Propagation of Ilex serrata 'Koshobai' – has anyone had success?

[Alessandro]

Hi everyone,
I’m looking for information about propagating Ilex serrata ‘Koshobai’, but there seems to be very little reliable material online. Most of what I’ve found suggests that this cultivar is extremely difficult – if not practically impossible – to propagate from cuttings, air-layering, or seed. The only method that people mention as viable is grafting it onto a standard Ilex serrata.
As far as I know, the regular Ilex serrata can be propagated by all the usual techniques without major issues, but when it comes to Koshobai, there seems to be a real lack of information or anything encouraging.
Has anyone here tried propagating this specific cultivar by cutting or air-layering with any success? Or can you confirm that grafting really is the only realistic option?
I’ve had a Koshobai for about a year now and I would really like to propagate it if possible, so any first-hand experience or practical advice would be greatly appreciated.

Thanks in advance!

 

[Canada Bonsai]

It is a cultivar that cannot be sustained long term on its own roots (as is the case for many species)

there seems to be a real lack of information or anything encouraging

It's well document online (youtube, blogs, websites), in books, magazine articles, etc. and I'm confirming it for you with 8 years of first hand experience with them

 

[Alessandro]

It is a cultivar that cannot be sustained long term on its own roots (as is the case for many species)



It's well document online (youtube, blogs, websites), in books, magazine articles, etc. and I'm confirming it for you with 8 years of first hand experience with them

Thank you for the clarification — that’s very helpful.
If you don’t mind, could you please share a few links or sources (videos, articles, blogs, etc.) where this is discussed?
I have searched quite extensively but most of what I found was incomplete or contradictory, so it would be great to see the reliable references you are mentioning, especially coming from someone with first-hand experience.

Thanks again!