How to grow Campanula (kam-pan-u-la)
From the Latin campanula, a little bell, hence the common name, Bellflower (Campanulaceae). A large genus of annuals, biennials and perennials for growing in the border, wild garden, rock garden and greenhouse; widely distributed over the Northern Hemisphere.
Border species cultivated C. x burghaltii, 2-i feet, large lavender bells, June and July, sandy soil. C. carpatica, 9 inches, edging plant, also rock garden, flowers blue, July and August, plant in the autumn before leaves die down, avoiding dormant season; vars. `Ditton Blue', 6 inches, indigo; 'Harvest Moon', violet-blue; 'Queen of Somerville', 15 inches, pale blue; turbinata, 6 inches, purple-blue; turbinata pallida, 6 inches, china-blue; 'White Star', 1 foot. C. grandis (syn. C. • latiloba), 3 feet, sturdy, rather stiff growth, flowers close-set in spikes, open flat, blue, June and July, creeping root-stock, lift every third year, grows in shade. C. lactiflora, the finest of the bellflowers, 4-5 feet, establishes well in good moist soil, stem erect, covered with foliage, branching to trusses of lavender flowers, July and August; vars. 'Loddon Anna', pale pink; 'Pritchard's Variety', deep blue; 'Pouffe', 1 foot, dwarf variety, light blue. C. latifolia, 2 feet, blue, June to August, easy to grow, tolerates shade; vars. alba, white flowers; 'Brantwood', 4 feet, violet-purple; macrantha, deep violet flowers, this species sometimes attracts blackfly. C. persicifolia, the peach-leaved bellflower, 2-i-3 feet, best species to grow in the shade, sends out stolons and forms rosettes of leaves from which the wiry flowering stem grows, producing lavender flowers in June and July; vars. 'Fleur de Neige', 2 feet, semi-double white; 'Snowdrift', single white; 'Telham Beauty', large, single, lavender-blue; 'Wedgwood Blue'; Wirral Belle', good double deep blue; also mixed 'Giant Hybrids'. C. rotundifolia, 3-4 inches, the English harebell and Scottish bluebell, well-known on chalk and light soils, bears single nodding delicate flowers, July and August; var. olympica, 9 inches, lavender-blue, June to September. C. sarmatica, 1i feet, spikes of pale blue flowers, July, greyish leaves.
Rock garden These are mainly dwarf species which require a gritty, well-drained soil and an open, sunny position, except where noted. All are summer-flowering unless otherwise stated. C. abietina, 6 inches, violet. C. alliariaefolia, 2 feet, white. C. arvatica, 3 inches, deep violet, needs scree conditions; var. alba, white. C. aucheri, 4-6 inches, tufted habit, deep purple, early. C. bellidifolia, 4 inches, purplish blue. C. calaminthifolia, prostrate, grey leaves, soft blue flowers, alpine house. C. carpatica (as border species). C. cochlearifolia (syn. C. pusilla), 3 inches, bright blue; vars. alba, white ; 'Jewel' 4 inches, large, blue ; pallida, pale blue. C. elatines, 6 inches, purple blue. C. formaneckiana, 15 inches, silver-grey leaves, pale blue or white flowers, monocarpic, best in the alpine house. C. garganica, 4 inches, blue, good wall plant; vars. hirsuta, light blue, hairy leaves, May onwards; 'W. H. Paine', dark blue, white centres. C. hallii, 4 inches, white. C. herzegovinensis nana, 1 inch, deep blue. C. jenkinsae, 6 inches, white. C. kemmulariae, 9-12 inches, mauve-blue. C. linifolia, 9 inches, purple. C. nitida (syn. C. planiflora), 9 inches, blue; var. alba, 6 inches, white. C. portenschlagiana (syn. C. muralis) 6 inches, trailing, purple, good wall plant. C. poscharskyana, 6 inches, powder blue, walls or banks; var. lilacina, lilac. C. pulla, 4 inches, violet, likes limy soil. C. raddeana, 1 foot, deep violet. C. raineri, 1 inch, china-blue, scree plant. C. sarmatica, 9 inches, grey-blue leaves and flowers. C. saxifraga, 4 inches, deep purple. C. speciosa, 9 inches, purple blue. C. stansfieldii, 4 inches, violet. C. tridentata, 4-6 inches, deep blue. C. valdensis, 6 inches, grey leaves, violet flowers. C. warleyensis, 3 inches, blue, double.
Rock garden cultivars 'Birch Hybrid' (C. portenschlagiana x C. poscharskyana), 9 inches, purple blue; 'G. F. Wilson', 4 inches, violet-blue; 'Patience Bell', 3-4 inches, rich blue; 'Profusion', 4-5 inches, blue; 'R. B. Loder', semi-double, mid-blue. Wild garden The growth of these is too rampant for the border. C. barbata, 1 foot, clear pale blue flowers. C. glomerata, native plant, 1 feet, head of closely-packed deep purple flowers, June to August; vars. acaulis, 6 inches, violet-blue flowers; dahurica, 1 foot, violet; superba, 1 foot, purple. C. rapunculoides, 5 feet, drooping flowers, deep blue, spreads rapidly. C. thyrsoides, 1 foot, yellow bells in closely-packed spike, summer, monocarpic. C. trachelium, 2 feet, purple-blue flowers on erect stems June and July.
Greenhouse C. pyramidalis, the chimney bellflower, a biennial, 4-5 feet, spectacular, covered with white or lavender flowers. C. isophylla, a trailing plant for hanging baskets or edge of greenhouse staging, lilac-blue flowers, summer; vars. alba, white flowers, mayi, woolly variegated leaves.
Biennial C. medium, Canterbury bell, 2i feet, in shades of pink and blue, and also white forms; vars. calycanthema, the cup-and-saucer type; fore pleno, double, 3 feet, with white, blue or pink flowers. Cultivars include 'Dean's Hybrids' with single or double flowers.
Annual C. ramosissima, 6-12 inches, pale blue to violet, this is not often grown but may be used to fill gaps in borders. Sow seed in early April and thin seedlings to 4-6 inches apart.
Cultivation: Border Many of the border campanulas may be grown in partial shade; most like a well-cultivated soil. Plant in spring or autumn. Stake tall species. They are propagated by seed sown in pans in very fine compost, with no covering of soil, put in a shaded frame. Prick out seedlings and harden them off before planting out. Propagate plants with creeping roots by division in autumn.
Rock garden Propagate these kinds by seed sown in March in frames, by division in spring, or by cuttings after flowering. Wild garden Plant out kinds suitable for the wild garden in spring or autumn, in sun or partial shade. Propagate them by seed or division as for border kinds.
Biennial Seed of C. pyramidalis is sown in pans in a cold frame in May and the seedlings potted up singly. Pot on until they are finally in 8-inch pots. Grow them in cool conditions, giving them ample ventilation. Plants may also be used out-of-doors in the border. Canterbury bells (C. medium) are raised in a shady site from seed sown in May or June. The bed should have a very fine tilth, and seed drills should be shallow; or sow in boxes in finely sieved soil and put the boxes in a frame, transplant seedlings to a nursery bed 6 inches apart. Set out in autumn where the plants are to flower. having added lime to the soil. C. isophylla and its varieties are propagated by cuttings taken in early summer and rooted in a greenhouse propagating frame. Potting compost is a suitable growing medium; the plant does best in a cold greenhouse or conservatory as it is nearly hardy and, indeed, may survive out of doors in sheltered gardens. It may be used for planting up hanging baskets intended for outdoor decoration in summer.