Shaping a Standard
Train bougainvillea into a topiary form that looks like a tree.
With a little patience, you can train your bougainvillea to look like a tree. A tidily pruned bougainvillea standard—with a single strong straight stem as its trunk—will eventually boast a crown of colorful blooms.
It will take 2 to 3 years for a bougainvillea standard to reach its full glory. Begin by filling a large clay pot with well-draining potting soil. Push a long plastic or metal stake through the soil until it touches the pot's bottom. Three to 4 feet of the stake should stand above the soil. Remove all but one basal stem from a young bougainvillea plant and plant next to the stake. Use soft ties to secure stem to stake—it's very important that the stem be kept straight as it grows.
Continue tying stem to stake as it grows and pinch back (without removing) shoots along the stem. When the stem has reached the desired height, pinch back the growing tip and allow side shoots to grow to form the flowering head. Strip the remaining stems from the trunk area.
Every few weeks, pinch the canopy's side shoots to encourage new stems to grow and to keep the crown compact. Remove stems from the trunk as needed.