Branch Flattening for Light Optimization and Taper Control in Juniper Stock

Posted by on Oct 25, 2020 | 3 Comments
Branch Flattening for Light Optimization and Taper Control in Juniper Stock

Refinement and stock growing are often two entirely separate parts of the bonsai process. Whenever we are working on plants from a young age the aim is to create the best tree possible in the shortest possible time. If you find the opportunity to combine parts of the trunk growing or “building” stage of growing with the refinement stage you will be shaving years off your process.

I’ve been working with Kishu juniper for more than 15 years now, initially just with a couple trees that I was developing from whips, and more recently with larger batches of cuttings and a few trees that have been field grown. In 2013 I took a batch of cuttings that I’ve previously mentioned in a post about wiring small whips for making mini bonsai. From that same year I’ve also been developing a handful of cuttings into larger trees (not large, just larger.) These trees have proven to be an interesting challenge for a number of reasons, and in addressing those challenges I have managed to incorporate some techniques that shave a lot of time.

I don’t find raw field-grown trees to be particularly interesting because in many (perhaps all) cases the branches that come off the trunks are not usable. Sizing is one issue with branches and taper and movement are the other. First, examine the natural pattern of these field-growing junipers, noting the ascending vigorous branches that are lateral and diffused. Unlike the straight upright growth of a pine tree, this lateral pattern occurs naturally in shimpaku, kishu and itoigawa juniper growth. There is not a lot of coaxing needed to get the plants to look like this.

In smaller stock growing in containers we see the same pattern frequently created when the trees are vigorous and left to grow. The tree below, which has had significant training and previous wiring, has a shoot that is ascending laterally at about a 45 degree angle which is the most vigorous part of the plant. This shoot is responsible for a good portion of the wood production in the trunk.

A third example from a piece of material that was field-grown and is now in container training below illustrates how left to grow, the long shoots will abandon the interior growth in favor of the vigorous outer growth as we would expect.  The lower and interior growth is not receiving as much light and is also being inhibited by the hormone production of the strong tips at the end of the adjacent shoot. The result is that there is almost no usable foliage within the first 6 inches of the shoot, which would ideally be where we want all the foliage we will use in the final composition.

This tree was cut back heavily to remove many extraneous branches and foliage a little over a year ago. In the last year the result has been that many of the small weak shoots that were previously shaded and lower have gained vigor.  However shoots like this are not ideal because it will take an extra number of years to grow them to the size needed to create the rest of the tree.  Ideally, we would have saved these years by doing some work to the tree while it was in the ground and growing vigorously.

Two Techniques

In the batch of trees in containers that I have been working with, regular thinning and wiring has allowed for the shorter growth needed for the final designs to remain healthy and compact. In managing that growth I have tried a couple different techniques to try to simultaneously build structure and avoid compromising refinement; one technique seems to be clearly superior to the other, but both have their place and can provide benefits.

Wiring And Folding/Twisting over

Initially I imagined that using wire to both introduce tighter movement and doubling the branching back on itself while twisting might create superior material by both exposing the basal lateral foliage to more light and inhibiting the tip hormone production.  The results are interesting, but there are a couple problems with this technique.

Problem 1: Bending the vigorous shoots over eventually causes a bit of a scrum because of wood production, and this can eventually lead to fusing and masses of wood that appear to be reverse taper. The issue is really that we are still enabling the tree to concentrate on this one branch by bending it over the top of the other branches.
Problem 2: Shading from the shoots that are doubled back over the composition weakens smaller interior and lower shoots, eventually moving all the foliage higher up the trunk/tree and increasing the composition height.  While there are techniques that you can use to move foliage back down and create a lower crown, you are creating a longer trunk line, and you may be obscuring already well-formed curves.  In the photo below, you can see the amount of shading on the lower trunk created by the branch that has been bent back over the top.

Wiring and Twisting/Flattening Outward

After twisting and folding over a bunch of trees I eventually realized that twisting and folding branches outward might provide a superior result in many scenarios. The key differences are:

1. Moving the vigorous shoots outward removes shading problems from the interior smaller growth.

2. Flattening the branching encourages the interior growth to gain vigor as hormone production at the tip is reduced.

3. The large shoots are lower on the trunk rather than increasing the height and wood bulk higher in the composition.

4. The small central/top shoots eventually gain size but can be cut back and controlled continuously.

In the photo below you can see that two large and a third medium branch have been bent outward, both mimicking the natural vase shaped growth pattern and providing ample sunlight to the small central growth that will eventually be the finished tree.

In the example of the field grown tree the vigorous shoots at the top left were formed during field growing. They are not currently shading the smaller shoots, but the length is excessive.

The solution is to bend down all the vigorous shoots while allowing the side branching on those shoots and the weaker growth from the basal buds to run.  While this is by no means a satisfying final result, these couple wires bring us an important step closer to a good final composition.

As mentioned, both techniques have merit and can provide benefits, so the key is to know when to use one and when to use the other.

My suggestions are as follows:

Folding Over: use this technique when you want to create an extension to the trunk and for smaller growth near the apex. Be cautious about the amount of space you are leaving between the turns as this space can close up over time. Consider removing the bark and cambium from the insides of the curves to avoid the tree closing the gap over time.

Flattening outward: use this technique to reduce the vigor of individual shoots while keeping them on the tree to drive wood production. Wire and twist to introduce movement to what will eventually be a jin. Then remove side branching on the shoots to a few inches beyond the smaller branching that may eventually be part of the finished composition.

I believe these techniques, while demonstrated here on Kishu alone, are applicable to many different juniper species. For a bit of interesting confirmation, check out the photos from Kazuo Musume on Instagram.

I invite you to leave your comments below with additional tips and techniques you find useful in relation to these.

3 Comments

  1. Steven Warburton
    October 26, 2020

    Hey Eric! This was a well timed article as I’ve been working on a few junipers this fall. Starting to get closer to understanding what branches and foliage are important for the final design versus unusably thick or as you pointed out far away from the trunk line. Seems like most nursery stock presents this type of challenge and you’ve given some tips on how to overcome that. I wish more pre bonsai material treated in the ways you suggest existed out in the market! Would make the transition from mostly raw stock to finished all the faster. Appreciate the work and research you put in to this one!

  2. Joe Gutierrez
    October 31, 2020

    Very interesting and informative !
    Thank you …