Bottlebrushes are members of the genus Callistemon and belong to the family Myrtaceae. They are closely related to paperbark melaleucas, which also have 'bottlebrush' shaped flower spikes. It is difficult to tell to which genus some species belong.
Botanists are currently closely studying these plants to determine how they are best classified. There are 40 species currently called Callistemon.
Most species are frost tolerant.
The popularity of bottlebrushes as garden plants commenced soon after European settlement and Crimson Bottlebrush.
Many species can tolerate (or thrive in) damp conditions, yet most are very hardy and will tolerate drought and limited maintenance. They grow well in a wide variety of soils, except those which are highly alkaline. Plants grown in full sun produce the best flowers.
Plants can be lightly pruned after flowering to keep them in shape. A low-phosphorus fertilizer should be applied in spring and autumn. Mulching will help retain soil moisture and reduce weed growth.
Many cultivars have been selected from natural variants and hybrids between species. Some of these are very good garden plants.