Two Chinese Hackberry Bonsai get an Autumn Cut

In my previous series on what one should and should not be doing on your bonsai, one of the suggestions were that once the leaves of your deciduous trees begin changing that it is a good idea to get some final work in for the season.

This post is about the last work I will do on two Chinese Hackberry which I field grew from seed and am in the process of training as bonsai.

I hope the images and accompanying text are helpful and descriptive enough that you can follow the process.

First things first

• What species can I do this with? All deciduous trees but especially those which bleed a lot if pruned in spring for example maples.
• What techniques or work can I do now? Wiring is best done a little earlier than when the leaves begin to change colour but can still be done now. Pruning, especially branches and twigs or more refined trees (although sacrifice branches on trees being developed should be pruned in late spring or early summer preferably).
• When do I do this work? The time to do this work is when the leaves of your tree have begun to change colour.
• How do I deal with the leaves? Cut them off using defoliating shears or trimming scissors, or if you can strip them off so the structure of the tree is revealed and you can work confidently.
• What happens if I wait too long? If you waited too long and the leaves have all already fallen off naturally, sap flow would be virtually nil and any cuts you make will not begin healing and any wiring you did will have little time to take advantage of the growth the tree puts on at this time.

Hackberry #1

With this tree, I sort of headed off in a certain direction with its styling but then changed my idea of what I want this tree to look like. Initially it was being styled in a very stylized tree form with clearly defined foliage pads, much like that of a formal upright pine. The final look which I would like to attain is more befitting a deciduous tree and will have a fuller canopy, although made up of individual branches.

Image caption. The front view before and after pruning and wiring

The tree was repotted at the beginning of the season and since then it was just allowed to grow freely. This means that there were some branches which became quite strong and some which were left quite weak as they were slightly shaded. I did not wish to defoliate the tree though as the procedure weakens the tree proportionate to the number of leaves removed or alternatively reduce cut to reduce size. In the season to come I will balance the energy through partial defoliation.

There is an imaginary outline or silhouette to the tree towards which I am working. Branches which exceed from this rounded triangular shape are pruned back. As the branches near the outline they must be developed slowly so as to keep them as delicate as possible. 

The apex of the tree is the easiest growth area of the tree to develop as this part of the tree is also the strongest. The problem I have is the lower areas, particularly lower left and between the first branch and the one above it. There are voids in these areas and I am attempting to graft branches, using these methods.

Image caption. Side view before and after work.

You can see from this side that the entire tree leans slightly forward. Be careful that you do not make this angle too far forward though or you will have problems with shaping the canopy as of course all growth needs its portion of sunlight so you need to keep each successive branch longer than the one above it or it will forever be weak and even potentially weaken to the point of death.

Image caption. Rear view before and after.

Image caption. Left view of the tree before and after work

Image caption. Bird's eye view of the tree from above

It's very helpful to check the canopy from above to look for any branches or any areas which are causing the overall shape of the tree to break from the imaginary outline. The outline in most cases with informal upright styled trees is going to be oval. 

Image caption. Branch structureof the first and main branch

Branches should not resemble the backbone of a fish, so called "herringbone" branches. Rather there should be a main branch shooting out from the trunk which then splits repeatedly, each time getting thinner and thinner. This tapering in the branches creates visual interest. Movement must however not only be visible from the top but very importantly from the front too.

Once again, shape the branch to an overall fan shape but also bear in mind the imaginary outline of the tree canopy and ensure the branch follows it.

Image caption. Main branch as seen from the front

Although its cool to look at your carefully designed branches from the top, don't forget that we view our trees from the chosen front. This means that you need to create volume in your branches. You do this through layering the branches above one another. However try not to create a situation where a branch will be directly overhead another, or the top branch will take all the sunlight and energy away from the lower branch, which will weaken and eventually die back if you're not carefully. 

Image caption. Wiring technique needs to be practiced.

Wiring is a basic technique which needs to be practiced. If you cannot master to some extent this basic technique then you are going to be very frustrated with bonsai as wiring is a fundamental technique in the Japanese form of bonsai. Here are a few basic wiring tips in video format I will share with you.

Wire using the correct thickness. Not too thin it will not hold the position. Gaps between branches being wired and the wire applied to it can result in snapping as you are forced to "over bend." Too thick and you damage the bark of the branch when applying the wire. Try to limit the number of strands running parallel to two at most, more and your tree quickly resembles wire trees and not wired trees. 

When you want to place a curve in a branch then try to place the wire on the outside of the bend so that it can support the bend. Experiment with this suggestion. Try wiring a branch with wire on the inside and another on the outside of the area where you want to make a bend. Now bend these branches and see how much further you can bend the one where the wire supports the bend without incurring any cracking.

Image caption. The apex, which still needs work

In the apex branches branches will lean towards the vertical. As you move down the tree the branches will tend from the vertical to the horizontal or below if you are creating an image of a mature tree.

Image caption. Approach grafted branch

I did this approach graft earlier this season. It has not fused well and I cannot see any signs of thickening of the graft. I will therefore have to give it at least another season before I decide whether I need to repeat the process. Hopefully it will fuse and I will have grafted a branch where I need it.

Image caption. Old field growing scars

Scars such as this are either going to take very long to heal or will never heal, especially if the wood has rotten. In this case the best would be to remove the rotted wood, score the edge of the bark to expose the cambium and then seal. Doing this repeatedly will stimulate healing.

Hackberry #2

Image caption. Front view of the tree after work

Although this tree also grown from seed as with the first tree in this post, is developing well, and the vision I had for it is beginning to materialize the main branch is still almost non-existent. The branches which have not been cut are being developed as the main branch. At the moment the base of the branch is too thin so I am growing these branches long and without ever cutting their growing tip, so they continue to extent. Eventually the base will become thick enough and I will be able to cut the branch/es back.

Image caption. Healing over a large scar

Another added benefit of developing the main branch is that the scar immediately below it is also healing over quicker due to the increase sap flow around it. I filled the original hole earlier this season and detailed the process in this blog post.

Image caption. Front branches

When I was taught how to style bonsai trees, I was told that I should not have any branches coming towards me in the lower part of the tree. However imagine my surprise when I visited several famous Japanese shohin nurseries and saw their extensive use of branches in this position. They certainly can add a lot of volume to the tree, especially if they are to be displayed in winter when there are no leaves to hide behind.

So use frontal branches, just don't forget to give them some interest by putting bends in the branches.

Image caption. Ramification takes time

Ramification is something that we bonsai artists strive for. When we are unable to achieve good ramification we blame it on the environment we live in, we blame it on the fertilizers that are or are not available or some other excuse. The fact is that ramification takes time (correct technique, growing medium and many other factors) and should not be rushed. If its rushed you will see this as the twigs will be coarse and thick, further back you will also see knuckles (especially on species such as Chinese maples) where the artist has repeatedly cut branches back to as a result of incorrect use of fertilizer which led to excessively long internodes.

In the beginning ramification is a slow process, but each time the branch divides you have an exponentially larger number of branches, which can rapidly fill the canopy and give you the dense appearance which is so impressive when the tree is without leaves. Of course then the challenge becomes keeping this fine network of twigs alive without sacrificing the health of the tree but that's a subject for a future blog.