The species of the genus Campanula include annual, biennial and perennial plants. They vary in habit from dwarf, medium to tall plants distributed in a temperate zone. I grow several species of bell flowers: low and creeping Campanula poscharskyana in the rock garden, tall and robust Campanula medium, Campanula glomerata, Campanula lactiflora'Loddon Anna' and Campanula persicifolia 'Alba'. They are all perennials with an exception of C. medium, which is biennial.
Campanulas look good in mixed borders and catch the eye, especially Canterbury Bells. It is a biennial plant which means it grows leaves in the first season and flower in the next. I usually collect the seeds and sow them immediately. They are self sown too but I love to have good developed plants to transplant in the spring next year.
Campanula medium, double flowers
They need rich, well drained but moist soil in sun or light shade. I just love the expectation and excitement of not knowing what kind of flower will turn out of seeds. They are usually white, pink, blue and mauve in colour. Sometimes double flowers appear. They look good either planted in mass or mixed with other flowers. They are classic cottage garden flowers.
Perennial bell flowers are really easy to grow and they spread easily. The flowers are mostly blue and white. Campanula glomerata is very nice when blooming. The flowers are clustered on the end of stems. It spreads well and needs to be divided and replanted every 3 or 4 years or when it outgrows it's place. It flowers only two weeks and looks a bit untidy after flowering, so I always cut them back when the flowers fade away.