Bougainvillea (Bougainvillea spp.), native to coastal Brazil, is hardy only in U.S. Department of Agriculture plant hardiness zones 9b through zone 11, nevertheless is grown throughout USDA zones 8 through 9. Where it cannot grow as an evergreen year round, gardeners grow it in containers and as annuals. Its popularity is due to its raucous display of color and rapid growth habit.
Left to its own devices in its native range, bougainvillea vines tumble over fences, walls and shrubs in eruptions of bright red, pink or purple bracts surrounding tiny white flowers. Peak bloom occurs during Southern Hemisphere summer -- December through March -- in areas where bougainvillea grows unchecked. Typically, though, the vine’s undisciplined growth is controlled by trimming, pruning and pinching, which changes the growth pattern to encourage shrubbier growth and more frequent flowering. Pruning after bloom encourages bloom. Plants grown as annuals in zones below 9b live on through cuttings rooted and grown indoors throughout the cooler months.
Bougainvilleas are aggressive growers, but their growth depends on the cultural conditions in which they find themselves. They thrive in full sun with daytime temperatures between 75 and 95 degrees Fahrenheit and nighttime temperatures in the mid-60s. They grow best in rich, well-drained soil with an acidic pH between 5.5 to 6.0, typical of many tropical plants that come from areas where soil is rich in humus and decaying matter. Given perfect conditions, bougainvillea can grow 3 to 4 feet a season and produce many side branches. With judicious side pruning, a main leader can grow even faster.
Keeping plants in bloom helps keep plants smaller because bougainvilleas grow most robustly when they are not in bloom. Pinching ends after bloom encourages further bloom production. Container plants that must be taken indoors during winter require pruning and pinching after bloom in summer and pinching when taken back outside in the spring. By trimming and pinching when the plant is making its strongest growth, it is kept more compact and productive.
Bougainvillea growers figure 12 to 16 weeks to bring a growing cutting to a plant large enough to plant in a 1-gallon container or in a hanging basket and use high light levels near 4,000 foot candles and drought stress to force flowering. To encourage flowering in home gardens, bougainvilleas belong in full sun and fast-draining soil. Slow-release fertilizer or regular applications of 1-1-1 or 2-1-2 fertilizer will nourish bougainvilleas, but over-fertilizing can slow growth. Growers and professional landscapers use chemicals such as benzyladenine and dikegulac sodium, which encourage faster growth; and chlormequat, ncymidol and paclobutrazol, which retard growth.
- Alabama Cooperative Extension: Vine for the Alabama Landscape
- University of Florida IFAS Cooperative Extension Service: Bougainvillea spp.
- Clemson University Extension: Bougainvillia
- University of Florida IFAS Extension: Bougainvillea - A Robust and Spectacular Climbing Vine
- University of Hawaii Cooperative Extension Service: Bougainvillea
- University of Florida IFAS Extension: Warm Climate Production Guidelines for Bougainvillea
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