Family: Campanulaceae
Common Name: Rock Bell

There are around 150 species in this genus, most of which originate in the southern hemi­sphere. Most are perennials with pretty blue, white or red, campanula-type flowers in summer, and soft, delicate foliage. Wahlen­bergias make lovely pot and rockery plants and also look attractive in massed displays.

Species

W. albomarginata, zone 7, is a tufted, rhizomatous perennial from colder areas of New Zealand. Its flowers are large and pale blue, or occasionally white.

W. gloriosa, Australian or royal bluebell, zone 9, is one of the most beautiful native Australian plants. It is a mat­ting or tufting alpine type, with spreading, underground stems and very large, blueish purple flowers, to 2.5 cm (1 in) across. This species is the floral emblem of the Australian Capital Territory.

W gracilis, zone 10, is an annual species from New Zealand, to 30 cm (12 in), with variably toothed leaves and large flowers, mostly white, sometimes blue or purple.

W. stricta, zone 9, is quite widely grown. It is a variable species with small, soft blue, occasionally white, flowers. Forming clumps, 30-40 cm (12-16 in) high, it occurs widely in Australia.

Cultivation

Outdoors, grow these plants in a sandy, well-drained soil which contains plenty of humus. Choose a spot sheltered from wind and with partial shade. Plants can also be grown in an alpine house if the climate is unsuitable. Plant them in pans of well-drained, sandy, soil-based compost, with added leaf mould. Propagate in spring, either from seed germinated at 15°C (59°F), or by division.

Climate

There are species suited to various climatic zones.