The bottlebrush genus (Callistemon spp.) consists of 34 species of shrubs in the myrtle family (Myrtaceae), the majority of which are native to Australia. The genus gains its common name from the cylindrical, brush-like flowers of the plants. Numerous bottlebrush cultivars are widely grown in warm, moderately dry climates. Crimson bottlebrush (Callistemon citrinus) and weeping bottlebrush (Callistemon viminalis) are among the most popular species.
Crimson bottlebrush is the most widely cultivated bottlebrush species, enjoyed for its narrow, lance-shaped leaves and bright red fuzzy flowers. The plant may be grown as a small tree or a large shrub, growing to be up to 12 feet tall with a spread of about 9 feet. The plant has a distinct citrus-like aroma. Crimson bottlebrush is suitable for USDA zones 8B to 10, where it grows best in a full-sun location with well-draining soil.
Weeping bottlebrush (Callistemon viminalis) is a widely cultivated bottlebrush species characterised by weeping, pendulous branches and dark red bottlebrush flowers. The shrub is slightly less cold hardy than crimson bottlebrush, growing in USDA zones nine to 11. Weeping bottlebrush is tolerant of wet and dry soils. Weeping bottlebrush may reach heights of up to 20 feet, producing a rounded habit. A native of New South Whales, weeping bottlebrush is a common sight in southern California and southern Florida.
Yellow-flowered bottlebrush species include the Kingaroy bottlebrush (Callistemon formosus), a frost-tender weeping variety commonly grown as a street tree in Kingaroy, Queensland, and lemon bottlebrush (Callistemon pallidus), a hardy, frost-tolerant species that flowers in summer. Alpine bottlebrush (Callistemon pityoides) also boasts lemon-coloured flowers. The low-growing variety flowers in spring and summer and is tolerant of frosts and heavy pruning. Prickly bottlebrush (Callistemon brachyandrus) produces red flowers that are covered in a dense yellow pollen. The plant has prickly leaves and prefers hot, arid regions.
Numerous bottlebrush cultivars are available in the nursery trade. Most bottlebrush cultivars are hybrids of either the crimson bottlebrush or the weeping bottlebrush. Popular cultivars include Harkness, Hannah Ray and Dawson River Weeper, all of which are on the large side and have a weeping habit. Dwarf cultivars include Little John, a densely flowered variety that offers blue-tinged foliage. Pink-flowered varieties include Reeves Pink and Mauve Mist, both of which prefer a warmer climate.