How to Winterize Bougainvillea
- 1). Remove any dead or damaged portions of the plant with pruning shears. Pull off any dead leaves that still hang from the plant. Remove any dead leaves or plant matter in the plant's container, along with any snails.
- 2). Spray the bougainvillea with a garden hose, starting from the top of the plant and moving downwards. This will remove any insects attached to the plant.
- 3). Bring the bougainvillea inside, into a greenhouse, garage, or other area protected from extreme cold temperatures. The plant will go dormant during the winter so it will not require a sunny spot.
- 4). Water the bougainvillea sparingly throughout the winter to prevent the roots from drying completely. Allow the soil to become dry to the touch between waterings, then water until the liquid comes out of the drainage holes in the bottom of the container.
Source...