Winter work on bonsai: rest, care and preparation for growth

Winter is a time of silence, but also of mindfulness. While the tree rests, you lay the foundation for a healthy growing season. In December, the work shifts from growing to observing, assessing, structuring, and protecting . In winter, you lay the foundation for what will become visible in spring. Conifers, deciduous trees, and azaleas each require their own approach during this period.
Below you'll find a brief summary of all types of winter work, followed by a further explanation of the options for each type.

Structure control & winter pruning

During the leafless period, you can see the branching more clearly than in any other season. Light corrections are possible now, but heavy pruning is best done in spring. It's best to prune maples and beeches carefully now, as they develop a lot of sap pressure in spring.

This is the time to:

• remove weak or crossing branches;
• to take back excess buttons;
• to touch up old pruning wounds;
• primary and secondary branch structure to be assessed for balance.

Recommended tools: sharp pruning shears, cutting pliers, concave pliers (hollow pliers), knob pliers, fine bud shears.
What you better postpone: heavy pruning in species that can bleed (such as Acer palmatum ), unless strictly necessary.

Wiring & controlling motion

December is an excellent month for wiring branches. The tree is dormant and less susceptible to damage. Branches hold their shape better because the wood is under less sap pressure. Shaping and wiring is possible, but root work can wait until early spring.

• thread grips better on coniferous and deciduous trees without leaves;
• branches break less quickly with even pressure;
• Corrections made now often remain more stable after spring.

Recommended materials: aluminum and/or copper wire, wire cutters, raffia for strong bends.

Working on dead wood (jin & shari)

In December you can easily work on dead wood, provided you are careful with species that retain moisture in soft tissue.

What is possible:

• refine existing jin and shari;
• remove old fibers;
• minor shape corrections.

What not to do: working deeply or aggressively into the living wood — this is best done in the warmer months when the tree recovers more quickly.

Recommended tools: jin tongs, carving knives, small floats, brushes, and possibly fine carving tools.
Post-treatment: light layer of lime sulfur on dry days.

Preparing for repotting

The actual repotting season comes in February–March, but you can start preparing now so you can get started right away when spring suddenly arrives, and sieving is a wonderful winter chore!

• Akadama seven (for structure);
• Mixing Kiryu and pumice for conifers;
• select and clean pots;
• have root rakes, spatulas and wire ready.

Watering & nutrition

In December, little water is used, but constant vigilance is essential:

• do not water until the topsoil is almost dry;
• avoid water in bowls during periods of frost;
• no fertilization in this phase.

Winter protection

Cold is good for trees, but prolonged frost can cause problems, especially with small containers.

• Place in a sheltered place during night frost.
• Use fleece around the pot, not over the tree.
• Open the cold greenhouse on sunny days (for ventilation!).
• Protect the roots, not the crown: the crown is hardier than the contents of the pot.

Recommended equipment: winter fleece, wooden coasters, baskets or crates for group protection.

WINTER WORK BY TYPE IN MORE DETAIL

Conifers : Shaping in Winter

Conifers such as Pinus , Juniperus, and Chamaecyparis are ideal for winter work. Wiring and shaping can be done well now, and dead branches can be removed without risk. During this period, the sap flow is largely at a standstill, meaning the branches temporarily contain less moisture and tension. This makes the wood slightly less elastic and therefore easier to maintain after wiring.
Because the needle growth is dormant, the internal branch structure becomes more visible: no new shoots to obstruct the view, but a clear picture of the trunk and branching. This makes winter ideal for assessing proportions and defining lines. Dead or unwanted branches can be removed without risk, but heavy pruning is best left until spring. Old wiring can be replaced, but heavy pruning or root work is best left until early spring, once the roots become active again. Note: during severe frost, wood and needles become more brittle and susceptible to damage. Always wait until early spring to repot, just before root activity increases.
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Deciduous trees at rest: structure visible

The fact that deciduous trees like Zelkova , Acer, and Fagus lose their leaves in winter isn't a loss, but an opportunity: because the tree invests all its energy in the trunk and roots, the branches fully open up. The structure, buds, and branch angles are now clearly visible – much better than in summer. This makes winter the ideal time to critically assess the trunk and branching. With species like Acers and Ulmussen, bud development is clearly visible, allowing you to plan which growth will strengthen the crown in spring. Unwanted shoots, cross branches, or water suckers can be removed, as long as these are minor corrections. Avoid heavy pruning: with species like Acers, sap pressure in early spring can lead to bleeding if pruned too early or too heavily; minor corrections are generally safe. Always postpone repotting until the buds begin to swell, because then the roots will actively grow again and recovery will be optimal.
Discover the non-flowering deciduous trees in our collection›
Discover the flowering deciduous trees in our collection ›
Discover the fruit-bearing deciduous trees in our collection ›

Azaleas : plans for June blooms

Satsuki azaleas are highly responsive to timing and don't require any major interventions in winter. Sap flow is minimal in winter, so interventions such as pruning or repotting would weaken the tree. Repotting too early weakens the roots and can cause flowering to stop. After flowering, in June, is the time for pruning and repotting. By then, the tree will have built up sufficient energy and can recover safely. However, this is the time to assess the basic structure and balance between the trunk and main branches. The distribution of main branches, bud formation, and the ratio of root base to trunk are clearly visible during dormancy. Therefore, use the winter to calmly study the tree and make plans: how are the main branches developing, where are corrections needed, and which branches can be pruned back in June or July? Those who plan ahead should already pay attention to the potential for bud formation and the distribution of flowering branches – crucial for maintaining rich, colorful flowering and healthy growth later. This way, you'll make the most of the dormant period and be prepared for the work phase in spring.
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Everything for healthy winter work

Discover our carefully selected collection of bonsai, handmade Japanese pots, substrate, wire, tools, and care products—everything to guide your trees through the winter with knowledge and peace of mind.