Site Selection

• Bougainvilleas are wind-resistant, drought-tolerant and salt-tolerant. For best flowering, they require full sun and well-drained, slightly acidic soil. Bougainvillea will quickly drop bracts when planted in a shady location. In general, they thrive in hot and dry climates with year-round temperatures ranging from 65 to 95 degrees Fahrenheit. Bougainvillea are ideally suited for areas with southwestern exposures, which provide the most intense heat throughout the year.
  
  

Frost Damage

• The relative degree of injury sustained by bougainvillea is proportional to the duration and frequency of cold weather as well as the temperature conditioning of the individual plant. For example, a very sudden and intense cold snap will inflict greater damage on a plant used to mild temperatures than on a plant that's used to frequent ups and downs. Whole branches or entire plants may die from cold weather. Usually within 24 hours of a frost, severely damaged parts of a plant will turn blackish-brown. Shoots, buds, leaves and flowers will wilt and fall off. Plants damaged to a lesser degree will have leaves that appear burned. Young bougainvillea are particularly at risk and may die when exposed to as few as four hours of freezing temperatures.
  
  

Frost Protection

• Select a slightly more cold-hardy cultivar, such as bougainvillea glabra, if you live in an area that experiences frequent winter frosts. When frost is forecast, move containerized plants indoors and cover outdoor bougainvillea with sheets or blankets during the night. If the plant is too large or if covering is otherwise not feasible, consider other protection measures such as mounding soil or mulch over roots, placing electric lights (such as Christmas lights) in the canopy or running sprinklers over the plants during frost warnings. Prune outdoor bougainvilleas and place them in an indoor container during the coldest months of the year. Alternatively, some people choose to treat the plants as annuals, allowing it to die in the winter.
  
  

Frost Damage Solutions

• Mature. well-adapted plants typically do not sustain permanent damage from frost. With pruning, most cold-damaged plants should rebound. Fortunately, bougainvilleas respond well to pruning. In fact, in the absence of regular pruning the plant form is likely to become tangled, overcrowded and pest-ridden. Trim off any frost-damaged portions of bougainvillea, but not until the threat of any additional damaging cold weather has passed. For the areas where bougainvillea grow naturally, March is usually good month. Trim only damaged portions of the plant at this time, reserving more severe pruning until after the next blooming period.