The beauty of bottlebrush plants, native to Australia and New Caledonia, comes from their colorful stamen, the male part of the flower, not the petals. The genus name Callistemon means beautiful stamen. Their colorful spikes of flowers are in the shape of brushes used to clean bottles, hence their popular name. They thrive along creek beds, flood zones, or other areas with damp or wet soil.
Thirty species of bottlebrush are native to Australia; four are native to New Caledonia. They are popular ornamental plants. Although they can be grown from seeds, they are most often propagated as cuttings or grown from nursery seedlings. Bottlebrush shrubs and small trees will grow in a variety of soil conditions. They will tolerate drought and being waterlogged, but they should be watered in dry summers. Most species will tolerate light frost; they need to be protected from the wind.
Prickly bottlebrush (Callistemon brachyandrus) has a rounded form and grows to about 10 feet tall. Iit does well in hot, dry areas and in full sun. Its small, red spikes of flowers are covered with yellow pollen. Kingaroy bottlebrush (Callistemon formosus), planted along the streets in Kingaroy, Queensland, has weeping branches and grows to 10 feet tall. It yields spikes of lemon-colored flowers throughout the year. Tonghi bottlebrush (Callistemon subulatus) produces red flowers during the summer and grows from 3 to 10 feet tall. It can be kept compact with light pruning after it flowers.
Cliff bottlebrush (Callistemon comboynensis) produces crimson flowers and grows to 6 feet tall. Scarlet bottlebrush (Callistemon rugulosus), native to Victoria and South Australia, produces red flowers and grows to 13 feet high. Betka bottlebrush (Callistemon kenmorrisonii), another species with red flowers, grows to 10 feet tall in the Betkaa River area of eastern Gippsland. The hybrid dwarf cultivar Callistemon 'Little John' has blue-green foliage and produces masses of flowers.
Crimson bottlebrush (Callistemon citrinus) is widely cultivated and is the best known bottlebrush. It yield spikes of bright red flowers in the summer and autumn and grows to 13 feet tall. The weeping bottlebrush (Callistemon viminalis) grows from 16 to 22 feet tall. Birds are attracted to the nectar in its spikes of bright red flowers. Three hybrid cultivars with spikes that droop or "weep" are Callistemon 'Dawson river,' Callistemon 'Hannah Ray,' and Callistemon 'Harkness.' They all grow from 13 to 16 feet tall.
Willow bottlebrush (Callistemon salignus) has papery white bark and grows from 16 to 40 feet tall. Its flower spikes are usually greenish or white, but some forms produce mauve, pink or red blossoms. It is planted both in gardens and along streets.
Althugh most bottlebrush will tolerate some frost, two species are especially hardy. Lemon bottlebrush (Callistemon pallidus) produces spikes of lemon-colored flower and grows to about 10 feet tall. Cultivars of alpine bottlebrush (Callistemon pityoides) grow as a compact bush about 3 feet tall or as an erect shrub about 6 feet tall. They produce spikes of yellow flowers.