Best time to truck chop Japanese Maple?

I have a follow-up question to: https://bonsaitonight.com/2016/04/22/japanese-maple-bonsai-working-from-a-sub-optimal-starting-point/.

I’m still wondering when is the right time to truck chop a Japanese maple. Joan’s comment suggested early spring, giving a chance for the tree to recover. However, not sure I fully understand why.

If in early spring I assume it’s after bugs swell, this means all the energy stored in the tree already went up to the upper portion of the tree (trunk and branches) so none are left in the roots.

If we trunk chop now, how will the tree have energy to recover? I’m assuming here most of the energy is stored in the roots (which I’m not sure it’s true). So, it might be better to trunk chop in late winter, before the tree starts pushing the stored energy up. There must be science that can explain it - but not sure how to find that. Thoughts?

Specifically, I have a grafted one with a great base but I want to start over as the graft is bad. This will be a very low chop so I’m nervous…

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That’s an interesting project. It’s usually best to make the cut a bit higher to leave room for new branches to emerge at different levels but because the graft is low, there’s not a lot of room for maneuvering.

One option would be thread graft a new apex and possibly branches before making the cut. That way you can take advantage of the best roots (they look good in the photo).

As for the timing of big cuts, my only thought is that the tree can begin to callus immediately or it can wait before getting started.

When we make big cuts in fall or winter, the tree may not be active enough to begin healing right away. If I cut in early spring, the tree will be active and can begin callusing immediately.

I haven’t carefully studied this, but I have observed that the ends of big cuts can dry out and die back in fall or winter. Cutting during the growing season seems to minimize this.