The bottle brush tree (Callistemon) is a small evergreen that can can be grown as a shrub or tree. The tree is a native of Australia. It is favored as a garden specimen for its distinct spike flowers that appear in red, purple, green, yellow or pink. The flowers are favored by hummingbirds, bees and butterflies. The tree grows between 6 to 15 feet tall. It is a subtropical tree that cannot withstand continued cold temperatures for very long. The flowers form small clusters of fruits that can hang on the tree for years before opening up to seed.
Plant the bottle brush tree in a location that offers full sun. A location beside a house, fence or wall that affords wind protection but also offers full sun is ideal. The bottle brush has very weak and brittle wood so it can easily sustain damage in a windstorm. The protection of a building, fence or structure can help protect the tree in a strong storm.
Choose a location that offers well-drained soil conditions. The bottle brush does not like to be planted in standing water because it can easily suffer root rot. Mix 50 percent peat moss with 50 percent garden soil to offer a rich base in which to plant the tree.
Water the tree regularly to prevent drought conditions. The bottle brush tree prefers moist soil that is not waterlogged.
Prune the bottle brush tree lightly after flowering. Simply prune back a few branch ends to maintain the tree's size and overall appearance. Bottle brush trees do not require extreme pruning.
Fertilize the bottle brush tree in March, May and September. Use a light fertilizer for flowering trees such as a 6-3-2. Apply 1 to 3 lbs. depending on the tree's size around the base of the tree and outward toward the tree's drip line. Water the tree thoroughly to water the fertilizer in.