We planted a butterfly bush two summers ago. At the end of the first season I didn't know if I should cut it back or just leave it alone and after a little research decided to cut it back. Last year it took forever to come back and I thought I had done it in. Last fall I just trimmed it back to about three feet and it started leafing a lot sooner this year. What do you do with yours? Do you dead head it like other pereniels or just leave the spent flowers hanging?