Callistemon is a genus of trees and shrubs native to Australia and New Caledonia. These plants have adapted to climate conditions roughly equivalent to those found in United States Department of Agriculture (USDA) zones eight through ten. Some species are drought resistant, while others may require moister conditions, especially while they are getting established. Callistemon is often stocked at garden supply stores and specialty cultivars, such as versions with unusually colored flowers, can be ordered by request.
Known colloquially as bottlebrushes, Callistemon species are evergreen, with pointy green leaves and distinctive inflorescences with highly visible stamens and hidden petals. The flowers look like giant bottlebrushes and are often bright red or white, making them very easy to spot. Depending on the species, the final height of a plant can vary, and people may trim or train them to grow slightly taller or shorter than they would in nature.
In Australia, Callistemon species have adapted to woodland environments. Drought tolerant species can handle relatively coarse soil and dry conditions, and make an excellent choice for low water gardens, rockeries, and Mediterranean landscaping. Other species are more water intensive and benefit from richer soil with reasonably high moisture retention. The water requirements of individual plants should be readily available, allowing gardeners to select the right plant for their needs.
These plants can be cultivated from seeds or cuttings. They do very well as standalone garden features in a tropical or subtropical garden, and look especially good against solid backdrops like walls or dense dark green evergreen shrubs. Masses of Callistemon species can also be planted and trained to create a hedge or privacy screen, if desired. Gardeners should be aware that the flowers can get messy, depositing stamens on the ground under the trees in spring and summer, and the seeds will also scatter to the ground and make a mess.
When growing from seeds or cuttings, it can be advisable to use a greenhouse to support the plant while it gets established. Once a seedling is starting to thrive, it can be introduced to the outside in its container to grow accustomed to the outdoor conditions. After several days outside in the container, the seedling can be transplanted to a final destination. In cooler climates, mulching in the winter to protect the roots is advised. These plants are not generally tolerant of hard frosts and it is a good idea to cover young plants if a frost is predicted.