When I looked into it online I saw that a lot of comercial orchards were doing Rind grafts when a certain variety wasn’t economical anymore so they’d change the variety with a Rind graft. They sure make it look easy.
My concern would be getting a late frost, but if it fails I’ll just end up planting new trees there. I’ll honestly surprise myself if it works....lol!
Once again, my experience is with persimmons not apples but I would think some of this might apply. You didn't mention the size the tree, but well established trees can support multiple bark grafts. Only one scion needs to take, but if you do 2 or 3, the chances of at least one of them taking go way up. You only keep one. If you keep two you create a bad crotch situation and the tree can split. After you are absolutely sure at least one or more has taken, you can remove all but one. With persimmons I will often leave them all summer and cull the rest in the winter. Persimmons really push water sprouts below the graft that need to be removed every week or so. The extra scions will take some of that excess energy meaning I need to remove water sprouts a little less often.
Most other types of grafts rely on cambium alignment. Bark grafting does not. I find one of the keys a successful bark graft is pressure. I like to use electrical tape. It has a little stretch to it and can provide better pressure than something like freezer tape which I use for other grafts like whip and tongue. I also like to cut the tree down at a slight angle. If you cut it square, water can pool on the wound. Even protected with grafting seal, water pooling is not a good thing. When I graft, I don't put a scion at the lowest point of that angle where water will drain into the graft. Thicker sealant is better than thin stuff like doc farwell's. It can be used but you need to be careful that more liquid like sealant does not run down into the bark grafts.
When bark grafting outdoors, the scions will be exposed to the elements. If they dry out before the graft takes they will die. To maximize the chances of success, I like to wrap them in Parafilm-M. Parafilm-M is a type of parafilm used in laboratories to seal test tubes and stuff. It is thick and sort of waxy. When you stretch it a little it becomes thinner and it sticks to itself. It breaks down and is easy for trees to push buds through it. If I have a southern exposure, I make a sun shield out of aluminum foil and tape it to the tree to shade the scion from the sun. Finally, I cable tie a bamboo stick to the tree trunk. Small birds like to light on the tallest site on the tree which will be your scions if you don't use the bamboo. They are light, but when they jump to take flight or land with any speed, it can cause enough movement to dislodge the graft before it is solid. They will tend to light on the bamboo instead. The bamboo stake also serves to train the new central leader. With a larger tree, there is so much energy in the root system the graft can really grow fast that first growing season. Until it hardens, it may tend to fall over or can break in the wind. I use cable ties to very loosely attach the new growth to the stake. It can still blow in the wind but is limited by the cable ties so it won't break. This also helps it grow straight that first season until it hardens.
Again, apples guys may want to way in on anything unique to bark grafting apples, but these techniques work very well with persimmons and I would expect they would have value to apples as well.
Thanks,
Jack
