Bougainvillea (Bougainvillea spp.) is a genus of plant species in the four-o'clock (Nyctinaginacea) family, native to the tropics and subtropics of South America. Bougainvillea species are climbing or trailing vines, well known for spectacular floral displays and vigorous growth. Three of the 14 species in the genus, B. glabra, B. spectabilis and B. peruviana, are horticulturally important, with many hybrid crosses produced commercially.
Bougainvilleas are evergreen, woody vines with a sprawling, rampant nature, reaching variable size depending upon its supporting structure. Bougainvillea can spread between 15 and 40 feet. Its green leaves are simple, 2-to-4 inches long, and elliptic-to-ovate shaped. The small, white-to-yellow tubular flowers are not distinctive, but three large and colorful, petal-like bracts, up to 2 inches long, form the showy part of the bloom. Bougainvillea colors include white, purple, and many shades of red, pink, yellow and orange. Depending on the species, some bougainvilleas have a sharp, 2-inch long thorn in leaf axils, where the leaf meets the stem.
Bougainvilleas are occasionally trained as shrubs, but they are well suited to arbors, walls, fences and carports. Rapid growers, bougainvilleas require room to spread so growth doesn't become a problem. Bougainvillea vines can also be used in containers, above-ground planters and as houseplants if growth is controlled.
Bougainvilleas usually prefer full sun for the best flowering and sandy, well-drained soil. Bougainvilleas are not salt or alkaline soil tolerant. They require frequent pruning but withstand it well. Texas A&M University Extension recommends cutting back shoots to 18-to-20 inches for the best blooms, as well as application of half-strength water soluble fertilizer. Over-fertilizing, however, promotes foliage growth over blooming. Bougainvilleas are hardy to USDA Zone 9, but some hardier varieties may be grown in slightly colder zones.
Cultivar 'Barbara Karst' has bright red to bluish-crimson bracts and tolerates shade and heat. 'Sundown' is an apricot bougainvillea. 'Texas Dawn' has huge clusters of small, pink blooms, and 'Surprise' has pink-and-white blooms and is easy to grow.
Be careful when trimming bougainvilleas because of their sharp thorns (present on some species). Bougainvilleas are relatively pest free, but caterpillars might bother new growth. Commercial insecticidal soaps control a variety of insect pests.