Some plants have colorful but unusual flowers, making them interesting as well as attractive. The bottlebrush plant (Callistemon spp.) is that type of plant, producing cylindrical, fuzzy-looking, red flower clusters that give the plant its name. Bottlebrush is a sun-loving plant that puts on its best floral display in a sunny spot. It is hardy in U.S. Department of Agriculture (USDA) plant hardiness zones 8b through 11, depending on the species.
A sun-loving plant that is native to Australia, bottlebrush does best and produces the greatest number of flowers in a location exposed to full sun for most of the day. A few hours of late-afternoon shade won't hamper flowering significantly, but the plant is not a good choice for a fully shaded spot. The bottlebrush plant is a shrub that grows 3 to 20 feet tall, depending on the species, and can be pruned to grow as a small tree. Its flower clusters contain many tiny, red flowers encircling the stems, with each flower producing many long stamens that resemble fuzzy bristles.
Some bottlebrush varieties are compact and can do well as container plants, making it possible to overwinter them indoors in cold regions outside their hardiness zones. Those plants can be kept outdoors in a sunny spot from late spring through early fall but should be taken indoors when temperatures fall below 60 degrees Fahrenheit. During winter, a container-grown bottlebrush needs a brightly lit indoor spot and does well in a south- or west-facing window. When keeping the plant indoors, avoid placing it near a drafty door or window because cold air can damage the plant.
The bottlebrush plant is quite adaptable to any type of garden soil but grows best in a sandy loam that drains well. If your soil contains clay and tends to hold water, add some fine sand when planting a bottlebrush to increase the soil's drainage. The plant needs only an average amount of water and tolerates drought quite well once it is established in its site. In regions with cool winter weather, mulching the plant with a 2- to 3-inch thick layer of organic mulch can help protect its roots from winter damage. Watering it well as cold weather approaches also can prepare the plant for winter and help it survive without ill effects.
Several species of bottlebrush plant generally are available at garden centers. All thrive and bloom well in full-sun locations. The crimson bottlebrush (Callistemon citrinus), also known as lemon bottlebrush, is 3 to 12 feet tall while the stiff bottlebrush (Callistemon ridigus) is an erect shrub that can reach a height of 3 to 8 feet. Both plants have bright-red flowers. Crimson bottlebrush is hardy in USDA zones 8 through 10, and stiff bottlebrush is hardy in USDA zones 9 and 10. The weeping bottlebrush (Callistemon viminalis) grows as a small tree and reaches a height of about 20 feet tall at maturity. Its branches arch gracefully toward the ground, and its scarlet flower clusters hang from the tips of the branches, swaying in breezes. Weeping bottlebrush tolerates hot sun especially well and is hardy in USDA zones 9 through 11.