Question
Hi Tom:  We have discovered that, along with our butterfly bush, which was purchased and planted in the fall of 2005, we have another plant that has similar leaves but much different flower buds growing within the the buddleia davidii.  The 'trunk' of the companion plant is much thicker and taller with leaves that are a bit wider and more serrated.  The blossoms on the companion are clustered like a queen anne's lace might look.  When we've identified this other plant, when and how can we separate them?

Answer
Hi Pat,
Thanx for your question.  Sometimes butterfly bushes are grafted on to hardier Buddleia species.  My guess is that is what you are seeing is the hardier version coming up.  If this is the case, you can't separate the plants.  If you did the root ball up you should be able to see where the graft was made.  If there truly are two separate plants you should dig them up in the early fall at least 30 days before the first frost and separate them replanting immediately.  If the plant is in fact grafted if you allow the donor plant to grow it will smother out the original graft.  I hope this helps.
Tom