Bonsai Reference - Winter Care for Bonsai
The fall equinoctial season, with its equal days and nights, changes many things. It is not only a turning point in the growing
habits of plant life. but in some climates, there is still a period in which spurts of new growth continue before the
plant enters its fall dormancy. Insect activities and damage is on the rise. Chewing insects seem to gorge themselves before
winter arrives. Watch for evidence of snails and slugs since they destroy young trees by girdling the trunk or branches.
There is still time to give your bonsai a last good feeding during the fall months. Continue using a fertilizer with little or no
nitrogen. Rely on a formula that is high in potash and phosphorus. Most fruiting and flowering bonsai will benefit from this type
of mixture. Specifically, azaleas, crabapples, umes, and pomegranates will improve after these late feedings. The changing
colors on the deciduous trees tell you that the growing season is over. Fall foliage greatly enhances the beauty of the trees at this
time of year. Concentrate on the liquid ambers, maples, ginkgoes, hornbeans and zelcova for the best colors.
Cut back on your watering schedule, but do not allow the trees to dry out. As the length of the day's sunshine is shortened, the
trees require less water. A balance must be maintained between the minimal watering and the loss of moisture by transpiration
during intermittent hot spells.
Transplanting is permissible at this time of year, specifically bamboo, boxwood, conifers (pines), hornbeans, cotoneaster,
podocarpus, privets, pyracantha, wisteria, willows, and most varieties of deciduous trees. (Reference: Bonsai Techniques #1,
by John Naka, published in 1973). The key to safe repotting is to minimize any root disturbance and to exclude any severe
pruning of any kind. Trees can be transferred into larger or different con-tainers. If in doubt about the health or condition of a
tree, wait another month or until spring to repot. Wire cuts can occur during the next few months. While winter growth is limited
during the dormancy period, the woody portion of the tree contin-ues to lignify and harden. Be sure to check all wires on
branches and around the trunk. Remove any tightening wire. This is a particularly good time to apply some new wire since the
trees have shed the mantle of leaves which have hidden the branches. Now they are exposed for a proper redesign. Be careful
when applying new wire since the branches are quite brittle when the sap is not circulating in the wood.
Keep most deciduous trees out of the bright sunshine, especially those that had been defoliated a few months ago and have
new young leaves. Even as they mature and drop for natural fall defoliation, they are quite tender. Keep them cool and moist to
prevent additional winter resprouting.
Keep any long shoots trimmed. Pinching and pruning is still an important training requirement. Do not do any severe pruning,
however, since the slow down of winter growthwill not permit the tree to recover from any trauma. Pines should be trimmed by
removing old, dead needles and reducing candle sizes. Trim all deciduous trees to remove long internodes of summer growth.
Remove old hanging fruit and seed pods. If berries con-tinue to hang on they may be allowed to stay until spring since they do
not drain any strength from the tree.
Continue to rotate all trees to maintain even exposure to the limited light conditions. This is the time for trees to store food for
winter dormancy. It is also the time to keep trees free of accumulated trash which could be the home for winterizing insects and
fungus. Keep all trees open, airy and exposed to the light.
Keep up applications of an all-purpose insecticide and fungicide. Insect, such as aphids continue to suck sap and can be best
controlled with an oily or systemic pesticide. Watch for signs of fungus infection such as dark spots on needles and leaves or a
white powdery substance at the base of the leaves. Fungus infection can be prevented with applications of a cop-per based
Bordeaux or Benomil. Bravo or Daconil is effective for above ground infections. Subdue is best for the subterranean infections.
You may think you've read this information before, and perhaps you have, but repetition is the best reminder to keep you
advised and prompt you to act.