Lancashire,
United Kingdom 
Campanula persicifolia - lovely plant. I have planted it several times. It doesn't die but what happens every time is the plant merely produces basal growth the next year with no flower stem. What is more the ones that grow from seed do the same. They come up every year and look very healthy but only produce basal growth. It happened on clay soil in my old garden and now on the sandy soil where I live now. Any ideas please ?
31 Jul, 2013
Answers
Oops. Slight oversight. Fixed now: Campanula persicifolia.
1 Aug, 2013
Freely confess I have no idea it is a hardy perennial and should flower year on year.
1 Aug, 2013
Please tell me how you manage to stop it flowering and seeding itself all over the garden? I have just dug out 5 wheelbarrow loads of it, just from one border.
1 Aug, 2013
Exactly...
1 Aug, 2013
The seeds from the occasional one I purchase produce new plants but these merely grow into healthy basal growth that shows not the slightest interest in producing flowers. The original plant itself also reverts to just basal growth. It is weird. That is how it doesn't spread all over the garden - it never grows new flowers.
1 Aug, 2013
Lucky, lucky you!
2 Aug, 2013
(Sigh) . . . Looks like I have achieved something nobody else ever has ! <laughs>
2 Aug, 2013
Well if you want to try some you are welcome to come and dig out as much as you want, both blue and white.
2 Aug, 2013
The name of the plant would be a real help Cosmo...
31 Jul, 2013