I am very happy with the growth of my Dahlia campanulata this year. I was a gift from the great Ed Bowen two years ago. Last year it did take a while to get up and running this year he is looking great already, at least three-foot tall. I got a few flowers out of it last year but I did had to move it under glass in the autumn, this year if I can get it big in Mrs Next-doors summer-house and then get it out maybe we will have better flowering. For all of you in the USA, Ed Bowen has a great nursery Opus Plants, if you are looking for something interesting he is your man, one of the greats of American Horticulture.