Bougainvillea plants are celebrated for their vibrant, colorful display. Unlike true clinging vines that use tendrils or adhesive pads, bougainvillea is botanically a woody, thorny scrambler that lacks the ability to attach itself to a surface. Achieving a vertical cascade of color requires providing a sturdy structure and consistently securing the flexible, new growth. By understanding this growth habit, gardeners can transform this sprawling shrub into a magnificent vertical accent with proper training and strategic pruning.
Selecting the Necessary Support System
The first step in training bougainvillea to climb is installing a robust support system capable of bearing the plant’s substantial weight and vigorous growth. A mature bougainvillea can become quite heavy, requiring a structure that is securely anchored to the ground or a wall. Suitable options include heavy-duty metal trellises, wooden arbors, or wire grids constructed from materials like 12-gauge wire.
When attaching the support to a structure like a wall, maintain a gap of approximately two to four inches between the support and the wall surface. This spacing allows for adequate air circulation, which helps prevent fungal diseases, and provides necessary room to maneuver and tie the branches. The structure’s design should have horizontal elements to offer numerous points where the plant’s stems can be secured as they grow upward.
Step-by-Step Training and Securing Techniques
Training the bougainvillea begins when the plant is young and its branches are still pliable, typically when the new, green growth emerges. The goal is to select specific stems, known as leader branches, to establish the vertical framework that will cover the support structure. Focus the plant’s energy on the desired upward trajectory by removing or redirecting any branches growing horizontally or inward.
The physical act of securing the stems must be done gently to avoid snapping the brittle, older wood. New shoots are flexible and should be carefully guided and tied to the support structure at regular intervals, such as every 12 to 18 inches. Use materials that are soft and flexible, such as cloth strips, garden twine, or specialized plastic ties. Avoid using thin wire or string that could cut into the bark.
When securing a stem, ensure the tie is looped loosely around the branch and the support, leaving a small amount of slack. This allowance is essential because the stem will thicken over time, and a tight tie can girdle the branch, constricting the flow of water and nutrients. This process must be repeated regularly throughout the active growing season, continually weaving new runners through the support and securing them to maintain the vertical structure.
Pruning for Vertical Growth and Structure
Pruning is a tool used to reinforce the climbing structure and encourage a dense, colorful display. Major structural pruning should occur in late winter or early spring, just before the beginning of the active growth cycle. This timing allows the plant to direct its spring energy into producing new shoots that can be trained vertically, as the colorful bracts form on new wood.
To promote fullness along the climbing path, gardeners should employ “tip pruning” or “pinching.” This involves removing the soft, growing tip of a branch, which stimulates the plant to produce side shoots from the nodes below the cut. Tip pruning encourages a denser network of branches that will fill out the support structure, rather than leaving a long, bare stem with blooms only at the top.
Throughout the growing season, remove any errant branches that grow aggressively away from the support or begin to cross back into the plant’s center. This removal of horizontal or inward-growing stems helps maintain a streamlined, vertical form and improves air circulation. Due to the presence of sharp, woody thorns on most bougainvillea varieties, wear thick gardening gloves and long sleeves during any pruning or training activity.