How to Treat Dead Bonsai Wood

Use a jin scalpel or a sharp grafting knife to carefully peel back the bark on the dead wood. Discard the bark.

Rub the dead wood gently in the direction of the grain with a fine-grade sandpaper if the wood appears rough. Continue sanding until the wood is smooth and polished. If the wood already appears smooth, skip this step.

Clean the dead wood with a clean, dampened toothbrush. Dip the toothbrush in plain water periodically, as needed. Allow the bonsai to dry completely before proceeding.

Wait for the ideal weather conditions to treat the bonsai wood. The wood dries more quickly on a hot day with low humidity. On a day like this, move the bonsai tree to a well-ventilated area.

Dip a small, clean paintbrush into lime sulphur. Allow the excess to drip off the brush and apply it to the dead bonsai wood. Distribute a thin layer of the lime sulphur evenly over the wood, dipping the paintbrush back into the lime sulphur as needed.

Avoid dripping any of the lime sulphur onto the soil. Soil contamination may damage or kill your tree.

Allow the lime sulphur to completely dry. Do not water the tree while the wood is still wet from the treatment.