With their beautiful white flowers or flowers coloured in all imaginable shades of blue and violet, bellflowers (Campanula) are invaluable for summer gardens. The genus belonging to the Campanulaceae family comprises over 300 species. Most of them are deciduous perennials, but some are also evergreen. Few species are cultivated one year or two years. They occur naturally in the most diverse habitats on the northern hemisphere. Many come from the Mediterranean region, the Balkan peninsula and the Caucasus, a few from East Asia, North America, Iran and the Himalayas.
As diverse as the location requirements of the various species are, as diverse is their occurrence in nature. Because bellflowers grow in meadows and mountain mats or in high mountains. The right type can also be found in the garden for almost every location: from the living area of the bed to the edge of the grove, open space to rock steppe, stone plants, stone joints and wall crowns – the spectrum is wide.
Appearance and growth
Also with regard to the size and its growth-behavior, the different types of the bellflower clearly differ. While the smallest species such as the dwarf bellflower (Campanula cochleariifolia) or the Carpathian bellflower (Campanula carpatica) grow compactly, form low cushions and can sometimes grow only ten centimetres high, large species such as the cone bellflower (Campanula lactiflora) reach heights of up to two metres and have elegant, upright growth.Bellflowers are easily recognisable by their bell-shaped, tubular or star-shaped flowers, which open between June and September, depending on the species and variety. The bellflowers also owe their name to them, because Campanula means “little bell” translated from Latin. The majority of all bellflowers bloom in violet or blue. The colour spectrum ranges from pale sky blue to deep violet. But there are also numerous white flowering varieties, for example the dwarf bellflower ‘Bavaria White’ or the ball bellflower ‘Alba’. But not only the colour and shape of the flowers are variable. The arrangement of the individual flowers also varies from species to species. Sometimes they stand in panicles, sometimes in grapes, often however also individually. The leaves are undivided, but may be heart-shaped or toothed.
Location and soil
Most bellflowers have one thing in common: they prefer a sunny to semi-shade location, thrive in any nutritious, permeable soil and react somewhat sensitively to moisture.
The low, cushion-forming species prefer a permeable soil. In order to create an optimal location, the soil can be sanded before planting. Otherwise, bellflowers can be planted from spring to autumn.
After flowering or – in the case of species that are to become wild by sowing themselves – in spring, bellflowers are cut off about a hand’s width above the ground. Most species and varieties are divided in spring or autumn. This should be done about every 6 to 10 years, when the plants begin to balm. The two species used as indoor plants grow very quickly and therefore need regular water and fertilizer. The soil in the pot should always be moist. Fertilizer is applied once a week between April and August.
Wintering or winter protection
Species that are used as houseplants can go out on the balcony in summer, but should move back into the house at the beginning of September. Here they are first cut and then in the winter months only little watered and not fertilized. The temperatures in the winter quarters should not exceed ten degrees Celsius.
Bellflowers can be used in many ways in the garden according to their location requirements. The low, cushion- and mat-forming species bring colour to stone joints, masonry crowns and rock gardens. For example, they go well with low yarrow (Achillea), thyme (Thymus) or gypsophila. In sunny, mixed herbaceous borders, higher species such as the peach-leaved or the tangle-bellflower make a good figure next to higher yarrow, evening primrose (Oenothera), summer margerite (Leucanthemum) or candelabra prize (Veronicastrum). Because of their romantic flower shape they are also popular rose companions. For shady beds, the most suitable partners are the Astilbe, the Digitalis or the Aruncus. Some species of the bellflower are even used as houseplants. Two Italian species are particularly popular here, but they are somewhat sensitive to frost: the Fragile Bellflower (Campanula fragilis) and the Star Bellflower (Campanula isophylla). Both form their flowers on longer shoots that hang beautifully over the rim of the pot. They will be offered from March onwards. In summer, however, these species can also be planted in balcony boxes, provided they are wintered indoors. The hardy Dalmatian bellflower is also often offered as an indoor or balcony plant.
Important species and varieties
The large genus of bellflowers is often divided into several groups according to its possible uses in the garden. The first group includes medium-sized to large species suitable for planting wild herbaceous plants and flower beds, such as the ball of bellflower (Campanula glomerata), the broad-leaved forest bellflower (Campanula latifolia), the marian bellflower (Campanula medium) or the peach-leaved bellflower (Campanula persicifolia). There are numerous varieties of the latter in particular on the market, some of which may have single flowers and some of which may have double flowers. Many of the high species are also well suited as cut flowers.
Bellflowers in the our store-Shop
The second group includes low-growing species that prefer dry, lean sites and are therefore well suited for rock gardens, dry-stone walls and troughs. These include, for example, the dwarf bellflower, the Carpathian bellflower, the Dalmatian bellflower (Campanula portenschlagiana) and the hanging cushion bellflower (Campanula poscharskyana). For lovers, however, this genus has numerous other species available that do not fit into either of the other two groups, for example the biennial ostrich bellflower (Campanula thyrsoides) or the numerous varieties of dotted bellflower (Campanula Punctata hybrids) such as ‘Beetroot’ or ‘Sarastro’.
The Broad-leaved Forest Bellflower (Campanula latifolia var. macrantha, left) and its white flowering variety ‘Alba’ (right)
The reproduction possibilities of bellflowers are as varied as the genus itself. Some can be propagated by rooted leaf rosettes, others by basal cuttings. However, most species are divided or can be grown from seeds. In addition, some species reproduce by self-seeding.
Diseases and pests
Only occasionally are bellflowers attacked by grey mould or downy mildew. However, bellflowers are most endangered by rust. This fungal disease occurs in bellflowers in three forms. While Coleosporium tussilaginis occurs mainly on the ball bellflower and the peach-leaved bellflower, the latter can also be attacked by the specific campanula rust (Puccinia campanulae). The rust fungus Aecidium campanulastri also frequently occurs on bellflowers. The Carpathian bellflower, in particular, often suffers from snail-eating.
I am Don Burke, one of the authors at My Garden Guide. I am a horticulturist that cultivates, grows, and cares for plants, ranging from shrubs and fruits to flowers. I do it in my own garden and in my nursery. I show you how to take care of your garden and how to perform garden landscaping in an easy way, step by step.I am originally from Sydney and I wrote in local magazines. Later on, I have decided, more than two decades ago, to create my own blog. My area of specialization is related to orchid care, succulent care, and the study of the substrate and the soil. Therefore, you will see many articles dedicated to these disciplines. I also provide advice about how to improve the landscape design of your garden.