Attack Of The Coral Bells

My window flower boxes featured many types of blooms this year.  Remnants of coral bells, grasses and mums existed from last year and so I filled in space with deep jeweled toned petunias, begonias and lobelias.  I was not expecting that the once puny display of coral bell leaves would bloom into such a monster!  They have miraculously taken over the boxes and shoots have started to come out with little lily like buds. 

If they are looking this good now, what does autumn hold in store for these autumnal plants?