over the winter.
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