Suppose you want to create a bonsai. You start with two things, a bush and a vision of what the final bonsai should look like. With some luck the bush will have just the right number of branches placed just where you want them. If it has some extra branches they can always be cut off. What happens when the bush has a bald spot where your vision requires a branch? Occasionally you can do a comb over to cover the bald spot by positioning an adjacent branch but more often the comb over looks exactly like an attempt to hide something that is not there. Be of good cheer, though. All is not lost. You can graft a new branch exactly where you want one.

The concept of grafting is deceptively easy. It involves bringing together living tissues of two plants. They fuse together to form a single plant. To understand this process more deeply, we need to look at a bit of plant physiology. Trunks and branches have a very thin layer of active tissue directly under the bark. The interior is wood and is no longer living tissue. This thin layer is known as the cambium. When a cut is made on, say, the trunk of the tree it is the cambium which causes the tree to heal over the cut. If the cambium layers of two different branches are placed together, they can fuse together to a single unit.

The mechanics of the process to form a graft are simple. Typically, a narrow slit is made on the trunk or branch to form a large splinter and a twig is placed in the slit and the twig starts to grow as if it was part of the original tree. And there you have it. A branch just where you needed one. The actual mechanics of grafting, while simple in concept, are a bit demanding in practice. First all cuts must be made with a very sharp knife. Dull knives crush the cambium layers rather than make a clean cut. Crushed fibers grow slowly if at all. The ends of the twigs are cut with two cuts to form a wedge-shaped point. The more surface that the twig and the slit on the trunk come in contact the more likely you will have a successful graft. Care must be taken that the cambium layer of the twig exactly matches the cambium layer of the trunk. Once the twig is installed the cut surfaces must be protected from drying out. The cut areas are protected by tightly wrapping the union with a variety of ties, including raffia, rubber bands or Pliofilm all of which work well. The twig will dry out because it can lose water through the leaves but has no means of replacing the water until the graft takes place. This can be prevented by placing the twig in a plastic bag which takes some juggling to be effective or wrapping the twig with Pliofilm. This technique is lovingly known locally as an asparagus graft because the wrapped twigs look just like asparagus spears.

You can tell when you have made a successful graft when the twig starts to grow, and this usually takes a few months. This process sounds simple, but the sad fact is that despite your careful efforts the success rate for a successful graft is frequently low due to improper technique or to the fact that the tissues just do not want to cooperate. With practice, the success rate becomes better but even the most experienced people have less than 100% success rate.

There are several variants of the grafting procedure. Branches can be cut squarely at the end; the cut end is split, and the twig is placed in the cut. Many maples available in the nursery trade are grafted this way. Approach grafts are made by cutting a thin strip from both the trunk and a seedling and the two cut surfaces are tightly bound together. The seedling is left in its pot and thus has less tendency to dry out than a cut twig since the pot can be regularly watered. Once the two are growing together either the root end below the graft can be removed or the upper end can be removed if the objective is to enhance the root structure of the tree.

Another variant is the thread graft in which the tree can grow a long whip-like branch. A hole is drilled completely through the trunk and the long branch is bent and threaded thought the hole. The surface of the whip is lightly abraded to expose the cambium layer so fusion can take place. The hole is then sealed with cut paste. If the graft is successful, the base end of the whip is then trimmed. The thread graft solves a problem that can be encountered with maples. If you select a twig from a different maple, it may have different properties such as leaf size or color than the host tree and this can detract from the tree. Thread graft means that the new branch will be exactly like the rest of the tree.

Can you graft a twig onto a dead branch? The answer is yes, well, sort of. This takes us to a procedure known by two romantically inspired titles from folklore. Locally it is known as a phoenix graft because the Phoenix arose from the dead. In Japan it is called a tanuki, the Japanese word for badger. In Japanese folklore the badger is a trickster who makes people see things that are not there. The process involves taking a piece of deadwood and cutting a groove in it. A seedling, usually a juniper, is placed in the groove and is tightly bound either by raffia or wood screws. As the seedling grows it appears to be part of the tree and gives the illusion of a large bonsai.

Grafting is a skill that all accomplished bonsai artists should have. A great way to start is to practice by grafting on an inexpensive juniper. When you can make a successful graft, you are then able to attack that bald spot in your prized bonsai.