This member of the aster family is a short lived perennial and you can cut it back by two thirds as soon as it finishes the first flush of blooms or cut it back by half in late spring to encourage shorter and more bushy growth. There are several varieties so perhaps you have a taller version. This plant also thrives in dry, rocky soil so if you have been watering and feeding then the growth habit will be much more lush and tall. One more thing - the common name is Cupid's Dart as the ancient Greeks thought that these blooms would make someone fall in love. Enjoy your ambitious bloomer and keep growing, Marianne Binetti