Advice on grafting Aztekium hintonii & Geohintonia mexicana please

Hi everyone. I've got seedlings from both Aztekium hintonii & Geohintonia mexicana that I planted. I know that both are considered difficult to graft, but I am going to have a go at it anyhow. Any advice on what size they should be before I attempt this? Any other advice on what works / doesn't work?
Thanks,
IX

Normal cactus seedlings are soft except Aztekium and Geohitonia.
You need a special considaration for these hard seedlings as same as pups grafting.
These seedlings are also quite small and 1 year old ones are easy to handle for grafting.

If you use Pereskiopsis as grafting stocks, you can graft them as same as normal cactus seedlings.
If you use other grafting stocks, you have to give a pressuer on top of scions.
The success ratio of the grafting will be increased when you give the pressure.
I use a small plastic sheet to give the presure.

This comment comes from my experience. Some others may use a differnet method.

The ones that I planted are 2mm wide so far, maybe the biggest is a little more.

Hana, do you have any pictures showing seedlings of those at grafting?

I saw the following images/methods on the net:

video: https://www.youtube.com/watch?v=sYVnoc38ns0

Here is the photo but unfortunately the photo quality is not so good.
Hook the sheet on spines and push down the top of scion.

I used to use a piece of panty hose.
I think the plastic sheet is better because you can see the condition of the scion and keep moistuer.

The top photo of numan's post is similar to but I am not sure the sheets is hooked on spines and pushed down the scion or not.

Thanks, I think I will try the plastic wrap method. I just hope that my scions are big enough. I really want to get them growing, though I don't want to ruin them by trying too early.

That match stick method is awesome so inventive... I love it.

Since they are still growing at a reasonable rate (reasonable for what they are, anyhow), I am going to wait a little while longer before I go and start grafting them.

Ok, tonight I grafted the first of my Geohintonia mexicana seedlings. I'll shoot a pic of it in the morning after some badly needed sleep.

Ok, here's an update photo of one of my Geohintonia mexicana grafted seedlings. I think that the pattern of the tiny spines is really neat to see up close like this.

Here is the same views of one of the Aztekium grafts, though not so nearly as cool as the Geo.
And yes, I have removed the stray Peres spine that I only noticed after I was looking at these photos on my computer.

Awesome job that is a credit to your grafting skills.
How old were the seedlings when grafted and how long since you grafted them.

The Geohintonia seedlings were planted on 5-6-12, and grafted on 13-8-12 (at 70 days old), and the Aztekium seedlings were planted on 14-5-12 and grafted starting on 15-9-12 (at 120 days old).
I had actually started some of the Geohintonia grafts around a week earlier, but after about 3 of them (as fiddly as they were), I decided to wait a bit longer before I continued.
At around 50 days old, I did one of the Geohintonia seedlings onto a hydroponic root stock, and it's going well too.

I grafted these geohintonias when they were some days old, just out of
there shell, in january 2012.
They were grafted without weight on Seleni, Pereskiopsis and Cereus jamacaru.
On C. jamacaru as hypokotyl grafting, together with some Arios.

Just an update on my Aztekiums, the largest of which is 1.2cm across now.