Developing bonsai maple branches – spring work

Bonsai maple first flush in spring. (by Scott Barboza)
With spring in full swing in Texas, USA, Scott Barboza has worked on one of his maple bonsai in development again. On one of the well known bonsai forums (bonsainut) he showed how he works maples in earlier stages of development, in order to develop the branch structure of maple bonsai as much in a year as possible. With his permission, his pictures and some of his text are used in this post. He indicated that although this post deals with maples, he works most broadleaf deciduous trees in a similar fashion.

As soon as the spring flush has hardened off it is time to get to work. This is the busy time of the year for maple bonsai in development. In this picture you see the tree after the first flush. Note that he has over 50cm of growth in just the first flush! This is naturally relateed to the fact that he is located in texas, with warm springs.

Timing of work on bonsai in development

In early spring, the tree is left alone: let the spring growth to extend and harden off. Hardening means that the new growth forms a waxy cuticle. This is the point where all the stored energy used for growing the spring flush has been recovered. From this point onwards, the tree will be building reserves for next year. You can tell it’s hardened because the leaf color changes from a pale green to a dark green. When this happens it’s a perfect time to work the tree.

Objectives of spring work on maple bonsai

For spring work, he generally only works on the new growth. Unless there are side branches, he does not cut back into older wood at this time. The main objectives at this point are to:

  • Thin the number of branches leaving only those needed for the structure
  • Balance energy in the crown
  • Place the new growth to develop branches
  • Thin the leaves to let light and air into the interior growth

Thinning the branches of bonsai in development.

Maple branch ready for cutback and wire (by Scott Barboza)
Maple branch cut back and wired (by Scott Barboza)

Start by cutting off all the downward facing growth. If you have properly placed strong shoots on old wood, its OK to cut back to the new shoots. Take a look at the branch above. It was wired last year and now it has some good strong upward facing shoots that can be cut back to. By then wiring the new shoots down, movement and taper are created in the branch.

Balancing energy in Maple bonsai canopies

On broadleaf trees, we have a few tools to balance the growth. Balancing the growth on broadleaf trees means the same thing as it does on pines – we want the apical shoots to have the same vigor as the interior shoots. We want the shoots on the upper branches to have the same vigor as the shoots on the lower. The tools we have to create this balance are pruning, wiring and selective leaf removal. When I say selective leaf removal, I’m not talking about defoliation. To defoliate completely a tree like this in development will work against the speed of development. We want the strong growth to develop the branch structure and such defoliation will significantly slow the tree down. But selectively removing leaves can and should be done. Here are the techniques:

  • Prune the extending shoots. Prune the strong shoots harder than the weak ones. Leave the weakest ones alone. Let the extending shoots near the bottom of the tree stay longer than the extending shoots at the top of the tree.
  • Remove leaves. On Japanese Maples, Scott removes one leaf of each of the leaf pairs, leaving an alternating pattern of leaves. Again: Remove more on the strong shoots than the weak ones. Leave the weakest branches alone. Let more leaves remain on the bottom branches than on the strong apical growth.
  • On the strongest growth, cut the remaining leaves in half.

Wiring the young spring growth on maple bonsai

Finally, wire all the spring shoots into place. Pines and junipers have a branch structure that is often bent into place. It’s different with broadleaf hardwoods. That branch structure is grown into place. Once the wood lignifies, it becomes really difficult to put movement into the branches or adjust the angle that they exit the trunk. But these green shoots can be easily shaped with wire. Once the growth has hardened off, they can handle wiring no problem. But watch that wire like a hawk. In a few short weeks it can start to cut in and we’ll be pulling it all off again. Note that this technique was dealt with in the baby bending article.

Spring time race to develop maple bonsai

Bonsai maple thinned and wired in spring.

This is a race. You need to get in there and work the tree as soon as the growth has hardened off. The earlier in spring the better because the tree will respond by putting out another flush of growth. Depending on your location and growing season, once may be able to work the same tree 3 times each season. For trident, this can in some locations even be four more times. As the branches get further along, it gets less wiring intensive. But for now, we’ll forge ahead until we get the basic branch structure developed.

Tell me what you think!