I think I saw chunks of pumice at Jasmin -- is that where you got yours ?
I hope its worth the trouble...
I think I would just go with clean sand, as a more convenient alternative.

Funny, some of the trouble we go to, to germinate seeds: some of the ones I got from S-W Australia this spring required that they be "smoked" :O)

Good luck on yours!

That's the stuff I saw this morning, at Jasmin's! It was quite a crowd. The fellow there suggested sand. I have some anyways, so I might try that.
I saw your earlier post. Did you get 'smoke'? How was germination? If they are planted outdoors can you let me know what street to visit to see?!

Yes, I managed to produce smoke, without burning down the house.... (or smoking anything illegal or otherwise)

My big mistake initially was thinking that seeds from Oz would germinate better using a heat pad.
Nothing came up for over a month.
As soon as I took the heat pad away, they started coming up.
Not everything, but quite satisfactory.
Next hurdle is not loosing all the seedlings -- their growth rate is incredibly slow.

PS. These are essentially desert-type plants, so need to be moved indoors over winter....