I had good intentions of using this plant in my post yesterday, in honor or William and Kate's wedding, but I guess in my excitement of having my DSL back working I totally forgot.
I'm kind of new to Campanulas and it is a love hate sort of relationship. This one especially. It is gorgeous. The flowers are large, but still delicate and the purest white. They are borne in profusion and last for a long time. But . . . they seed voraciously. If you're not careful, you will have a forest of the things in no time at all. So, plant them by all means, but deadhead most of them, leaving maybe one or two blossoms to make you some new plants for next year. They don't seem to spread far - just drop their seeds at the base of the plant, so it is easy to just pluck them out if you get too many.
The flowers are double, two perfect flowers, one inside the other. They are hardy to zone 5. Expect them to get about 18" tall. They like sun, average soil that is neither too dry nor to wet. And so far, deer don't seem to eat them which is a plus for any plant in my garden. For those of you who like to pick flowers to bring into the house to enjoy, these make excellent cut flowers.
They seem to be readily available at a number of mail order nurseries and you may find them in garden centers also.
We had the first totally wonderful sunny day that we've had in a long time today and we totally enjoyed it - though I'm really tired now. Lots of new things dug and potted for the nursery and lots of just walking and enjoying the plants.