I use RootBuilder (and RootMaker), design and principles by Dr. Carl Whitcomb. I grow tropicals in a greenhouse, we're talking 100 gal. Rootbuilder pots that use so much soil I mix it from bulk using my tractor. Principle is to induce lateral root output up to 4" behind the terminated root tip, then upcan (or add more panels whatever the case may be). You're trying to create a very fibrous, highly efficient/effective root system. Accordingly, pot size will be smaller with less inputs required. Get Whitcomb's DVD. It's excellent albeit too damn long, like 2 hours. For tech info talk to their employee Wayne.
I've used copper hydroxide paint on just about every kind of plant material out there including cannabis, veggies, fruit trees, evergreens. It is more effective than products that use air and light to root prune.
https://www.rollitup.org/t/spin-out-for-chemical-root-pruning.9114/
Another great product is TreePots from Stuewe. Tall one sitting next to a RootBuilder. I'll post some pix of just a few things I've used for about 20 years or so which includes RootBuilder, from a 100' roll.
Adding panels, expanding pot. Notice thick roots penetrating native soil.
Copper hydroxide paint:
Stuewe treepot with future rootstock by RootBuilder pot:
Uncle Ben