I have been quite lucky that I have been able to visit a number of Japanese nurseries (SEE HERE). I love seeing the high quality trees and amazing level of finish and polish that these trees posses, but what I have also found very interesting during these visits is looking  into the back of house areas where bonsai are in various stages of transformation.

Air layers, grafts and other techniques are all on display out the back of most nurseries. It not only gives you a look into these techniques but also gives you some ideas on what sort of material to apply these techniques to.

One such technique is approach grafting.

A needle juniper is slowly changing its clothes. Soon it will be a much more valuable shimpaku. The white lump is the rootball of the scion which is wrapped in towel to protect its roots.

While I was studying at Taisho-en I was able to see this technique used to improve a range of stock. Shimpaku were given smaller foliage. Needle junipers were given shimpauk foliage. Roots were moved closer to the foliage to shorten trunks. It was obvious that after only a short stroll through their back of house that this was a valuable technique.

The technique itself, whether you are grafting on new roots or new foliage, is rather simple.

  1. Find a scion whip of the same species around 1-2 pencils thick and slice a sliver of bark off opposite sides at the point you want the whip to be grafted.
  2. Cut a channel in the trunk the same depth as the whip is thick.
  3. Widen this channel with a sharp knife to ensure clean cuts. The width of the channel should make a snug fit for the cut down section of scion.
  4. insert the scion into the stock trunks channel. Ensure that the cambium layers meet up accurately along the top edge of the channel cut.
  5. Fix the scion into the channel so it will not move or become miss-aligned. You can tie it with grafting tape or use a nail or two, screw etc.
  6. Cover it all in some type of sealant and wait for it to take.

I drew up a quick diagram to help explain the technique a little.

The scion whip can be from several sources. It could be a long branch doubled back on itself and grafted into the trunk, or could be a small whip that is growing in its own pot. If your scion is of the second type you may need to wrap the root ball in hessian or towel if the root ball ends up in a strange position after being grafted.

How long does the graft take to be successful? That is a difficult question. It is species dependent, growth dependent and also depends on how well you aligned the cambium layers in the first place. Although you can have success with poorly aligned cambium layers in this technique due to the face that both scion and stock support themselves before the graft takes, it is much faster to align the cambium correctly from the get go. I would say that most approach grafts would need one to two years to take. After that you could begin to reduce the original foliage over time and slowly let the new grafted foliage take over.

All in all it is a very useful technique that can be use to get you new roots, new foliage and generally improve difficult stock.

In the next day or so I will be posting a few examples to further illustrate the technique.

To see some real life examples have a look at “Approach grafting 2”.

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