Probably the most misunderstood and least utilized technique available to a bonsai artist is grafting. A few years ago my uncle Pete Jones taught me how to graft and every spring since I have used this technique . Last fall Pete began talking about getting a few buddies together to graft and share desirable material. By the time our gang of 4 ( Pete, Will, Ted and myself ) had finally decided on a suitable date word had gotten out and many people were requesting to join us. So Pete decided to make it an open invitation and over 20 people attended his Grafting Symposium in Arlington, Virginia.
Before I get to the symposium demonstrations I will very briefly explain grafting. Grafting is horticultural technique that joins together the vascular tissues (cambium) of a rootstock (tree) with a scion (short branch tip or bud). For the graft to take (be successful) the 2 cambiums must grow and fuse together. There are several types of grafts, but for this post we will only discuss two, peg grafts and side cleft grafts. There are many advantages to employing grafts. One is adding a new branch or branches to a tree where none exist. Another is to add a new desirable tree species to a compatible trunk. In the following demonstration Will Feldman grafts rare short needle Japanese black pine buds ‘Kotobuki’ (the scion) to standard Japanese black pine trunks (the rootstock).
Will Feldman began by demonstrating the first of three grafts. Here Will is scraping bark from the area he is going to insert a scion to create a new branch using a peg graft technique. This scraping is done to keep the wound clean and free from debris when the cut is made.
After selecting the new branch angle Will drove a chisel into the tree. Wow! I had never seen anything like this before. The depth of the hole and the length on the scion must be the same for the cambium to match up.
Next Will cut a scion to expose the cambium. The cambium is the green layer beneath the bark. The cut forms what Will called a narrow smile of green cambium. The trunk has a broader smile because it is a larger piece of material.
Will inserted the scion into the hole trying to match as much of the 2 cambium smiles as possible.
Will then wrapped moist sphagnum moss around the wound and wrapped it securely with grafting tape.
Will then took a plastic sandwich bag and covered both the bud and sphagnum moss to keep the bud from drying out while the future branch grew in it’s new home.
Here Will is demonstrating how to apply a scion to the base of a tree as low as possible to the roots using a side cleft graft technique. Will makes a small cut leaving a flap to slide the scion into. This technique is used to add a desirable scion to a compatible rootstock. This is a great inexpensive way to obtain new and rare trees. After the graft has taken the rootstock tree is gradually reduced until it is finally removed above the graft and you are left with only the desirable bud which then grows into a full tree. Any growth below the graft is from the original tree and needs to be removed.
The scion was cut and inserted into the flap that was created. He then matches the 2 cambium smiles and wraps the area with grafting tape.
Moist sphagnum moss is placed into the bottom of the pot and the whole tree is placed into a clear plastic bag to keep the scion from drying out until the graft takes.
Here is another standard black pine that Will has made flap cuts to insert several scions using a side cleft graft. After the grafts have taken the top portion of the tree will gradually be removed down to the top scion and the whole tree will now be ‘Kotobuki’. The scion pointing upward will become the new apex. Any newly emerging buds on the trunk will have to be removed because they will be from the original tree.
A few notes to improve success.
The scions should still be in their dormant phase and the rootstock should be in an emerging growth phase, generally 1 – 2 weeks difference. You can cut the scions in advance, place them in a plastic bag with moist sphagnum moss and refrigerate until the rootstock is ready.
The two smiles of cambium rarely match up perfectly because the scion and rootstock are usually different sizes. Make sure that you match at least one side and the top.
Professional growers keep grafted material in a greenhouse with a plastic tent covering to increase humidity and keep the scions from drying out. Hobbyists can use clear plastic bags and monitor moisture until the grafts take.
Even professional growers experience failure in grafting, hobbyists should expect a 50% to 80% success rate depending on their experience.
Give it a try!