Doing it in the growing season will allow the rootstock to send nutrients up to the graft so that it can stay alive and they also grow and connect/scab over into one plant. In the winter the graft will probably just dry out from the winter wind.
But give it a try and let me know how it turns out. It never hurts to try. And if they all die by spring you can do another graft again.
I did my grafting onto existing trees as those trees were budding out and that worked nicely - 10 of 13 survived.
If you're grafting onto bare rootstock, I think the preferred time is about when the snow is melting. That way they can callus over for a few weeks before you plant them out. I was told you want to plant them out after the deep freezes are over.
"Hundreds of years from now it will not matter what my bank account was, the sort of house I lived in or the type of car I drove... But the world may be different because I did something so bafflingly crazy that it becomes a tourist destination"
Location: North Carolina zone 7
posted 1 year ago
I may give it a go soon on a couple grafts just to see what happens. Will definitely do it closer to spring as well.