Thread-grafting a Chishio Japanese Maple

This maple has been in training for about 8 years now. When it went to the US National Bonsai Exhibition last summer, I knew it was still early…maybe too early with regard to the green trunk and developing nebari. I also decided that after the show, I’d evaluate the tree and try to spend a few years really correcting a few flaws and improving the overall quality of the tree.

First, the nebari is radial, on one plane, and pretty flat. The tree has been repotted annually, and the roots get shortened to about a 6″ radius around the trunk. It responds by filling the pot each year. Still, some gaps remain, and I want a more buttressed base. Not necessarily a dinner plate, but better than it is now.
This is last year’s root pruning, just before filling in the soil:


This year I took it to Kathy Shaner’s workshop to work on. Here is a sequence of breaking down the root mass:








When we got it cleaned up, we identified the places to add roots and began to drill; with a very long drill bit, going in the direction we’d thread the seedlings through:

Then inserted string-trimmer line through the holes to represent where the seedlings would go. Clever, eh?


We ended up with 6 thread grafts. As I threaded them through, I scraped the “bark” of the scion, just barely exposing the cambium at the point where it touches the trunk. It should fuse on its own, but this will help things along. It’s important to do this early enough that the buds aren’t knocked off on the way through the holes. Then, cover the roots with wet paper towels along the way. This tree was bare-rooted for about 2.5 hours. A little nerve-wracking!


Here is a good shot showing most of the grafts, new roots are lighter in color. It will be exciting next spring to see how they did!


Some bamboo sticks helped pin and direct the new roots to where they needed to be. Then we gently wired the seedlings to get them pointed out and away from the eventual shade of the canopy. They need to grow quick and strong!


One more clean trimming around the edges of the root pad, and then we secured it into the pot, a little deeper to make room to cover the new grafts with a layer of soil:





Next week, more refinement above-ground!


9 thoughts on “Thread-grafting a Chishio Japanese Maple

  1. Do you mind sharing any long term plans for this tree? I’m wondering if you will eventually slow it down as it reaches the refinement you’re after; or will you continue with the patern (re-potting/root trimming) you have it in?

    • Hey Dan,
      Bud-pinching is an annual chore, or else the ramification is destroyed in a season or two. As time goes on, smaller branches will replace larger, older branches…more on in Saturday’s post. Repotting will become an every 2-3 year task, once the base is well-established. Right now, the roots are so enthusiastic, that I don’t think it could go 2 years.
      Thanks for reading!

  2. oh my god. an informative post detailing a challenging procedure done by someone with experience instead of the babblings of someone who has read a few articles yet done nothing aside from pompously demand respect for his half formed viewpoints. thank you for sharing this and your experience in bonsai.

  3. I’ve enjoyed this article as I do all your articles. I wonder if some time you could do a little tutorial about bud pinching on maples. It is confusing to me because as with most things I read I do not know if I should be doing that or something similar on a tree in training as opposed to an established tree. Things like do I pinch just the first set of leaves or continue pinching each new emerging set of leaves until until the leaves on the pad have matured. Then after we pinch the emerging buds should I let the branch grow to four or five sets of leaves before cutting it back and which to do to a tree in refinement or one in training? I have read many times over to pinch, pinch, pinch but no one tells you how many times or on what stage of development nor do they say what to do next. I would greatly appreciate you clearing that up for me.

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