Shohin trees are those that are in the range about 3″ tall to about 8″ tall. While there are multiple size classification systems, the Nippon Bonsai Association recognizes that Shohin are trees up to 20 cm, which converts to about 8″ for us Americans. It is also commonly accepted that the tree not be too wide – up to 10″ wide is common, varying slightly by style.
There is no right answer to what a shohin bonsai should look like. Just like any bonsai, shohin are created in different styles, with differing trunk sizes and to differing degrees of ramification. If you take the time to visit bonsai shows after a while you will find that there is a general range starting from trees that are not proportionally much more than a sapling with a few branches up to the fatter trees in some American shows and in Kokufu. So, what is the standard of quality and/or most desirable characteristics in a shohin? While that depends on the taste of the individual, there are certainly some ways to differentiate between trees that are more easily created and ones that are more difficult.
Trunk growth and training considerations
There are a few special considerations for trunk creation in shohin. When designing a shohin take into account that the size of the space taken up by the trunk needs to be less than six vertical inches because the apex of the tree will need enough vertical space to create good ramification. The curves that you create should be smaller and tighter than curves that you would create for a larger tree. The curves used for a shohin would fill in and potentially cause reverse taper in a larger composition while the curves for a larger tree would mostly be outside the scale of the composition in a shohin.
Sacrifice branches are the primary method for most species to increase the size and taper of the trunk during the growing stage. The placement of the sacrifice branches should be carefully considered when the tree is very young. The primary sacrifice branch would typically be set after the second year’s growth on a pine, or in the first year on a maple. Angle the sacrifice branch to the back or side of the tree and add movement to the part of the trunk that will be kept to create the desired style. A second sacrifice branch can be added in subsequent years, however the spacing of the sacrifice should be quite close so that the taper is more abrupt since we only have 6″ to work with. In a pine, decandling of the small side branches that will make up the next trunk section can shorten the nodes and force more side branching. Select the second sacrifice branch to be toward the back above the next small section of the trunk.
Special Branch considerations
While medium and large trees may frequently have a length of the primary branch that has no side branching prior to splitting and starting to ramify, in a shohin there is not really much room for this. The space should be eliminated such that the first side branches are no more than 1/2″-1″ from the trunk. In a Trident maple the nodes can be quite long on side branches initially. After the branch elongates somewhat, small buds typically appear near the base of the branch and grow much more slowly. Allow these to grow for a while before you eliminate the original branch. The new branch will have shorter nodes and can replace the old one. A similar process can be used on Japanese maple and on black pine typically.
Defoliation of maples is a commonly used technique on all size trees but is particularly important for shohin trident maple bonsai. The reaction that the tree has to defoliation is to issue new growth more evenly than if the tree is simply pruned. Used with caution and attention to the health of the plant this technique will greatly increase ramification and shorten node length. Tridents have the good and bad trait of issuing many buds from a single point near the base of a branch. This is generally not desirable because it can cause swelling and reverse taper in the trunk. However, if a point is carefully selected right above a chop point it can simultaneously act as a catalyst for healing and a place where you can have many branches close together, similar to a broom style. Do not use multiple bud points on opposite sides of a cut as this will cause reverse taper.
Grafting of branches may be necessary to create a high quality tree. Identify areas where a branch is needed and remedy. In pines this is relatively easily accomplished by scion grafts on young trees; junipers can be scion grafted with good success as well. Tridents and Japanese maples are commonly thread-grafted to add branches, place the entry point under another branch so that the wound will be less noticeable and will heal more quickly.
Pine needle buds – Summer decandling on Japanese Black and Japanese Red pines is typically performed by removing all the new growth, leaving the winter node point in place. This causes a reliable reaction that will shorten the branching and increase the ramification and back-budding. But, the length of the new growth is still added to the length of the original branch. Even with diligent control of summer fertilization this technique can lead to branches that are beyond the desired silhouette of a shohin pine in only a couple years. Instead, leave a few of the old needles intact along the top of the branches as they grow out from the trunk the first and second year. When the branch is strong enough to decandle, decandle the entire tree, or just the stronger top sections; make the cut points behind the node points to induce needle budding. This will shorten the bare space from the prior year and increase ramification without increasing the size of the tree. The reaction to this technique is slower than to the standard technique and it is also less reliable. Do not use this technique unless the tree is very healthy; best results are obtained when the tree is exhibiting uncontrollable growth after the normal decandling procedure.
Root and Nebari considerations
The nebari and trunk flare near the soil line may add slightly to the height of the tree so space should be left in the vertical allotment for development of the nebari, it can enhance the flare and visual flow of the composition greatly when done correctly. Shohin trees are shown off to greatest effect in very small containers; they need to be able to fit into a small and shallow show container while still allowing some room for root growth. Because of this, large roots projecting outward from the trunk should be cut off primarily during the growing phase, but also as needed during refinement phases. The visible roots in the nebari that remain should be trained in an outward and downward fashion rather than straight out so that they can more easily be pruned to reduce the depth and width of the rootball. It is a good idea to plan for some of the height and flare of the trunk to be composed of fused roots at the base. In a pine this will happen around year 9-10 given the right size and distribution of roots.
The functional part of the rootball should be carefully trained with care equal to the details in the branching. Using a larger container for growing purposes is not only common, but almost a necessity for many trees. The tree can be transplanted into the show container a month or two before the show and then removed afterward to live again happily in a growing container with an extra inch or two of space both vertically and horizontally for the majority of the year.
For the author, flowing trunks, rather than more static informal uprights in the shohin size typically lead to more interesting compositions. Growing the trunk is faster than an informal upright and the basal flare can often be created by utilizing the nebari.