China Trade Bonsai Society of Southeastern Connecticut - Todd Hansen


Todd and Trees - Left to Right Chinese Elm, Japanese Elm, Korean Hornbeam, Water Birch, American Hornbeam and Trident Maple

It continues a cycle that began last fall. Days grew shorter and temperatures cooled as summer became autumn, and autumn slipped into winter. Chemical processes inside the tree drew the sugars and nutrition from the leaves, storing in its roots food for the spring. Then the leaves fell and the tree slept. On March 2, 2005, Todd Hansen, former president of the Bonsai Society of Greater Hartford, now Vice-President and Events Coordinator, Runner-Up of 2004’s Joshua Roth New Talent Bonsai Competition and student of Colin Lewis presented an extremely informative lecture focusing on one of the most neglected practices in the world of bonsai…Winter Pruning of Deciduous Trees.		Todd explaining winter pruning techniques while working on a Korean Hornbeam
Example of a “knot” formed by improper pruning and concentrated growth. Note the area circled is larger than its branch to the left.	Every spring, the cycle continues. Warm weather, longer days result in buds swelling followed by the rampant growth of spring. This can be literally thousands of buds on some species, and left unchecked, the bonsai becomes a bush inside of a season. The theory behind winter pruning: Remove unwanted growth BEFORE it starts, putting as much Done properly, it results in double (or more) the desired growth and helps prevent unsightly knots. Trident maple, hornbeam, hawthorn, and elm are excellent candidates for winter pruning. Birches and Japanese maples are not. Birches suffer too much natural dieback, and Japanese Maples can bleed even during dormancy, therefore reducing spring vigor.
The hardest part of winter pruning is deciding what to prune and what to leave. Start by removing any dieback. This cleans up the tree and allows time to “feel” the structure. Next, remember basic characteristics such as taper and internode distance separate good bonsai from bad. The tree should have good taper in all aspects. The trunk should narrow from base to crown. The largest branch is the first branch, with each successive branch getting gradually smaller. Branches taper from trunk to tip. Additionally, as ramification builds, so should the internodes get smaller. The smallest internodes are at branch tips while the largest are toward the trunk. Prune that material which does not support good structure or tree health. If two branches are in conflict, choose which to keep based on health, taper, and movement. An excellent book outlining these principles is: Basic Bonsai Design by David DeGroot.		Basic Taper with Decreasing Internodes
Wound after cut paste is applied	When winter pruning, drastic changes such as major branch removal should generally be done in the spring and not in the winter. Because of winter’s low relative humidity, wounds tend to dry out faster if not properly tended. For this reason, if a major branch is removed in the winter, use of a proper cut paste is essential to ensure healing. Cut paste (as seen in the figure to the right) resembles sticky gray modeling clay. This is different from undesirable graft paste, which looks more like roofing tar. The former is easily removed as the wound heals, whereas the latter is permanent and will stain the tree. Additionally, products similar to Preparation-H are said to increase healing when used in conjunction with the cut paste.
A few last thoughts in parting. Winter pruning is generally February and March, but can be done most any month after hibernation is set and before spring budding starts. When winter pruning a branch, leave the branch collar to aid in healing. Also, leave at least ¼” beyond the desired bud for dieback. Best of luck and happy pruning!



Winter pruning aids in developing the shape of the tree by forcing growth to the desired locations.