Campanula glomerata Seeds | Clustered Bellflower
LATIN NAME: Campanula glomerata
COMMON NAME: Clustered Bellflower
Plant Profile
Clustered bellflower is a robust perennial of meadows, scrub and open woods across Europe and temperate Asia, with dense heads of violet-blue bells at the top of each stem. It grows thirty to sixty centimetres tall, with rough, hairy, toothed leaves and a dense, almost ball-like cluster of upward-facing violet-blue bells at the top of each stem, with smaller clusters in the leaf axils below.
It spreads by rhizomes into substantial clumps and flowers in early to midsummer. The flowers are a strong, clear blue that stands out in grass, and the plant is a favourite of bumblebees, which work the crowded heads from the outside in.
The stems are upright and rarely need staking, even in exposed gardens.
Science & Biotechnology
The tightly packed flower head has drawn attention from pollination biologists, who have compared how bumblebees work a dense cluster against the looser sprays of other bellflowers; the cluster concentrates the reward and cuts the flight time between flowers.
The species is also used in studies of grassland management, since it responds well to late cutting and declines under heavy grazing. Taxonomic work within Campanula has looked at how the clustered species relate to the loose-flowered ones, and at how readily they hybridise where their ranges overlap.
Its nectar is accessible to short-tongued bees as well as bumblebees.
Uses & Benefits
It is a reliable border perennial for sun or light shade, flowering over several weeks and standing up to wind better than the tall, thin-stemmed bellflowers. It also works in a wildflower meadow, where the blue heads show well among grasses, and it is a good cut flower for a jug.
The young leaves are edible in salads, though bitter, and the roots of some related species were eaten in hard times. In the garden its main value is the strong blue colour at a time when most perennials are still in bud, and the fact that it needs almost no staking.
In a mixed border it pairs well with grey foliage and with yellow daisies, which set off the blue.
Growing from Seed
Sow on the surface of a moist, free-draining mix, since light aids germination, and keep at 18-20C. Germination takes two to four weeks. Prick out when the seedlings are large enough to handle and grow them on in a cool frame.
Plant out in spring or autumn in sun or part shade; the plant tolerates most soils but flowers best in a reasonably fertile, well-drained spot. Divide clumps every three years to keep them vigorous, and cut the stems back after the first flush if you want a second, smaller flowering.
Water young plants in dry spells during their first summer.
Old flower stems can be cut to the base once the seed has dropped.
Our Take
Clustered bellflower is one of the most dependable blue perennials for a sunny border, and it asks for nothing beyond division every few years. It is a plant that earns its space without fuss.
Related Reading
Gardeners who grow Clustered Bellflower often pair it with these related subjects: