Posted: Yesterday at 09:55
My Mirabelles have finished flowering already, I'm in County Durham. This is just the first full year they've been in. I think you've buried your graft. Have a look at the base of the tree if you can't see a join then dig down gently with a trowel until you find the join.
If you have buried it then uncover it, if any roots are coming from the scion then remove them with a very sharp knife or secateurs. The graft/join should be well above the soil since even an inch above may not be enough to stop the scion rooting in especially since you've mulched. I've got an apple tree that I think has probably rooted from the scion even though it's above the soil. There's roots coming from the join which could be from either the rootstock or the scion and it still hasn't flowered which tells me I need to get the secateurs out.