The bottlebrush tree, or Callistemon, is a midsize evergreen with distinctively shaped blossoms. As its name implies, the flowers are shaped like the cylindrical brushes used to clean baby bottles. It is native to Australia but also grows in areas with temperate climates. There are several varieties of this tree, including a weeping form and dwarf sizes. Most cultivars have red, pink, or white flowers.
Standard bottlebrush trees grow to an average of 15 feet (4.5 meters) tall, although some specimens can grow slightly taller. Each has a typical tree shape with an average canopy spread. Callistemon viminalis is the weeping form, closely resembling a weeping willow. This variety can grow to 20 feet (6 meters) tall, with long branches drooping toward the ground. Dwarf bottlebrushes are more of a shrub than a tree, growing to only 3 feet (1 meter) tall.
Aside from their traditional flower colors, newer varieties of bottlebrush trees have been developed that bloom in shades of purple, yellow, and green. Hummingbirds and butterflies are both attracted to the colorful flowers. Bees like the blossoms, as well, and will continue to visit the flowers even after they have dropped from the tree. People are often stung as a result of walking barefoot on the fallen flowers.
This tree prefers subtropical climates and can tolerate only short periods of frost. It can be killed by exposure to freezing temperatures. Aside from that, the bottlebrush tree is a fairly hardy tree that will grow in sandy or rich soils. Although it prefers regular watering, it will survive short periods of drought. Callistemon is tolerant of salt exposure and is a good choice of tree for areas near the ocean.
Bottlebrush trees are usually grown from cuttings as most cultivated specimens are hybrids. Trees grown from hybrid seeds may not be true to the parent and may result in a tree that is susceptible to pests and diseases. Rooted cuttings should be planted in the late summer in areas that receive full sun. Mulch placed around the planting help the soil retain moisture.
The soil should be kept moist until the new plant is established and shows new growth. Once a Callistemon tree is established, it is easy to care for. It will only need supplemental watering in times of extended drought. They do not require it but will benefit from a spring and summer application of a slow-release 8-8-8 fertilizer.