AusBonsai

There are a number of ways to get new roots on your bonsai. Grafting is one possibility and there are also several different techniques to graft roots.
Here's a couple that I use.

The first subject is a small trident. When it was pruned hard a section of the trunk died but I still thought it had potential so a few months ago I hollowed out the dead part of the trunk with the dremel. Now the trunk looks OK but it only has 2 strong roots. To make a decent bonsai tridents really need a full, strong nebari so I'm going to try to add more roots. This time I'm thread grafting seedlings through the existing strong roots. Eventually the top of the seedling will be cut off leaving the roots grafted onto this trunk.
Drill holes using a drill bit large enough to get the seedling through. I've used a 5mm bit for these. There was only room to put in 3 grafts at this stage. Others may be added after these ones heal up. Now just seal around the graft sites and put it back into a grow pot.

Great post Neil. Yes thread grafting with seedlings are a great technique and seems to work very well with maples. I have not tried this technique on other species yet.

Excellent pictures Neil, could not be made any clearer
Cheers
Bob.

Example 2 is a Japanese maple. I've tried to do a root over rock but the roots that should have gone right round the rock failed. Now the growing roots will push the tree away from the rock. Grafting a seedling where the root should have been may save this one. Afterward it was wrapped up again and planted deep again.

Hi Neil

Great post mate. I'd never seen this done before. I thought you would have to take the bark off the sapling but it looks very straight forward. Couple of questions...would you do the same for a branch or is an approach graft better? And what do you use to seal the wound?

Chris

Great post Neil, and great idea with the ROR!

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Hi Shibui,

Great explanation and pictorial references as usual, much appreciated!

Just wondering if it's possible to thread graft the thread graft ... and in effect build a bit of root ramification like the image below ????
Maybe that's too much in one season ... I was just curious.

Great post sir Neil.


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Shagga: Taking some bark off the seedling can help it join up quicker and more reliably. I have done that in the past and then wedged the cut areas to hold them in close contact so the heal properly. I could have done that with the JM but some of those trident seedlings I used are a bit too small to scrape bark off. When you don't take any bark off this relies on the seedling growing bigger than the hole then getting constricted. It then starts to callus where it is trapped and the callus on the seedling should join up with the callus which is growing to close the hole. As long as both stay alive for long enough they should join up.
It can still go wrong. I have had instances where the top part of the seedling grafted on and grew really well but the root side did not join up and died because the food coming from the leaves was taken by the larger tree
You can definitely use this to graft branches. In fact I think it produces better branches because you can insert the new branch at whatever angle is needed. Approach grafts need to go across/up/down the trunk/branch you are adding them to and can look odd.

Ryceman: That could be done but drilling a hole through that seedling would require great precision and you'd only be able to get a tiny seedling through such a small hole. Until you have done this you don't appreciate how large the hole needs to be. Maple buds stick out proud of the trunk opposite each other. That effectively makes the hole needed to get them all through about twice the size of the actual trunk that you are threading through the hole.

shibui wrote: Ryceman: That could be done but drilling a hole through that seedling would require great precision and you'd only be able to get a tiny seedling through such a small hole. Until you have done this you don't appreciate how large the hole needs to be. Maple buds stick out proud of the trunk opposite each other. That effectively makes the hole needed to get them all through about twice the size of the actual trunk that you are threading through the hole.

Really cos it all seemed to work fine when I was doing it with Photoshop...
Thanks for the reply.

Hi Neil,

I have no intention of hijacking this fantastic thread, but could not think of a better place I could contribute to this topic with the technique that I have been using to improve the base of tridents lately using your most awesome seed - approach grafting.

Here is one I did today:

Take one trident that could do with a little extra flare (is there one that doesn't? ), or a gap or two filled in the nebari.
Prepare roots as per normal annual groom.
Take one bunch of prepared trident seedlings:
Make a neat groove the same width as the donor seedling, and at least as deep as the seedling thickness, so that it will lay flush or deeper when set. I use a Dremel for the groove.
Take seedling and shave contacting sides with a razor blade - I try to select seedlings with a bend in them, rather than dead straight, and orientate them so they sit more natural and will create a root that moves in the right direction. I shave two sides in contact with parent cambium, as I find callous formation on both donor and parent forms a more reliable union:
Set seedling in the groove - it should be snug, with shaved sides contacting the exposed cambium of the parent at the edges of the groove. I also leave the tap-root in place for better growth and thickening.
Secure in place by using a mapping pin, piercing through the centre of the seedling, and all the way in as far as it will go. the plastic head on the pin helps to set the seedling in tightly and flush:
Repeat as many times as you need. One this one, I set five:
Wire the tops of the seedlings outward so they can enjoy the light and grow. This also minimises congestion with the parent tree as they grow. I seal with cut paste (the putty kind) as I find it aids callous formation and union. I cover the cut paste in foil because it protects from the weather and from wasps - where I live wasps will steal it as a substitute for clay to build their nests in a day or two. Also, use wire to set the angle of the donor root.
Here is one I prepared earlier. This is one of the trees I performed this technique on this time last year, and placed back in the growing beds. The parent actually engulfed the donors, forming quite a good, smooth union. The resulting root grafts actually look quite natural.
I have indicated the donor seedling and resultant root with arrows. A union is circled in red. There will be a scar when the top of the donor plant is removed, but that will heal in a year or two.
Cheers

Thanks for the great reply Neil.

Hi wrcmad, great post as well mate.

Great contribution to this thread wrcmad, especially those after shots to show what happens.
My next subject is approach grafted like you have illustrated.
This one has great taper and good trunk shape but roots are all on one side so I need to add more roots to the back.

I don't make the groove as deep as wrcmad. Just down through the bark - no need for the dremel, just a sharp knife. I do like to use those L shaped seedlings so the roots come out at ground level. but you can also use seedlings that have a strong root at right angles to the trunk. Just cut off any roots growing on the other side and graft it in.
slice off a thin layer of bark from the back of the seedling to approximately match the groove you cut. Exact match is not important because both trees will stay alive and grow and heal until the cut area meets and grows together. Because I don't cut the grooves so deep the grafted seedlings are usually proud of the host tree. By the time they have grafted the bark is almost all one level anyway I think.

Map pins are too short to hold thicker seedlings in place. Here I've used small nails but I had to drill a small hole through the seedling so they don't split while pinning them in place. Finally seal the grafts so they heal quickly and pot up the tree.

Sometimes I wire the top of the seedlings out away from the branches of the tree. If they are tall enough I just let them grow up through the canopy

Wow! you really nailed it this time, good stuff.

Finally got around to my annual lifting of my field-grown tridents this week for root work. Took a few pics to show what can be achieved when using the root grafting techniques illustrated above in combination with growing in the field.

The three trees pictured below were all struck from cutting in the 2012/13 growing season. They are lifted every year without fail for root work. Since 2015, they have been subject to root grafts where necessary to fill any nebari gaps. The work is starting to pay-off:

For size perspective, the blue tub this tree is sitting on is 350mm in diameter. You can see where previous roots grafts have been performed, and where the trunk has healed after the scion has been removed. This one has had enough grafts, and will be transitioning into refinement:

Another example, no more grafts performed - maybe next year if neccessary:

And finally a third example, where 4 more grafts were performed after the pic was taken:
Cheers