I have several trees that were planted as bare root last year or will be planted this year, most of which will become a multi-graft tree. Peach, E plum, Asian-American Plum, E pear, A Pear, sour cherry.
When should I be considering grafting these to other varieties, if my intent is to have a handful of varieties on each one? Some of the varieties may change over time, and some may stay, but I don’t know enough to know exactly what I want at this point.
Should I be grafting what will be the main scaffolds in the first or second year? Wait until main scaffolds are established and graft at the secondary scaffold now or later? T-bud at the trunk in the 1st/2nd year or much later?
I’d select the lowest three scaffolds of a central leader pear to graft over to my varieties. Everything that grows above the grafted scaffolds will be the original variety. I won’t speculate on the others for lack of experience.
It’s easiest for me to do simple whip grafts when the rootstock is closely matched in diameter to the scion. When the rootstock is older and fatter you’d probably end up doing a cleft, or perhaps chipping or budding to it, and the larger they are the less the chance of the bud doing well. (As the diameter of the branch to which you are grafting increases the cork gets stiffer and thicker and is less friendly to the bud.)
If you t-bud or chip to the trunk, everything above that point will be your new variety, but of course you can graft to scaffolds on that as well.
Agree with Mark, as each scaffold grows older than two year growth, chip budding is not an option, so if you want to add varieties to any scaffold of the main trunk with chip buds, do it now. The longer you wait means you will need to rely on other grafting techniques that can work on thicker bark.
Most young grafted trees have a limited number so scaffolds, you can use chip budding on the main trunk to add new variety scaffolds at about an 18” vertical spacing starting with your one year old wood. As each scaffold gives you 1 year old wood you can then add new varieties to your scaffolds. Once your wood is older, should you desire to change varieties, using cleft. Whip&tongue, side, or double tongue grafts become the most viable methods on wood older than 2 years. I also find the double tongue graft very versatile once you get proficient with cutting it.