Stroll through a tropical garden and you'll most likely see the colorful bougainvillea nodding to you from overhead. Bougainvillea is a shrubby vine native to South America and a member of the Four O'Clock family (Nyctaginaceae). It grows in USDA hardiness zones 9 to 11. It can reach 20 feet tall, and its thorny, stiff canes clamber up walls and over trellises. Caring for bougainvillea is fairly easy if you have the right conditions to do so.
Plant your bougainvillea 6 to 9 feet apart in an area that receives full sun. Low light or shady areas will cause bougainvillea to drop its bracts. Like poinsettia, bougainvillea's colorful "petals" or "flowers" are really modified leaves below the inconspicuous true flowers, according to Clemson University Extension.
Bougainvillea prefers hot, dry conditions and does not like to have its "feet" wet. It grows best in a rich soil with a pH of 5.5 to 6.0, but it survives even in nutrient-poor soil if it is not kept too moist. Because bougainvillea can suffer from girdling caused by high winds rubbing the stems together, plant it in a protected area.
Water weekly until the plant is established. After that, water only when the soil is quite dry. It's better to slightly underwater than overwater.
Fertilize by amending the soil with compost or by using slow-release fertilizers with a moderate amount of nitrogen. Too much fertilizer can suppress blooming. According to the University of Hawaii Cooperative Extension Service, bougainvillea needs regular fertilizing with formulations having NPK ratios of 1:1:1 or 2:1:2, and half-rate applications of soluble minor elements help prevent leaf chlorosis (yellowing).
Prune your bougainvillea regularly to keep it from becoming tangled and overcrowded. Flowers bloom on the plant's new growth, so pruning is the key to a showy plant. Prune when the blooms have stopped. Remove dead wood, straggling shoots and any suckers at the plant's base.