I have taken purchased trees of a variety on a rootstock and made them into multigrafted trees.
If I wanted to start one from “scratch” - say an apple, starting with a rootstock, what’s the best approach of the options below?
Say I wanted a 4-in-1 apple on Bud 9. Typically I’d prune this into an open center so each variety is more “equal”. vs a central leader where the “top” piece would dominate over time.
Let the Bud9 rootstock itself grow to some size and grow some scaffolds on it, then select the four best scaffolds and graft your desired varieties to the scaffolds (therefore an open-center shape).
Graft one of the four varieties on the Bud9 like you would any other, then when that variety branches, graft the three other varieties onto three of the scaffolds and leaving a fourth of the variety originally grafted.
Bud 9 is a very dwarfing root stock. It’s not the best choice when it comes to multi trees. That aside to get scaffolds you’re going to just need to regularly head the central leader to encourage branching once it reached a moderate height.
Retail multigrafts are done with bud grafting. Thats done late summer with activly growing trees and bud wood.
The tree that seemed to work best for me had four main scaffolds. I grafted a variety to three of them and left one branch untouched when it was a fairly young tree My Frankentrees are fun but in the end seem random. I have gone totally off the rails and grafted 10 or 20 to my biggest trees on M111.
The more controlled approach made the most sense. I purchase a 4 in 1 Asian pear from Starke once and that’s how they did it. Now I would just make my own and save the extra money that I would pay someone else to graft a tree. And it’s more fun to boot!