I've re-read your question and I would say wait till the fall. The
plant is quite busy right now trying to produce flowers and the shock
is too risky in my opinion.

It doesn't look terribly crowded in the picture, although I like a
"full" looking flower bed as opposed to the specimen plant look. A full
bed will also cut down on the sun that gets to your weeds and therefore
cut down on that awful chore.