I have not had much success with fountain butterfly bush -- I've managed to kill two. I have no problem with buddleia davidii -- in fact they self-sow in my garden. I live in zone 7 - Northern VA. I'm thinking of trying one more time -- is there any thing special I should know? The site is partly sunny and well-drained.
Thanks --
My neighbor has had one for years, and she does absolutely nothing to it. It's in full sun, gets watered once in awhile, and gets pruned once a year. I've never seen her add anything to improve the soil - it just flourishes. We're in zone 10, Southern California. Wish I could offer better advice - good luck.