Bottle brush plants (Callistemon) are native to Australia and come in about 34 different species. The bottle brush grows naturally close to stream and creek beds or other moist areas. Its flower spikes bloom in spring and summer, resembling brushes used to clean out bottles. Bottle brushes are actually woody shrubs that grow up to 13 feet tall and are popular in gardens because they attract many types of birds, particularly hummingbirds. You can grow bottle brush plants indoors or out in your garden or landscape if you live in a warmer climate, with minimum winter temperatures above 20 degrees Fahrenheit.
Plant your bottle brush in an area that receives full sunlight and where soils are moist. Avoid heavily compacted or hard clay soils, as well as sandy or fast-draining soils. Work into the soil some peat moss and organic compost.
Water the plant once or twice each week during the growing season, soaking the soil thoroughly with warm water. Water when the surface soil begins to feel moderately dry to the touch.
Mist the bottle brush plant with warm water about three times per week during the growing season, if it’s container-grown. Place the plant outside in full sunlight during the summer.
Feed your bottle brush plant with a fertilizer for flowering shrubs that is lime-free in autumn, after the shrub is finished flowering. If you’re growing the plant in a container, fertilize it once every two weeks during the growing season with a water-soluble version of the same kind of fertilizer.
Prune your bottle brush plant lightly to control its size and shape. Prune the tips in late winter or early spring, before the new growth appears, and then prune the stems behind the flowers after they’re finished blooming.