A genus of about 34 species, mostly Australian, but a few recorded in other countries. In more recent times the Callistemon genus has been (scientifically) merged into Melaleuca. Many though who work in horticulture however, still continue to use the term callistemon.
They range from shrubs to small trees. Most have showy bottlebrush-shaped spikes of flowers.
Flower colours vary considerably ranging from whites to yellows, pinks to reds, green and mauve.
They are generally very hardy, and adaptable. Most will tolerate some drought, and periods of waterlogging. Growth rates may be slow and sporadic under difficult conditions, to quite fast under good conditions. They are generally long lived. They are commonly used as screen plants, in windbreaks, as bird attracters or for their showy flowers. Smaller cultivars can be used in shrubberies, as groundcovers or in large tubs.
They appreciate watering during dry periods. Tip prune regularly to keep bushy, particularly when young. Prune just behind spent flower spikes, once flowering has finished unless seeds are desired. Feeding with slow release fertilisers and pruning off spent flowers may encourage two flowering periods per year. Caterpillars and stem borers are occasionally a problem. Propagate from seed, or from cuttings for cultivars.
C. citrinus – (Red bottlebrush) very variable species with both shrub and tree cultivars available. Tolerant of wet and dry soil conditions. Flower spikes are up to 12cm long.
C. pallidus – (Lemon bottlebrush) Tall, bushy, erect, small tree to 6m with cream to yellow flower 7cm long spikes from late winter to summer.
C. salignus – (Willow bottlebrush) Weeping small tree with papery bark and cream to yellow 5cm long flowers mainly in late spring.
C. viminalis – (Weeping bottlebrush) Weeping small tree with a hard and furrowed bark, and red flower spikes up to 10cm long mainly in spring and summer. Popular cultivars of unsure heritage:
C. ‘Dawson River Weeper’ - very wide spreading plant to 5m x 5m with a long flowering period.
C. ‘Eureka’ – believed to be a seedling of C. salignus origin. Erect shrub to 5m, young growth is pink, flowers are purplish-red up to 10cm long.
C. ‘Hannah Ray’ – to 4.5m with bright red flowers in late spring.
C. ‘Harkness’ – spreading plant to 5m x 5m with long 15cm red flower spikes usually borne in clusters.
C. ‘King’s Park Special’ – small tree 3-5m tall with long 13cm red spikes borne in clusters mainly in spring.