How do we improve grafted areas on our bonsai?

Many of us are confronted with improving poorly grafted sites on nursery stock we purchase. For Japanese white pine, grafted trees are often the only ones available in larger sizes. Grafted trees are also common for various Japanese maple cultivars. Air layering is often a suggested remedy but at a recent club meeting the owner of a nursery had doubts about the viability of the tree’s new roots after having numerous failures. This anecdotal perspective has to be put to the test.

But for pines, air layering is an unreliable option. Are there other methods of improving the unequal swelling of the trunk and the root base? In the book, “The Bonsai Art of Kimura” p.151, Mr. KImura makes 1/2 inch cuts in a narrow area of the trunk in order for the scar tissue to enlarge the area. This was not a grafted tree but could the same technique be applied? l also recall Mr. Kimura drilling a number of small holes to achieve the same affect but l can’t remember the source. There is also the question of difference bark appearances of stock and scion.

My main point here is to solicit the ideas and experiences of other Mirai members in order to conquer new ground by coming up with techniques that can mitigate poor grafted areas and thus improve our trees and expand the usable nursery stock available for bonsai for everyone. Let’s take that Mirai ethic that challenges every notion that starts with “you can’t do that” without making a serious effort to find solutions.

Below are some examples of the grafted problems l am talking about.


Beware of the process in the Bonsai Art of Kimura for thickening trunks. Ryan mentioned in part 5 of the podcast on the book that it was not an accurate translation or description.


Great question @DavidJ
I can only tell you what I have tried that has not worked. Firstly, I have tried girdling the trunk with thick wire and bringing the soil level above in the hope that roots would sprout above the wire. Tried on blue spruce and Scott’s pine. Both trees eat the wire and attempted to bridge the girdle. Could have been me and not the technique?
Secondly, I have tried grafting 5-6 seeds (2-3 years) around the trunk, above the the poor graft on a JBP. Last year all the seedlings died (definitely me) and so far this year on a repeat procedure, I have 1 left and another on its way out.
I’m coming to the conclusion that it’s better to let the trunk thicken.
Also, not all maples are the same. Some air layer easily and others, not so.


Thanks nmhansen for the heads up. l just listened to the Kimura podcast #5. Too late for me. l applied the technique by cutting into the tree as outlined in the book last week.:sleepy: But now the rest of the group knows except for those who already listened to Kimura podcast #5. But the interesting revelation is that even though the info in the book is inaccurate, Ryan observed Mr. Kimura apply another technique that works. Ryan says that he wasn’t supposed to see the technique but inadvertently did while watering and that it is not his to share. That is Ryan’s honourable choice. Now it is up to us to find out the answer.

Don’t feel bad about your misfires. Ryan says it is difficult to graft roots on pines. Ditto for air layers. l did use a tourniquet on some long roots on a collected picea glauca (white spruce) and got roots. Now the tree can fit into a pot. Although that was only roots, not an entire tree. Maybe the wire needs to be the biggest you can find and double or triple wrap it. l am going to try some root grafts on a pinus banksiana (jack pine) this fall. Ryan says it is a good time then with less sap flow. None of these examples are graft related problems but the technique might be appliable. Still hunting for better answers. Thanks for joining the posse and sharing your experiences.


For what’s worth, the two cents I can add to the discussion is that in cases where the graft site is not to high up I would try to girdle it with thick wire not on the hopes of creating roots but rather on the hopes of creating at least a faint hint of a nebari and then burry the trunk up to the point where that new fake nebari was created. This could work on trees 1 and 2. In the case of 3, I would consider creating scratch lines in the trunk perpendicular to the graft line all across the trunk over a number of years so that scar tissue is created in a way that fuzzies up the graft line or planting it sideways almost as if you were going to make a raft style planting and again try as much as possible hide the graft line or a considerable part of it. Frankly, I feel that unless it is buried or hidden by a rock or the attention taken of it by a prominent shari, it will not really work well, I feel it is not something you can get rid of, only mask or take the attention off it. The disclaimer here is that I never tried any of the above as I don’t have any trees with this issue.


Well folks this is a bone that l am not going to give up on easily. The key to this bonsai alchemy is found in Ryan’s comments in the podcast the Bonsai Art of Kimura #5. The pages in the book of the same name are pages 150 and 151. The podcast time is about 14:30 - 26:00 minutes for the entire zuisho Japanese white pine discussion. The discussion of enlarging a trunk area to achieve a better transition of taper starts around 20:00 minutes.

Ryan inadvertently saw Mr. Kimura perform a technique on a number of zuisho pines which he is not at liberty to reveal. Ryan says it is a"fascinating technique…it is complex, not simple to do." It is a technique that does “damage to the trunk without killing it to form the most amount of callus” to repair the area. It is “not cutting” with a knife or “hitting with a hammer”.

The key point is that there is a technique (only for zuisho pines?). lt is not alchemy or myth. It is science. So let’s put our collective heads together and break the code.

lf you damage a tree without killing it, the technique has to be pretty severe that can cause serious damage in a specific area of the trunk. If you can’t cut the trunk or hammer it what about straggling the trunk with a tourniquet? Since damage is site specific you would have to pad the areas you want unaffected and add some bulk to the area you want damaged like brass knuckles. lt would be complex because the trunk is not perfectly round and you would have compensate accordingly. Would this only be done at certain times of the year? How long would the tourniquet be left on or is just enough time to do the damage. Just some thoughts…

Trunk damage with a knife without cutting - this video by Teunis Jan Klein seems to have an answer around 8 1/2 minutes.

Thanks for the input. l saw the video but Teunis seems to have cut the bark with the tip of his scissors. l may try that technique but l don’t think it is Mr. Kimura’s pot of gold. Still chasing the rainbow.

I think the clue is in ‘pierce’ but not cut.

About twelve years ago I had three blk pine on Scott’s pine stock. I twisted a wire around the trunk as tight as I could the twisted a second wire in the same position from the opposite side of the original. Buried all three deep in the garden up to the first branch. Check at two years and roots were appearing at 3 years I was able to remove the original roots

Cab_lad_70. l suggest that you listen to the Podcast l mentioned above. ln the Kimura book it talks about drilling small holes. Ryan specifically said that this is not the correct method. l think it is similar to the “piercing method” that Ryan invalidates. Still looking.

Stevew1 So you essentially ground layered the grafted tree and after 3 years you got JBP roots above the original graft. lnteresting…Thanks for sharing that idea. l wonder if it would work on a larger tree and if a JWP would produce new roots?

You are correct. The Scots pine stock was between 1.5 to 2 inches and the blk pine was between 1 to 1.5 inches in diameter. The trees were very strong when i did this. I tried to layer a white pine in a gallon pot last year and it did not survive.

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Some JWP cultivars are known to ground-layer readily, like zuisho and kokonoe. That is one solution for ugly visible graft points. Example of a large (3’ tall, 60 to 70 years old) successful ground-layered kokonoe

I have 2 young grafted kokonoe currently in colanders that will eventually be ground-layered to remove the ugly root stock. I’m still looking for a set of young zuisho for a project, but they’re pretty much sold out in every place that normally carries them.

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Thanks for pointing that podcast out to me - very enigmatic.

An interesting post from the pacific bonsai museum a little while ago. The third paragraph of the description has some information possibly pertinent to this discussion.