Hi Grant and others.
This post has quite uncanny timing. A couple of days ago I cut the last of the approach grafts off one of my junipers as well.
grafted juniper.JPG
I have 2 of these. They started life as upright, tight packed conical bushes with prickly leaves. I grew a number of them in the ground for a few years but only dug 2 as a trial. They have achieved good trunk size but the very vertical growth was hard to tame as bonsai and they bite quite severely when I'm working on them so about 5 years ago I decided to try grafting this one to
shimpaku foliage to get the best of the existing trunk and the great foliage of
shimpaku.
My attempts at grafting shoots all failed so I resorted to approach grafts to achieve this.
Some things I have learnt while trialling this:
Approach grafts can be placed at any time of the year but the bark of the stock lifts more easily when the tree is growing during spring and summer.
You need patience. Some of these took more than 12 months to achieve a good union (some grafted reasonably well after just 6 months so it is possible to get quicker results)
It appears best to separate the scions from their own roots in winter. Most that were cut in spring and summer died off - I think the foliage demands more water than can cross the new
graft initially. Cutting in winter allows the cells to realign slowly while the foliage demands are less. With the last lot I did as Jow suggests and removed bark from the scion stems a bit at a time over several months to force the new
graft to take more from the host rather than relying on its own roots for water and food. When the scions had achieved a reasonable union I also cut back the host foliage above the
graft severely hoping that would force the host to unite with the scion more to use the new foliage to survive.
Allow another 12 months before trying to wire or bend the scions. Initially there is very little holding them together and I have broken 2 of the last summer grafts off this tree while attempting to shape it this week. The central trunk with the remaining stock foliage has been left because it has another late approach
graft at the back.
Over winter I will try to find time to carve the leftover branches of the stock plant as jins. I'm hoping that this will end up being a juniper with lots of dead wood like you see in Japanese pictures

It is certainly a good way of producing advanced trees with desirable attributes quite quickly - wish I had dug the rest of them now
