Bougainvillea is a vigorous plant, prized for its showy, colorful bracts. While it has a vine-like growth habit, it is not a true clinging vine, lacking the tendrils or adhesive pads needed to attach itself to a surface. To achieve vertical growth and dense coverage, a gardener must actively train and secure its long, woody canes to a support structure. Trellising manages the plant’s substantial size and weight, guiding its naturally sprawling form into a disciplined, upright display.
Choosing the Best Support Structure
Bougainvillea’s stems lignify quickly, developing into heavy, woody canes that exert considerable force on any support. Selecting a robust structure is necessary to prevent collapse once the plant reaches maturity. Ideal materials include heavy-duty metal such as galvanized steel or wrought iron, or sturdy, pressure-treated wood that can withstand the elements and the plant’s aggressive growth.
Flimsier options like plastic netting or thin wooden lattice are unsuitable, as they will buckle or break under the plant’s mature mass. The trellis must be securely anchored to a solid base, such as a wall or deeply set posts, before planting or training begins. This ensures the structure can bear the weight of a mature bougainvillea, which can easily reach heights of 15 to 40 feet depending on the variety and climate.
Initial Pruning and Preparation
Preparation should occur in late winter or early spring, just before the new growth cycle begins. The first step is structural pruning to remove any dead, damaged, or weak wood, directing the plant’s energy toward healthy growth. This trimming helps open up the plant’s interior, improving air circulation and light penetration, which are necessary for health and abundant flowering.
Next, select two or three of the strongest, most upright canes to serve as the main leaders for the permanent vertical structure. All other smaller branches and side shoots, especially those growing low near the base, should be removed. This focused removal encourages the plant to channel growth into the chosen leaders, promoting a strong upward trajectory rather than a bushy habit. Pruning cuts should be made just above a leaf node to stimulate new, upward growth.
Step-by-Step Training Techniques
Once the support structure is in place and the plant is prepared, the chosen leader canes must be gently secured to the trellis. Use flexible, soft tying materials such as fabric strips, twine, or cushioned plant ties, as these will not cut into the stems as they grow and thicken. Never use wire or thin plastic ties, which can cause girdling and severe damage to the woody growth.
The ties must be looped loosely around the stem and the trellis to allow for future expansion of the cane’s diameter. Guide the leader canes not straight up, but at a slight angle or horizontally along the trellis bars. Bending the canes horizontally helps break apical dominance, which is the tendency for growth to occur only at the tip of the stem. This horizontal training encourages lateral buds to sprout, producing numerous flowering side shoots and maximizing the display of colorful bracts. During the active growing season, check the new, flexible growth frequently, securing any stray shoots before they harden into rigid, untrainable wood.
Long-Term Maintenance of Trellised Bougainvillea
Maintaining a trellised bougainvillea requires consistent attention to manage its rapid, aggressive growth and preserve its trained form. The plant will continuously send out new, vigorous shoots that must be checked and adjusted to keep the canopy flush against the support. Corrective pruning, often done in the summer, involves pinching off the tips of new growth or trimming back any shoots growing away from the trellis to maintain the desired shape and density.
Structural pruning is best performed in late winter or early spring before new buds form, cutting back long, unmanageable stems to an appropriate size. Established, woody canes may need their ties inspected and adjusted annually to ensure they are not constricting the stem or allowing the plant to pull away from the support. This continuous management ensures the plant remains a vibrant, contained vertical feature rather than an unruly, sprawling thicket.