While many amazing examples of juniper bonsai are created from trees collected from the wild, smaller trees of exceptional quality can be created by careful crafting of juniper cuttings over as little as 5-10 years.
When thinking about creating a juniper bonsai we must consider the interesting characteristics of the species. Desirable juniper characteristics in bonsai are generally ones that imitate old wild junipers growing in the mountains:
- Trunk has good movement including twists and curves
- One or more lifelines are prominent on the front of the tree
- Deadwood is aged, irregular, natural-looking and with interesting shape.
- Some irregularity in the branching
- Cross-section of trunk is not round, ideally it’s ribbon-shaped or fluted.
The natural tendency of the Kishu cuttings that we work with to create yamadori-style trees is to grow a circular cross-section with many large ascending branches. Left alone, under good growing conditions such as in a yard or a large container the young plant will become a large bush with no deadwood on the trunk. Interior branches will become weak and eventually die if the tree is not trained. This will leave us with inferior stock for bonsai. It is up to the bonsai artist to create a pleasing composition.
The general procedure for creating a yamadori-style tree is to start with a young plant with a flexible trunk. Nursery material in 4″ liners up to 1-gallon can is usually suitable. From a cutting under good growing conditions Kishu can achieve 8-10 inches of height in a couple years, removing larger side branches can encourage the tree to gain height more quickly. Once the trunk is large enough to work with, but before it becomes too stiff, training should begin. Older cuttings that have grown slowly will be more stiff and more difficult to train with tight turns.
Wire the whip, using wire large enough to bend the lowest section of the trunk. The wire should be applied normally – anchor at the base by pushing the end of the wire into the soil at least a couple inches. The normal 45 degree spiral will work but a spiral with closer loops will allow for slightly more control. Alternately, two spiraled wires, spaced evenly apart on the trunk can provide even more control. Use a smaller piece of wire for the smaller upper portion of the trunk, splicing it beneath the larger wire to anchor properly. Bend and twist the tree into a pleasing shape, twist should be made in the direction that makes the wire tighten against the tree, the wire will become too loose if you twist it in the opposite direction.
Wiring a whip to create a yamadori juniper. [a] The whip is wired with a tight spiral, remove large branches to create a single trunk line. [b] Bend the trunk into a pleasing shape. This will typically make the tree a lot shorter. [c] After a few years of trunk fattening the large sacrifices are removed and small branches are trained to create the bonsai crown and branching.
The consideration of the eventual shape of the trunk is likely the most important aspect of the process. Despite it being part of the goal of the growing regimen, it is easy to forget that the trunk will change over time, sometimes to our advantage but also sometimes disastrously. The yamadori style creates an illusion of mass by placing portions of the tree that already exist low to the ground, thus visually anchoring the composition in a fashion similar to that of a tree with good nebari. A tree with only a 1/8″ trunk can quickly appear similar to a tree with a 1″ trunk through careful bending. Consider the visual mass that you are creating at different heights as you bend the trunk and taper the visual mass the way that you want the trunk to eventually taper.
Trunk shape considerations. When making bends in young stock it is important to think about how time will affect the composition. [a] No bends at the base followed by tight bends will result in the appearance of reverse-taper as the tree fattens. [b] Keeping tight curves near the soil line can result in additional apparent girth in a short time. [c] Only small movement in the trunk can be repetitive and uninteresting. [d] Only gross movement in the trunk can be too simplistic, however over time can be improved (see [g]) [e] The first section of the trunk should not be vertical. [f] Severe bends higher in the tree can result in the tree looking unstable due to the visual mass being too high. [g] Careful application of technique can result in simple shapes that are more pleasing than more complex ones.
Six to twelve months after the tree is bent remove the wire. Allow some branches to grow wild for a few years to fatten the trunk. At the same time maintain some small branches and wire them with good movement to be part of the finished tree. Remove weak growth from the bottoms of branches and thin once per year to allow more light to the interior as the size of the plant increases.
Here are a few tips and tricks that will make your yamadori-style composition more interesting in the long run:
- The bends in the trunk should have both small and gross movement, the small movement within the flow of the larger movement.
- Before bending, consider stripping the bark from one entire side of the young trunk, then add some twists while bending.
- Using young Kishu, live sections of the trunk that are in contact with the ground will eventually issue new roots which opens up interesting possibilities (see Figure 3).
- Where the trunk exits the soil it must not be vertical; do not allow even a small straight section.
- Remove branches that get pinched in the middle of bends and twists.
- Each winter remove some sections of bark or kill a couple branches to add more character to the tree as it ages. Successive removal of bark on the trunk will add a lot of interest. (see Figure 4).
- Trees that will be small should have tighter movement in the curves while trees that you want to be larger can have looser curves.
Figure 3. Roots will issue from some juniper trunk sections in contact with the soil. A looping bend where the trunk contacts the soil can give an appearance of girth that is much greater than the actual girth of the trunk. As the trunk enlarges the spaces between the loop will decrease; caution should be used as lifelines that press against each other can girdle themselves over time, direct the important lifelines away from firm contact.
The initial creation of the tree’s shape through bending and twisting is only the first step in the creation of our evolving composition. After removal of the wire carefully examine the structure of the plant. The trunk will have a mostly-round cross-section; however, an irregular cross-section is more desirable. Remove small sections of bark successively or strips of bark to separate the trunk into separate lifelines. If you twisted the tree during the initial wiring you will be able to pull a strip of bark starting near the base or top and it will peel off a line that follows the twists and turns that you added. A series of bark removals can be performed over a few years to create a ribbon-shape in the trunk. Use a similar technique on the sacrifice branches so that when they are eventually turned into jin that the cross section is not round.
Figure 4. Cross-section progression of a juniper, the figure assumes good growth of the branches to stimulate wood production and speed the process, under bonsai training the progression would take many-many years. From left to right: [1] A young juniper typically has a round trunk, this is normal for most nursery-grown specimens; the bark covers the entire circumference of the tree. [2a] A section of bark is removed on one side to start the tree on the path to a more interesting shape. [2b] Most of the bark remains. [3] After a year or more of vigorous growth the tree has produced more wood all around the sections that are still alive. The lifeline does not easily roll-over the dead section but expands in a circular fashion. [4a] After another year or more the lifeline continues expansion while [4b] another section of bark is removed to separate the lifeline into two separate lifelines. [5a] Additional bark is removed to encourage the ribbon-shape of the trunk [5b] Care should be taken to keep both lifelines healthy: pay attention to both branch growth and root health. [6] As the tree continues to grow the ribbon shape starts to be more prominent, successive removal of small strips of bark creates texture in the deadwood [7] After 7-10 years the ribbon shape can be achieved.
If you were unable to add a twist to the trunk during the initial styling you can carefully add additional twists.
Adding a twist to a section that originally had no twist. [a] Start on a trunk section that is too straight and/or would benefit from adding a twist. Cut small strips of the bark out in a spiral fashion. The strips should cut across the grain of the lifeline but only in small sections. You are establishing the lower edge of the lifeline by redirecting the sap flow to the side of the small sections. Do not allow the tree to callous over these small windows. [b] Keep an eye on the trunk over a year and successively remove small sections of the bark. If the tree is growing slowly it will take longer. [c] After the line is established remove a larger portion of the lifeline below the line. [d] As the lifeline swells it will change the shape of the trunk and widen slowly, additional sections can be removed as it enlarges.
The branches that will make up the canopy of the finished bonsai should be carefully maintained as healthy and short during the period of years when the trunk is being created. Once the sacrifice branches are removed wire the small branches to add smaller movement and create the finished crown. Typically the branches descend largely from the top around the twisting wood, as is the case with many of the wild junipers that are our inspiration.
