Easily grown in average, medium moisture, well-drained soil in full sun to part shade. Full sun is best in cool northern summer climates. Prefers part shade in hot summer climates. Needs regular moisture. Promptly remove spent flower stems to encourage additional bloom. Divide clumps in fall every 3-5 years to maintain vigor and/or control spread. Plants naturalize by rhizomes, and can be somewhat invasive, particularly in moist soils.
Campanula glomerata, commonly known as clustered bellflower, is an upright perennial that is native to Europe and temperate Asia. It forms a dense foliage clump of ovate to lance-shaped, toothed, somewhat hairy, long-stalked, medium green basal leaves (to 5” long). Upward facing, bell-shaped, violet to lavender blue flowers bloom in spherical terminal clusters atop smaller-leaved stems rising above the basal clump to 12-18” tall. Smaller flower clusters simultaneously bloom in the upper leaf axils. Stem leaves (to 3 1/2” long) are narrower and shorter than the basal leaves. Flowers bloom in late spring to early summer (perhaps into mid-summer if the spent flower stems are promptly removed after bloom).
Genus name comes from the Latin word campana meaning bell in reference to the bell-shaped flowers.
Specific epithet comes from the Latin word glomeratus meaning clustered in reference to the densely packed inflorescences.
Common name is also in reference to the densely packed inflorescences, each having a cluster of up to 15 flowers.
Var. alba grows 1.5-2' tall and has white flowers. This variety is basically a white-flowered version of the popular purple-flowered Campanula glomerata 'Superba'.
No serious insect or disease problems. Snails and slugs are occasional visitors.
Group or mass. Rock gardens, borders, cottage gardens or informal naturalized areas.