Deadwood Techniques in Bonsai Growing
Parts of a tree or branch can die due to multiple reasons, such as extremes of weather, lightning, branch die-back, pest infestation, disease and so on. Bark on the dead area decays and heartwood of the tree gets exposed. Over time, the exposed wood turns white giving it an appearance of withered driftwood found on seashores. This in bonsai parlance is called “deadwood”.
One of the notable techniques employed by bonsai practitioners for giving an aged mature look for the bonsais is creating deadwood. Deadwood also gives allows the bonsai artist to remove unwanted branches or mask damages to the trunk, and convert them into deadwood that add to the beauty and age of the plant.
Powered tools, such as small rotary tools, are generally used for creating and shaping deadwood, as the stress may be high on the tree with manual shaping. After creating deadwood, the exposed area is treated with a bleaching preservative, such as Lime Sulphur. The preservative protects deadwood from rot and pest infestation, and gives a weathered, aged look.
Various types of deadwoods created on bonsias are described below.
Jin: Jin is the deadwood on branches or on top (apex) of the tree. Jin gets created in nature when wind, lightning, or some other calamity kills a branch or tree top. For creating jin, bark from a given point till end of the branch is stripped off. If the jin is on top, bark on the branches forming apex is removed. The wood is then shaped to give an appearance as if it has been sheared off by some natural force. In addition to the weathered look, top jin can give a more tapered look for the bonsai, which creates an illusion of more age.
Shari: Shari is deadwood on the main trunk of the bonsai. Natural causes of shari include trunk damage from an external source, lightning damage, or a falling branch that has ripped off bark from the trunk below it. Shari, usually shallow, runs vertically on or around the front of the trunk and exposes a dead portion of the trunk surrounded by living bark.
Sharimiki: Sharimiki is when a large portion of the trunk is dead and has weathered driftwood. Branches get connected to the root through veins of living bark, but large amounts of the surrounding wood are free of bark and dead. The deadwood may be carved into arresting shapes, to look like severely weather-beaten tree remnants. Sharimiki driftwood trees often do not follow conventional bonsai styles, but the arresting combination of large dead areas contrasting with small signs of life is compelling regardless of the shape of the tree.
Sabamiki: Sabamiki means hollowed trunk or split trunk. It gives the visual effect of a lightning strike or other severe and deep trunk damage, which has been weathered over time. Sabamiki is done by stripping bark from the trunk, then drilling or carving out the exposed wood to produce a deep wound. The hollowed area may start and end partway up the trunk, or it may start with a wide opening at the base of the tree that tapers to closure partway up the trunk. While creating sabamiki, care should be taken to see that it does not interrupt the flow of nutrients upward or sideways to the rest of the tree, or else the branches after it will die.
Uro: In some tree species, dead branches rot and fall off the tree. An indentation is left where the branch used to be, and new wood grows around it forming a hollow. This is called “Uro”. Uros are generally formed close to the bottom of the trunk. This natural phenomenon is replicated by making a small, irregularly-shaped hollow in the trunk of the bonsai. Uro can be gainfully used to hide or cover up an ugly scar formed by earlier branch removal.
Procedure for applying Lime Sulphur
Before applying Lime Sulphur, protect the soil by putting a cloth around the plant to prevent the Lime Sulphur from falling/leaching into the soil. It may be harmful if absorbed through the roots. It can be applied on the exposed wood, both live or dead wood. In my experience Lime Sulphur is not harmful if applied on live wood. As the viscosity of Lime Sulphur is low, there is a tendency that it runs down the plant, when applied, into the soil. In order to prevent this, it may be a good idea to wet the surface lightly with a sprayer before applying Lime Sulphur.
After applying Lime Sulphur, leave the plant in the sun. After about two weeks, repeat the process. Thereafter apply Lime Sulphur every year.