Whenever the opportunity presented itself at a festival, convention or other event I have asked fellow bonsai enthusiasts if they were successfully able to graft on Hackberry (Celtis sinensis). The answer was always in the negative.
I believe that being able to graft is an invaluable skill for any bonsai artist to master or at least be capable in. The styling opportunities it presents are really useful. Sometimes in the design of your tree a branch in a particular position would make such a big difference to the positive and negative spaces or would simply fill a gap in your canopy. However, I find that hoping and praying that a bud will form into a branch in that precise position, especially on a reasonably old tree, is really a gamble which you are most likely to lose.
I regularly graft onto common deciduous species such as acer and ulmus (Read more about this here) but all my efforts with celtis have been in vain. Without anyone locally that has met with success I determined to look internationally for help.
When the chance to visit Taiwan at the end of 2017 for the BCI convention came up, I immediately began looking for a Taiwanese master who would be willing to teach me more about how they create such fantastic Celtis, and of course how to successfully graft with this species.
I am about to show you the two methods which were demonstrated to me and I trust they will inspire you to try it at home.
The Taiwanese bonsai artist featured in this video clip is Master Chang Yong Zhou.
This method is essentially an approach graft, which I had tried many times before. However, on further contemplation it has occurred to me that where I went wrong was that I was trying to graft a tree which was in a relatively confined container and thus possibly not growing as vigorously as it would need to in order for the graft to be successful.
Celtis, whatever the species is which we have here in South Africa, is a slow healer. When you see this, you should expect it not to graft easily either. In contrast the species I mentioned before heal quickly and easily, thus they will also graft easily as the cambium has the ability to fuse rapidly (the reason they are also able to callous quickly).
Although I have not personally tried this method, as I have been focusing on getting the trees I wish to graft on super healthy, I would suggest the following as two requirements for this graft to be successful on Hackberry bonsai:
You will notice the fork in the branch being grafted onto the trunk. Although I am not 100% certain as language was a bit of a barrier between master and student despite the best efforts of an interpreter. I believe the fork serves two purposes; firstly to increase the sap flow and also present a branch which can be used in the future design of the tree which emerges from the trunk at a more natural angle i.e. not out of the side.