Campanula myrtifolia – this is the only Campanula I currently grow in the greenhouse and it is significant that it is rather different from other species and indeed has spent time out in the related genus Trachelium. I treat it much as the Trachelium, in particular I cut it back hard after flowering. It still seems to be harder than Trachelium to keep as a tight cushion and I have lost plants from time to time. I propagate by picking off rooted stolons when I repot. Like the others in the genus it suffers the attentions of red spider mite and this can seriously weaken a plant. Apparently now there is no chemical treatment available in the UK against red spider mite to the general public. There are various soap based treatments that might help. However there is biological control and that is something I am intending to try later this season.
Campanulas – for the "alpine enthusiast" over the years there seems to have been a decline in availability of the really small species, mainly from Europe like C. Moriettiana, C. Zoysii, C. Raineri and the US C. Piperi to be replaced by much larger species from Greece and Turkey. Perhaps it was because those smaller plants are hard to place, under glass they draw and are martyrs to red spider mite and rust, in a trough they are basically expensive slug bait.
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Campanula "Bumble Bee" was raised by Joe Elliott and was I believe a chance hybrid. I've seen the parentage quoted as C. Lasiocarpa x C. Piperi but I thought I read somewhere it was C. Raineri x C. Piperi. Whatever, it is a lovely plant and was very popular for a while. Now, it is less often seen.
Campanula raineri – this is the true plant, there are many imposters. Like many campanulas there is also a white form.