A member of the nyctaginaceae family, bougainvillea, also known as "4 O'Clocks," is a woody vine that thrives in tropical climates. A South American native, bougainvillea sports hot-colored pink, orange, red, purple, bi-color, and even white papery bracts resembling large butterflies massing on green, leafy vines. This exotic charmer can be grown outdoors as a perennial in zone 9 and above with proper care, or as an annual in cooler areas.
Choose a site with full sun and good drainage. Bougainvillea prefer a minimum of 65 degrees F for optimal growth and flowering. Intense light, consistent temperatures and extended nighttime hours are a recipe for sooner, more abundant blooms. Avoid sites that are exposed to high winds, and bear in mind that in zones 10 and above, your bougainvillea may grow to a height of 20 feet with an equal spread.
Prepare the soil for your bougainvillea bed by incorporating up to 3 inches of organic compost, such as pine bark, to a depth of 6 to 8 inches. Avoid amendments that retain excessive water, such as peat moss, as bougainvillea do not like constant soil moisture.
Plant bougainvillea vines near a support or trellis while they are becoming established. Set the vine at the depth it rested in the nursery, firming soil around the roots without compacting them.
Water deeply after planting and then only when the surface appears dry. Frequent, shallow watering will inhibit growth. Avoid excessive watering, as bougainvillea prefer moderately dry roots, but be aware of overly dry roots that may cause leaf dropping.
Fertilize in spring with a balanced 10-10-10 fertilizer, and then again in three months. Work granular fertilizer into the soil around the roots or apply a liquid fertilizer, avoiding the leaves and blooms.
Prune bougainvilleas after flowering, usually in the late fall or early spring, to maintain a smaller size specimen or to remove dead vine material. Also prune back suckers to make room for the primary trunks to thrive.