How To Prune A Butterfly Bush

When I planted this Butterfly bush, I planted two of them.  Two years later, I trimmed the one in the fall, because it had taken over the space and blocked the back walkway.  The next year, that bush did not come back.  :-(  So for the next 5 years, I did not trim the remaining bush at all.  In the before photo it is about 12 feet tall and at least 8 feet wide.  We could no longer use the steps leading up to the deck, they are completely blocked.  (we could access the deck from the other side)  My husband had enough, he insisted it be pruned.

This is late October.  I've had lots of locals (central PA) tell me this is fine, but I've read that it should have been done late winter/early spring, so I['m concerned this won't live.  In the late winter/spring, you can cut a butterfly bush back to 1 foot - so hopefully, since we left a very good sized bush here, it will be fine.  

"As with knowing how to prune a butterfly bush, when to prune a butterfly bush is another aspect of pruning for which there are no absolutes. In fact, butterfly bush pruning can take place just about any time of the year. However, certain pruning techniques will help promote more vigorous growth and healthier blooms. Generally, most butterfly bush pruning should take place during the winter months, in warmer climates, while the plant is dormant. However, the butterfly bush can also be pruned in the spring with no ill effects. Just make sure you wait until the threat of frost has passed."

I planted these specifically to attract the Hummingbird Moth.  I saw them on a bush at a state park, and was fascinated.  Our bush is loaded with these each year, they do love the flowers.