Notching is a technique used to influence a tree’s growth pattern by encouraging the development of new lateral branches. This method involves making a shallow cut into the bark just above a dormant bud to improve a tree’s structure, balance a lopsided canopy, or fill in areas that lack branching. This physical alteration manipulates the tree’s natural hormonal signals, prompting a dormant bud to awaken and form a new shoot in a desired location.
The Horticultural Mechanism of Notching
The effectiveness of notching is rooted in overcoming apical dominance, a natural process controlled by plant hormones. The terminal bud produces high concentrations of the growth-inhibiting hormone auxin, which moves downward through the vascular tissues, suppressing the growth of lateral buds below it.
Notching involves making a cut that severs the phloem tissue, the primary pathway for auxin transport. Creating this small wound just above a dormant bud interrupts the flow of auxin, blocking it from reaching that specific bud. This interruption relieves the lateral bud of hormonal suppression, signaling it to begin active growth and form a new branch.
Optimal Timing and Preparation
Selecting the correct timing for notching is closely linked to the tree’s natural growth cycle, maximizing the chances of a successful bud break. The optimal window is typically in late winter or early spring, just as the tree is beginning to move sap but before the buds swell or break dormancy. Making the cut about two to four weeks before the period of full bloom often offers the highest success rate.
Preparation begins by identifying the exact dormant bud you wish to activate, choosing one that points toward the needed growth direction. Select a proper tool, such as a sharp, clean grafting knife, a specialized notching tool, or a hacksaw blade, depending on the branch size. Tool sterilization is mandatory before making any cuts to prevent the transfer of pathogens into the fresh wound. Tools should be wiped down with isopropyl alcohol or a diluted bleach mixture between each tree.
Step-by-Step Guide to Executing the Notch
The physical action of notching must be precise, aiming to cut through the bark and cambium layer without causing undue stress. The cut should be centered directly above the chosen dormant bud, leaving no more than a quarter-inch space between the bud and the notch. This placement ensures the wound intercepts the downward flow of auxin before it can inhibit the bud.
The depth of the cut is critical for success. It must penetrate all layers of the bark and the thin cambium layer beneath it, reaching the hard, inner wood. Failure to reach the cambium means the hormone flow remains intact, while cutting too deeply risks girdling the branch. The notch width should be narrow, typically between 1/8 and 1/4 inch, ensuring the vascular connection is severed while facilitating quick wound closure.
A clean cut that removes a small sliver of bark is preferable to a simple slit. Removing the tissue ensures the severed ends do not immediately reconnect and restore the auxin pathway. Making a clean, decisive wound with a sharp tool is important, as ragged edges delay the tree’s natural healing process. The resulting wound should expose a small section of the lighter-colored wood beneath the cambium, confirming the interruption necessary to release the bud.
Monitoring and Follow-Up Care
After notching, the bud should be closely monitored for signs of swelling and breaking, which typically occurs within a few weeks to a couple of months. Successful notching results in the bud swelling and pushing out new shoot growth, indicating the hormonal inhibition has been overcome. Note that not every notched bud will produce a new branch, as some species are more responsive than others.
The tree requires adequate resources to support the development of the new branch during this active growth period. Ensure the tree receives sufficient moisture and nutrients through regular watering and the application of an organic mulch layer around the base. The small wound should also be observed for any signs of disease, such as ooze, discoloration, or fungal growth. Once the new branch begins to grow, manage it with future pruning to ensure it develops a healthy, wide-angled attachment.