Kohleria is a genus of flowering plants in the Gesneriaceace family. They are native to the tropical Americas. Being in the same family as African violets, Kohleria requires similar care. The plants go dormant during the winter, however, unlike African violets. A number of cultivars have been created, and Kohlerias are popular as indoor houseplants.
The primary species grown is Kohleria amabilis, also known as the tree gloxinia. In its native habitat, it can grow to 2 ft (60 cm) tall. The egg-shaped leaves are usually 3.9 to 4.1 in (10 to 10.5 cm) long and slightly less wide. Cultivars grown as houseplants are usually slightly smaller.
The 2-inch (5.1 cm) flowers are nodding. They are tubular, being bright pink on the outside and spotted with red inside. Most cultivars do not grow upright and are suitable for hanging baskets. The cultivar Longwood has bright red flowers with speckled throats, while others are white or yellow. Flowering is generally from late in the winter through the spring and summer.
Kohleria plants prefer bright, indirect light and do well under 14-16 hours of fluorescent lighting per day. It is best if the lights are within 18 in (46 cm) of the plant’s leaves. These tropical herbs prefer fairly warm temperatures of 65-70°F (18.3-21.1°C) at night, and 75°F (23.9°C) or more during the day. They should be planted in soil that has been amended with peat moss and sand. The plants should be fertilized monthly while they are growing.
After flowering, Kohleria requires a rest phase during which it goes partially dormant. Watering should be cut back and fertilizing ceased during this time. The plants should not be allowed to dry out entirely, however. Also, foliage should be trimmed back in this period.
At the time of replanting, after the dormant period, one should repot the rhizome and discard the rest of the plant. Kohleria will survive general household humidity, but like most members of the Gesneriaceae family, prefers more humid conditions. Ideally, it should be grown over a tray with slots or containing pebbles, so that water can build up and provide humidity around the plant.
While many of the species are herbs, Kohleria erianthia is a cultivated shrub that grows to 4 ft (1.2 m) high. It usually blooms in winter and spring. Its orange-red flowers reach 2-inches (5 cm) long, with yellow spots inside. Various cultivars of this species are also available.