Benefits of Larger Root System?

[dbonsaiw]

I spent this season growing out a few Japanese maple trees and their roots, with trunk chops in mind for them next year. My thinking is that having a massive root system will cause a large imbalance between the roots and foliage when I trunk chop and thereby better ensure massive backbudding. For example, I have a JM that must be over 7 feet by now, with trunk approaching 2 inches. It's in a 6 gallon pot. I plan to chop down to about a foot or so (to the lowest current branches) in early spring 2023.

I also have a smaller JM growing in an 18"X"12"X2.5" box (a bit shallower than I wanted in retrospect) that I repotted this year. I'd like to try what Merrigoli calls the "mighty trunk" on this one and have been working the trunk down to get lower branches (I was too fearful of dieback to just prune the trunk down to the nebari in one go). The plan is to prune this as far back as possible in the spring and finally start growing the tree. I figured that not repotting next year would give the tree the same imbalance thereby causing tremendous growth lower down and growth of the trunk.

So do you leave a large root system to power growth or just prune the roots at the same time? I am weighing the pros and cons of repotting vs. not repotting.

I did not have the greatest of luck with blind trunk chops this year and figured the trees were just too weak to perform properly. So I thought I'd improve my chances next year by equipping the trees with large root systems before I take the saws to them.

 

[ShadyStump]

Bumping back to page 1.

I also am curious here.
There's allot of talk about the balance between top growth and bottom growth, but what this looks like seems to be very species specific.
It seems to me that maples should behave just like you're thinking, but I'd like someone who actually has experience with maples to confirm.

 

[Leo in N E Illinois]

@dbonsaiw - You have the principal right. In theory. Big root system, low chop, should explode with back buds. I had several maples from 1980 through 2005, then lost them during a health issue. I really regret the loss of my Arakawa. Of course with Arakawa, once you have a trunk, no more "trunk chops" as the whole point is bark. I never tried to create a "sumo" trunk, fat wide nebari with just a short volcano of foliage, that style is popular with azalea these days.