The big shishigashira bonsai project

Back in April 2019 I was given a field grown landscape tree as a birthday present. It is an Acer palmatum 'shishigashira' , several wonderful bonsai specimens of which I had seen on my then recent trip to Japan. When I spotted it at a local nursery, in late 2018, I thought it had good potential for bonsai; it's probably 20 years old or so, with some good taper and movement, and is not grafted. The nursery staff seemed quite surprised that we wanted to buy it, as it was the centrepiece of their Japanese maple display and the most expensive plant in the nursery... I'm lucky to have a sympathetic and munificent wife!

Unfortunately I don't have any photos as it came to me, so I'll share an image of one of the fine shishigashira bonsai from Omiya Bonsai Art Museum, Saitama (image courtesy of that institution). The autumn colour of the crenulated leaves gives rise to this tree's cultivar name, which means 'lions head'. Of course, my lowly specimen is around 100 years younger than this masterpiece!

My plan for the tree was to air-layer several smaller trees from the upper branches, concurrent with using wedge cuts to perform staged removal of some very big branches. The wedge cut technique was innovated by Mr Ebihara, a Japanese master of deciduous techniques. In essence, the branch to be removed is  half cut through, preventing die back down the trunk, and supporting callusing of the large wound on the desired trunk line. There's a nicely illustrated post on Kaya Mooney's blog here which features the technique.

In February 2020 I reduced the root-ball by half and removed all the field growing soil, replacing it with a coarse mixture of moler clay, pumice, and pine bark (5:3:2).

Once the leaves had hardened off in late spring I started my air-layers and first notch cut.

Then in early Autumn I separated the successful air-layers (when I say successful, they all had roots... but I'll probably need to do extensive root grafting to make up for their asymmetrical distribution, if they thrive this year) and made a second notch cut. 

After leaf drop I also made a thread graft.

Above, the tree at present with notch cuts, thread graft, and the site of the next air layer marked.

Below, a mock up of the next stages in the plan.

In May 2021 I'll start one more air layer, removing it in Autumn again. everything will be allowed free growth to facilitate healing and build up energy. At the moment my plan is to remove the branches supporting the notch cuts in late spring 2022, but I'm going to take some professional advice on that.

The first image in this blog post is a rough plan from 2019 of where I'd like to take this tree, it'll take me decades to achieve it, but hopefully I'll be given that time!