Improving Mariken Ginkgo nebari

[Rambles]

As I am still getting to know my recent acquisition, I discovered that the trunk's "surface flare" is actually a knuckle that resulted from grafting and that the trunk narrows down again below the surface. There is about a 1.5" space from where the roots are to where I would like them.

"No prob, Bob! Just groundlayer it!" you say?

Any other deciduous I would in a heartbeat, but a couple things here gave me pause and I wanted to run it by others:

Ground-layering at graft scar: the widest point of the trunk looks like it was either the site of a big cut early on, or more likely, a pretty nice whip graft. Some of the stock tissue extends above where I would want the nebari. Is this ok, or would it be ill advised?

Girdle vs Tourniquet vs ?: Most of the ground layering I've done has been girdling higher up on trunks. Considering that there isn't much space between the current roots and when I want them, and that ginkgos are supposedly slow to heal, would twisting a wire below the bulge and waiting a couple of years be a better choice? I've seen references to creating an injury that you keep open until roots form. Is that a viable route?

If you use the tourniquet, when, and do you still use rooting compound?

Picture available shortly.

 

[Rambles]

full tree, proposed front
knuck at front
left
right

And a correction on original post, it's 1.5 cm, not 1.5 inch between current root tangle and the knot of the wide spot. Thank you.

 

[Leo in N E Illinois]

So you only have to move the roots up a little over 1.5 cm, or a little over 1/2 inch.

If you were planning on doubling or tripling the diameter of the trunk, by growing it out for a number of years, I would say you need not bother. It would very likely become invisible as a graft. But you would need enough growth to at least double the diameter of the trunk.

If you are not planning on significantly increasing the trunk diameter, I would go through the trouble of layering. All my attempts at rooting ginkgo cuttings have failed. This is only cited as an indicator of how easy a ground layer would be. My guess it would be a minimum of a 2 year process before roots would be well enough established to do the repot and cut off the lower understock. If you are not planning on increasing trunk diameter significantly I would cut to expose cambium to do the ground layer. Bury the layer deep, at least 1 to 2 inches of media over the top of the layer.

I have never done a ginkgo ground layer. So I can not speak from experience. I would probably choose the tourniquet method, with the caveat. Repot the tree into a pot where you can leave it undisturbed for up to 5 years or more, plenty of room to grow. apply the tourniquet as you repot. If it is not extremely tight, you will delay the cutting in for a year or so, which would give the tree time to establish a vigorous root system. As the trunk increases in diameter, wire will bite in more and more. Eventually roots will form. (hopefully).
It is important that there be at least one inch of media above the ground layer. Too shallow and it will dry out too easily. resulting in no new roots. Bury it deep. Then leave it alone. When there seems to be a geometric increase in growth, the following year repot and see if the new root system had formed. But don't rush. It could easily be a 5 year wait. Maybe as little as 3, but it could take a long time. Depends on how slow growing your ginkgo cultivar is growing. I know it is a dwarf, with a reduced growth rate, which could easily add many years to any project.

Good luck.