How to Prune clustered bellflower?
Cut back after flowering to prevent self-seeding and to encourage a second flush of flowers

clustered bellflower · Campanula glomerata
Grow in fertile neutral to alkaline, moist but well-drained soil in sun or part shade. Delicate flower colours are best preserved in shade. Suitable for naturalizing in woodland and wildflower gardens
Cut back after flowering to prevent self-seeding and to encourage a second flush of flowers