These tender plants are related to gloxinia (Sinningia) and African violet (Saintpaulia) and look something like a cross between the two. They have fleshy, sometimes velvety leaves, and their trumpet-shaped flowers appear over a long season; some kinds flower intermittently all year.
Several species are of interest to fanciers, but the most widely available cape primroses are large-flowered hybrids, which form a 2-ft.-wide clump of long, narrow leaves. Foot-tall stems carry 112- to 2-in. flowers in white, blue, pink, rose, red, purple, often with blotches in a contrasting color. Plants in the subgenus Streptocarpella are similar, but leaves are held in stemless rosettes rather than on erect stems.
All types are typically grown in containers in rich potting mix; repot annually in spring. In frost-free areas, grow outdoors in partial shade. Indoors, grow in bright light but with protection from hot sun. When in growth, water liberally but allow potting mix to dry between soakings. Apply a high-potash fertilizer every other week. In winter, cut back on fertilizer and keep plants barely moist. Remove spent flowers and stems.