I’ve had better success in grafting peaches over the years, but I still prefer to fall bud them (T-bud). It’s faster for me, and success is still better.
For spring grafting, many people have issues of dormant peach wood budding out in the fridge, as Alan mentioned. I solved that problem by using a dorm fridge and set it so that it freezes the wood right at 32F. Then about once a month I take the wood out of the fridge and let it defrost at room temperature, then put it right back in the fridge. That seems to help keep the wood from drying out (i.e. freezer burn). Be aware that some newer dorm fridges won’t get cold enough to freeze the wood. The older (mechanical thermostat) ones seem to have the flexibility to set them cold enough to freeze the wood.
A common mistake new grafters make is they try to graft peaches at the same temps as apples and pears. A common piece of advice is that apples can be grafted when new leaves are about the size of mouse ears. But for good success, peaches generally take much warmer temps when apples have mouse ear leaves. I prefer the next week to be high 70s or low 80s for the high.
There was a thread on the forum about 5 years ago in which some of the more experienced growers tried to collect exact data and record grafting results for peaches. The results were somewhat variable. I’m sure we’ve all become better peach grafters since then.
As Alan mentions, matching diameters helps, and of course a perfect cambium match helps. Also I’ve found grafting to a mature tree is much easier (more forgiving) than grafting to a whip peach rootstock.
I’ve had better success using this tool, which offers a lot of tightly fitting cambium match.
Some of the grafting tools break (like mine did) but Danchappell had a good idea for an easy fix in the thread. I had a more elaborate fix for mine, which I showed at the end of the thread.
I really like the tool. It’s fast and accurate.