Callistemons are endemic to Australia. The genus has around 30 species – all highly ornamental, evergreen shrubs and small trees. They belong to the myrtle family (Myrtaceae). Because of the fascination of the home gardener with this striking genus, there are now a large range of cultivars and hybrids available. The leathery leaves are linear or lanceolate and are arranged spirally round the stem. The showy flowers have long stamens and are massed in bottle-brush-like spikes, giving rise to the common name of ‘bottlebrush’. New growth is often a rich bronze or pink colour.
Callistemons are highly attractive to nectar-feeding birds. Most callistemon varieties prefer a moist, well-drained and slightly acid soil. They like a sunny position and some are affected by frosts. A bushier growth can be encouraged by pruning during the end of the flowering period. Propagation is by seed or, for some forms and cultivars, by striking from tip cuttings.
Callistemon pallidus or Lemon Bottlebrush grows to three metres and is found naturally in south-eastern Australia, mainly on ranges and tablelands. It is a dense shrub with grey-green to dark green leaves and silvery or reddish new growth. Cream to yellow bottlebrush flower spikes appear from late spring to summer. Some cultivars have red flowers. It is hardy and withstands winds, frost, periods of waterlogging and moderate coastal exposure.
Another of the smaller callistemons is Callistemon viridiflorus, also known as the Green Bottlebrush or Tasmanian Bottlebrush. It is endemic to Tasmania and has a fairly erect habit with stiff dark green leaves. The flowers are an attractive yellow-green. This species grows well in moist or even temporarily water-logged conditions.
Slightly taller at around 5 metres high is Callistemon speciosus or Albany Bottlebrush. This is also known as Callistemon glaucus. It is an ornamental shrub found in wet or swampy areas of southern Western Australia. The upright branches bear dull green or greyish leathery leaves. The deep red flowers appear in spring and summer. After flowering, the seed capsules remain along the stem. It is hardy and adaptable and responds well to pruning. It will also tolerate waterlogged soil.
The Scarlet Bottlebrush (Callistemon citrinus or Callistemon lanceolatus) is a dense bushy shrub with pink, silky shoots. Crushing the leaves produces a faint, lemon scent. It tolerates moderate coastal exposure and poor drainage. It is the parent of some lovely cultivars including ‘White Anzac’ (white flowers), ‘Burgundy’ (see below), ‘Jeffersii’ (dward with red-purple flowers) and ‘Angela’ (long pink flowers with white tips).
If you like your bottlebrushes to have gold-tipped flowers, then Callistemon brachyandrus or the Prickly Bottlebrush would be a good choice. It is a dense shrub with pointed leaves. The flowers are quite small, around 4cm long and are an orange-red tipped with gold. It is frost tolerant, drought resistant and grows well in warm to hot areas.
The Alpine Bottlebrush (Callistemon seeberi) has cream to yellow flower spikes 2 to 15cm long. Flowering is mainly from November to February. It is hardy, adaptable and responds well to pruning. It can be propagated from cuttings.
Callistemons hybridise readily and there are now some stunning varieties available. Some of the more striking types are:
* ‘Harkness’ which may grow to 6 metres. The new growth is a pretty pink with brilliant red flower spikes to 15cm long mainly from September to January.
* ‘Reeves Pink’ grows to 3 or 4 metres and has pink flowers tipped with gold.
* ‘Burgundy’ has deep red to burgundy bottlebrushes of 8 to 10cm long. These are produced in September to December and sometimes also in March and April. It is a selected seedling of C. ‘Reeves Pink’. It is hardy to a range of conditions and responds well to pruning.
* ‘Western Glory’ has masses of pinkish red flowers in spring and will often grace its owner with another display in autumn.
* ‘Little John’ is a dwarf variety with blue-green foliage and dark red flowers.
All Callistemon cultivars are commonly propagated from cuttings to retain the characteristics of the parents. Variations can occur if new plants are grown from seed.
Callistemons deserve a place in all Australian gardens. And, last but not least, kangaroos don’t eat them! So, if kangaroos check out your garden from time to time, and you want to feed the birds but not the kangaroos, try a few callistemons.