With their vibrant red blooms, bottlebrush plants (Callistemon citrinus) remain a popular addition to home gardens and landscapes. Not only do home gardeners love the rich, red flowers, but they also love how a bottlebrush tree attracts butterflies and hummingbirds. Bottlebrush plants usually thrive in USDA hardiness zones 8b to 11, as they love a mild climate. Once established, they require some maintenance but not a lot, providing another reason to love them.