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We’re captivated by trees that show evidence of having survived hardship over the centuries. If they could talk, they would point to their scars, recalling the storms of life.
Bonsai designs that cultivate or include deadwood aim to create a character-filled tree in miniature form, reflecting centuries of surviving harsh environments and events. Incorporating deadwood into a bonsai is a skill that requires artistic flair and a clear grasp of botany principles.
Whether we like deadwood or not, most of us will eventually acquire Bonsai with some form of deadwood. Keeping deadwood from rotting and decomposing is crucial – nature’s natural inclination for dead organic material.
Watching a unique bonsai rot and fall apart can be depressing if deadwood makes up its most attractive feature.
I’ve been working with Bonsai for several decades, and throughout that time, I’ve learned a lot about how deadwood behaves when it’s part of a tree. The dead parts of a tree are affected by several factors.
Before we begin work on deadwood, whether it is already present or carving and producing it for the first time, these factors must be considered and understood.
Nature’s Process of Dealing with Deadwood
Dead organic matter naturally decomposes; it’s nature’s way of managing waste. Several processes contribute to this waste management system, with microorganisms being the most effective.
Plant debris naturally piles up and decomposes, increasing soil fertility by strengthening the food web.
Gardeners use this process to produce compost. Composting is a hygienic process of organic waste, creating a humus populated with billions of microorganisms that complement the soil food web.
The decomposed organic matter and microorganisms improve the soil’s health in several regards. Increased soil fertility, plant disease resilience, and aggregate formation can all be directly ascribed to microorganisms. The decay process naturally enhances the best soil features.
Managing the Natural Decay Process of Deadwood on Bonsai
Several elements contribute to the decay of deadwood. While the odds are stacked against us in fighting nature’s processes, we can preserve deadwood successfully for a very long time.
Within the Bonsai context, three main elements cause deadwood decay.
- Mechanical Decay
- Fungal Attack
Mechanical Decay of Deadwood in Bonsai
Mechanical decay is related to the effects of the contraction and expansion of deadwood over time. As a highly porous substance, wood absorbs moisture which causes the lignin to swell, and as the water evaporates, the lignin fibers shrink.
This expansion and contraction cause the lignin binding to weaken, making the wood more susceptible to fungal attack.
With time, the wood’s constant movement results in fissures, making it easier for water to seep into the wood, intensifying the effect. Despite its flexibility, wood has a low elastic limit, and the continual expansion and contraction will cause it to break down, depending on the type of wood.
Insect-related mechanical degradation is another factor. A huge variety of insects are drawn to dead wood. Examples are ants and wasps, frequently using soft, decaying wood to construct their nests.
The mechanical impact in this instance is due to external factors, the boring of holes into the wood, weakening the wood and making it further vulnerable to decay.
Fungal Decay of Deadwood in Bonsai
One of the primary decomposers of deadwood is saprophytes. Saprophytes are microorganisms that live on dead matter and break down complex molecules into simpler ones.
There is no way to prevent deadwood from becoming infected since fungi are transmitted by spores carried by air and water. Fungi spread quickly after being introduced to a new location, frequently competing with local species for food sources.
Spalting, a process where competing fungi create a wall around their area, is frequently seen as a dark black or brown line revealed after carving. The wood is then consumed by fungi, eliminating its beneficial properties and leaving powder in their wake.
A warm, humid climate makes it much easier for fungi to spread, and rotting happens much more quickly in a warm, humid summer than in a bitterly cold winter. In the context of Bonsai, deadwood in contact with the earth absorbs moisture from the soil and spends the entire day in a warm, sunny location is in serious peril.
The primary contributor to our issue, fungus-induced deadwood decay, is fortunately easy to address in short to medium term.
Fungi typically attack wood when temperatures are between 50 and 90 °F (10-32 °C). For fungi to develop, wood must be damp; the most severe rot happens when the moisture content of the wood is around 30%.
Typically, wood with a moisture level of less than 20% won’t degenerate, and any infections won’t spread. Excessively damp wood won’t decompose because the excess moisture restricts the ability of the fungus to develop by denying them access to enough air.
Deadwood Resistant to Fungal Decay
- Black locust
- White oak
- Black cherry
Deadwood Susceptible to Fungal Decay
- Silver maple
- American beech
Bonsai Deadwood Oxidization
Oxidation is the chemical process of atoms losing electrons, altering the physical properties of materials like metal and wood. There are many ways that wood might come into contact with oxygen, including rain, excessive sun exposure, and windy circumstances.
Ironically, it is this process that gives the beautiful silver-white wood the desired “weathered” look sought by bonsai enthusiasts all over the world. That said, too much of a good thing can be harmful.
Long-term preservation of deadwood from oxidation or weathering is challenging but doable.
But before we get into that, let’s look at the different deadwood used in Bonsai growing.
Bonsai Deadwood Techniques
Deadwood gives a tremendous character to Bonsai and makes it appear old and well-cared for. The commonly accepted forms of deadwood include Jin and Shari, but variations of these are incorporated to create a similar outcome.
The five forms include:
|Jin||Nature creates a ‘Jin’ when a leader or a lower branch|
|Shari||Deadwood on the Bonsai’s main trunk is known as a ‘Shari’.|
|Uro||The little indentation left from a fallen deciduous tree branch is called an ‘Uro’.|
|Sabamiki||A ‘Sabamiki’ is a hollowed or divided trunk.|
|Tanuki||‘Tanuki’ is a technique (not a recognized style) that introduces foreign deadwood into a bonsai to produce a composite.|
The Japanese word Jin (金)translates as gold. In Bonsai, Jin provides the impression of age and character. In nature, Jins are created when wind, lightning, or other issues cause a tree’s leader or a lower branch to die.
Creating a Jin requires removing the full circumference bark from a defined start point to the branch’s or leader’s end, causing the exposed wood to dry up and die.
A shorter, more pronouncedly tapered Bonsai can be produced by making a Jin from the leader in a single step. This boosts the Bonsai’s appearance of age and character as proportions better reflect older trees.
By channeling energy to lower branches by causing them to develop more quickly and contribute to an increase in trunk girth, removing the active leader reinforces the appearance of aging.
A tree with two leaders has an unattractive shape that the designer can change by converting one of them into a top Jin, which also offers an aesthetically pleasing alternative.
The Jin technique allows the bonsai gardener to reduce undesirable branches while boosting the appearance of age when applied to branches. A leftover jin may be long and curled into a lovely shape, or it may be short and resemble the lifeless fragments of a branch severed close to the stem.
Shari in Japanese translates as deadwood on the trunk. Extreme weather events, including severe snowfall, droughts, wind, lightning, and other factors, can damage a tree and cause it to sway.
The contortion of a tree is also influenced by biological deterioration, which includes animal grazing, insect infestations, and human activity.
These effects occur throughout a tree’s existence, sometimes thousands of years, as with the ancient bristlecone pines in California’s White Mountains, which are estimated to be around 6,000 years old.
If a significant component of the tree resembles old tree relics on harsh mountain terrain or driftwood on a beach, a bonsai is said to be in the sharamiki or driftwood style.
The roots and the living branches are connected by threads of living bark, while most surrounding wood is dead, without bark, and worn.
The dead wood can be shaped into striking designs to resemble severely weathered tree fragments. Regardless of the tree’s basic shape, the unique contrast between enormous dead patches and a small evidence of life is fascinating.
When applied to deciduous and broadleaf plants, Jin does not look as appropriate on coniferous Bonsai. In nature, dead branches from these species typically decay and fall off the tree.
An indentation is left where the branch formerly was, and fresh wood develops around it to create a tiny hollow. Bonsai gardeners mimic this hole as an Uro by making a small, atypically shaped incision in the trunk.
Bonsai growers frequently create an Uro after cutting a branch from a deciduous or broadleaf species to prevent an unsightly wound from scarring uncontrollably.
Sabamiki translates as a split trunk and, as a bonsai technique, creates a fracture in the trunk of your tree for aesthetic purposes.
This split, which typically runs from the base to the tip of your trunk, provides the impression that your Bonsai has been struck by lightning or has aged due to extensive trunk damage.
A deep wound is produced by removing the bark from the trunk and then drilling or cutting out the exposed wood. The hollowed section may begin halfway up the trunk or finish there, beginning at the tree’s base with a broad hole that narrows to a closure halfway up the trunk.
Tanuki bonsai is a special method (not a style) for making Bonsai appear much older. By incorporating dead wood into a bonsai, traditional styles can be reproduced.
It’s a contentious topic and is often referred to as phony Bonsai. If done well, however, it can go unnoticed. Artist Dan Robinson is credited with coining the term “Phoenix Graft” in the United States, and the reference is still used.
Tanuki is not permitted in official exhibitions. At other exhibitions, it is considered respectful to “admit to your deception.”
How To Preserve Bonsai Deadwood & Jin
Before choosing how to preserve the deadwood on our Bonsai, we must envisage our end goal and the desired color. Compared to softer wood typical of deciduous species, resinous wood typical of conifers will require a different approach.
Whether the wood is green, seasoned, old and worn, or decomposing will also need to be considered. The kind of wood and its state will dictate our method, effort required, and the product we must use.
Generally speaking, freshly carved green wood does not require preservation after the initial carving. Most products won’t adhere to the surface or penetrate the wood because it will still be damp and sticky.
Generally, it’s a good idea to let newly exposed wood weather for a year, enabling complete drying and excellent surface oxidation. There may be some fungal intrusion, but if the wood is sound and not continuously damp, this will likely have little impact.
Every year, ideally in the summer, when the wood is still somewhat dry, old seasoned wood should be treated. A fast clean with a fine-bristle brush is required before applying your selected product.
Soft, partially deteriorated wood will require meticulous cleaning before treatment. Wire brushes will be used to remove soft oxidized material in this process, either manually or with some power instrument. The wood should be cured as much as possible after completion before treatment.
As Bonsai artists, we always aim to reflect nature and character-filled trees. Incorporating deadwood into your design is one of the most effective ways to convey the exceptional resilience of trees to survive hardship.