8-10 inches English Elm with big hole in trunk. The material has been grown for many years, building up good branch movement and ramification. However it’s not without its faults. The thing about ‘faults’ in bonsai material is that they can be made advantages if you can find a way of using the fault as a feature or rather as a way to tell a story about the tree.
The Elm used has some bad negative taper and empty space just above soil level. One possible way to improve this would have been to air layer above the negative taper part. Grafting on new branches low down would also be a way of eventually correcting the negative taper.
However if your fortunate to have better examples of the species in your collection then an argument could be made for trying something different…
The plan was to have this Cotoneaster grow out of the central hole in the Elm trunk. This would then be two very different species growing on one trunk. during winter time I’ve noticed large oaks with evergreen Ivy growing close to trunk, and wanted to make something reminiscent of this.
The Elm root ball was gently broken down around the edges, very little root grew from below the trunk as the bonsai had been well cultivated in previous re-potting over the years.
A hole twice the thickness of the Cotoneaster trunk was drilled and a slight hollow cut in the base of the Elm trunk. We wanted to give the Cotoneaster roots plenty room to compete with the Elm.
Cotoneaster was bare rooted and any roots high up were removed. The trunk and roots were then tightly bound to a thick piece of wire using natural twine. We used twine because it would rot, just in case we weren’t able to remove it all once finished.
The Cotoneaster root can be seen in the centre of the root ball as indicated by the chop stick.
Here are the two plants combined. The excess Cotoneaster branches will need to be pruned but this was not done at this stage because we wanted to ensure the Cotoneaster would have strong growth to enable it to recover from the operation.
Over the coming years the Cotoneaster will be pruned to grow into the blank space low down on the trunk. There is also the possibility of growing the Cotoneaster out of the nobble on the right hand side.
There are two challenges to over come here; firstly the two root balls will need to be pruned to balance the competition between the plants growth. Remembering this idea emulates the Ivy growing on Oak trunks in nature, Ivy is extremely shade tolerant, so it is able to take advantage of the shade whilst using the Oak for support. So the second important challenge will be to prune the Elm carefully to ensure it doesn’t shade-out the Cotoneaster when in leaf, during the growing season.