Campanula, also known as bellflower, is a huge genera with over 300 species. The tall perennial species, such as C. persicifolia and C. lactiflora, are usually grown in herbaceous and mixed borders. Alpine campanula are the lower growing species that do well at the front of the border, such as C. carpatica.
These dwarf compact varieties are sometimes called alpine bellflowers. They produce masses of blue, purple or white bell-shaped flowers between mid summer and autumn. They are tough little plants that don’t need much looking after. Most of them can be grown on rock gardens, in wall crevices and in troughs. Their preferred conditions are a sunny or part-shaded position in neutral to limy well-drained soil.
Not only are Alpine Campanula hardy, drought-tolerant and attractive to pollinators, they also have a long flowering season, from mid summer to autumn. They are also tolerant of full sun through to part shade, so are useful for rockeries, paving stones, border edges, gravel gardens, patio containers and woodland areas.
In ideal conditions some species can become a bit too rampant. For example, C. cochleariifolia, C. poscharskyana and C. portenschlagiana are vigorous species and will quickly colonise an area. However, their spreading nature makes them good for suppressing weeds. But there are many highly attractive and better-behaved forms available. These include C. cochlearifolia ‘Elizabeth Oliver’, C. poscharskyana ‘Blauranke’ and C. portenschlagiana ‘Catharina’.
Some alpine campanula are a bit more of more of a challenge. Some are lime haters and won’t survive in alkaline soil. These need a non-alkaline growing medium and do best on a scree bed in crevices or grown in pots in an alpine house. Other groups that need the cover of an alpine house include frost-tender types and the delicate species grown on tufa, C. morettiana and C. oreadum. Protect the hairy-leaved types, such as C. cashmeriana, from the winter wet.
Many species are biennials or short-lived perennials and some are monocarpic setting seed only once. This means that many of them will self-seed, which is valuable in a rock garden setting. Apart from the special groups mentioned, the cultivation needs of the alpine campanula are straightforward. Simply dig in some grit to the soil, water them in well and you will be rewarded with a long-flowering gem of a plant.
Versatile Alpine Campanulas
Alpine campanulas are useful in many garden situations, including rock and scree gardens. But they also add colour and interest to summer containers, raised beds and at the front of borders. Being versatile alpines, they will flourish in most well-drained situations but would not cope well with clay soil in winter. Alpine campanulas are long-flowering and easy to maintain. For a further flush of flowers through summer, pull off faded stems and snip the foliage to ground level.
Many campanulas do not like to be too congested so are best divided up every year or two in spring or autumn.”
Alpine Campanula Species and Varieties
- C. barbata, the bearded bellflower, is a biennial/perennial type. Plant with other low-growing plants in a border or in a scree bed. Dislikes alkaline soil. Height: 20-30cm.
- C. ‘Birch Hybrid’ AGM (H4) is a long-flowering variety and is not invasive, unlike its parents C. portenschlagiana and C. poscharskyana. Flowers between June and September. Height: 20cm.
- C. carpatha forms a neat cushion of long, sharply-toothed, hairy leaves and masses of bell-shaped violet-blue flowers. Spread: 30cm.
- C. carpatica var. turbinata ‘Jewel’ produces masses of deep-purple cups over a dome of foliage. Height: 30cm. Spread: 50cm.
- C. carpatica ‘Bressingham White’ is a neat, compact, pure-white bellflower. Flowers in July and August. Height: 15cm.
- C. cochlearifolia ‘Elizabeth Oliver’ produces masses of dainty, bell-shaped, pale-lavender flowers between late spring and late summer, above small, rounded foliage. Plant in cracks and crevices or as ground cover. Height 10cm. Spread: 30cm.
- C. garganica ‘Dickson’s Gold’ forms a mound of golden foliage, topped by mid-blue starry flowers from June to August. Best in part shade. Height: 5cm. Spread: 30cm.
- C. garganica ‘WH Paine’ AGM (H4) is a reliable plant that produces masses of white-centred, blue, star-shaped flowers in summer.
- C. incurva is a biennial or short-lived perennial with rosettes of grey-green, hairy leaves, from which arise spikes of large, pale-blue bellflowers. The plant can spread up to 1m across in the right conditions. Height: 30cm.
- C. morettiana is a saxatile (rock-dwelling) species with midnight blue-violet flowers. Grow on tufa and keep in an alpine house. Provide good ventilation and mist to prevent red spider mite. Height: 15cm. Spread: up to 40cm.
- C. portenschlagiana AGM (H4) is another dwarf bellflower that spreads easily. It is useful for suppressing perennial weeds. The plant forms a low mat of dark-green, toothed, rounded leaves and produces violet-blue, bell-shaped flowers in summer. A well-behaved form is ‘Catharina’. Height: 15cm. Spread: 50cm.
- C. poscharskyana is a semi-evergreen, trailing, vigorous species that spreads, perhaps a bit too well. A well-behaved form is the droughttolerant ‘Blauranke’, which is one of the best low-growing, long-flowering campanulas. Height 20cm. Spread: 1m.
- C. poscharskyana ‘Pinkins’ PBR is a clear pink form of this vigorous species. It is well-behaved and flowers from June to September. It produces deep-pink star-shaped flowers with a white eye and trailing stems. Does best in full sun but will also thrive in partial shade. Can be grown in pots, on scree or the rock garden. Height: 15cm.
- C. rotundifolia is our native hardy harebell, a biennial that naturalises in grass and in borders.