The weeping redbud (Cercis canadensis ‘Pendula’) is a highly valued ornamental tree, recognized for its distinctive cascading, umbrella-like canopy. This unique form is often achieved through grafting, making careful and precise pruning necessary for the tree’s long-term health and structural integrity. Pruning maintains the weeping habit, promotes better air circulation, and prevents weak, problematic growth. Understanding these specialized techniques encourages vigorous growth and the characteristic spring flower display.
Optimal Timing and Necessary Tools
The best time for structural pruning is in late winter or very early spring, while the tree is dormant and before the buds swell. Pruning during this window minimizes the tree’s natural tendency to “bleed” or exude sap from fresh cuts, which is common in redbuds. While major shaping is reserved for the dormant season, removing dead, diseased, or damaged wood can be done at any time of year.
Minor shaping and thinning can be performed after the tree finishes spring flowering, but keep this minimal to avoid removing next year’s flower buds. Pruning tools must be sharp and clean to ensure smooth cuts that heal quickly and prevent disease entry. You will need bypass pruners for smaller branches, loppers for branches up to one and a half inches, and a pruning saw for anything larger. Sterilizing the blades with a 70% isopropyl alcohol solution between cuts, especially when removing diseased wood, helps prevent the spread of pathogens.
Maintaining the Weeping Structure
The primary goal when pruning is to preserve the strong central leader and the overall cascading, dome-like form. The weeping habit is defined by branches that arch outward and downward from the main trunk, forming the canopy’s “ribs.” Focus on removing any branches growing inward toward the center of the tree, as this causes congestion and poor light penetration.
To improve pedestrian access or prevent lower branches from touching the ground, you can strategically raise the canopy. This involves removing the lowest branches back to the main trunk, but do this gradually over several seasons to avoid stressing the tree. Avoid indiscriminately cutting off the top of the canopy when managing height, as this destroys the graceful arc of the weeping branches. Instead, prune the main leader back to a strong, outward-facing side branch to control vertical growth and encourage lateral spread.
Specific Cutting Techniques
All cuts should be made with a clear understanding of the branch collar, which is the swollen tissue where a branch meets the trunk or a larger limb. This collar contains specialized cells that facilitate wound closure, so cuts must be made just outside of it without causing damage. Cutting too close to the trunk (a flush cut) wounds the tree’s main support structure, while leaving a stub cut invites decay and pest infiltration.
Thinning cuts are the most common technique, involving the complete removal of a branch back to its point of origin. This practice opens the canopy to sunlight and air, which is beneficial given the redbud’s susceptibility to fungal diseases. When performing a thinning cut, remove the entire branch back to a lateral branch or the main trunk, ensuring the cut is made just beyond the branch collar.
Heading cuts, which shorten a branch by cutting it back to a bud or smaller side branch, should be used sparingly on weeping trees. This technique is employed only to redirect growth away from a congested area or to manage a competing leader. If a heading cut is necessary, make it at a 45-degree angle approximately a quarter-inch above an outward-facing bud. For removing larger branches, utilize the three-cut method: an undercut made a foot away from the final cut, a top cut to remove the bulk of the weight, and a final cut just outside the branch collar to prevent bark stripping.
Managing Unwanted Growth
Two types of vigorous, unwanted growth frequently appear on grafted weeping redbuds and must be removed promptly: basal suckers and water sprouts. Basal suckers are shoots that emerge from the rootstock below the graft union, often visible as a slight bulge on the trunk. If left to grow, these suckers will eventually out-compete the desired weeping cultivar, producing the characteristics of the non-ornamental rootstock.
Water sprouts are fast-growing, vertical shoots that appear along the limbs or main trunk, often in response to heavy pruning or stress. These shoots are structurally weak and detract from the tree’s weeping form. Both suckers and water sprouts should be removed as soon as they are noticed to prevent them from diverting energy away from the established canopy. Suckers should be traced down to their point of origin and cut or torn off flush with the root or trunk. Water sprouts should be cut flush with the limb or trunk from which they originate, taking care not to leave a stub.