I had on my bonsai bench from 1994-2005 a sole example of the smallest azalea I ever ran into. I was not (but probably should have) propagating in those years, and have spent the time-between wishing I did.
i went googling from time to time without luck. This year I fell into a good ID for my missing shrub, Rhododendron fastigiatum. Note I called it an azalea, and I still think it is, but the taxonomy guys are not smelling what I’m stepping in,
I can find British nurseries with this little shrub, but I don’t think I can buy from them,
I have gone back to the rhododendron society’s “nursery finder” and sent off begging letters to every nursery on their page that gives an e-mail to try.
If this don’t hit pay dirt, I dunno what else to do to shake one a these out of the either.
I expect you have probably already called them to ask about small azalea’s, but if not, Betty’s Azalea Ranch, which is in our area, might be able to direct you if they can’t pull it themselves. Also, since naming doesn’t always seem to be consistent, it might be worth it just to ask what the smallest one’s they have are.
Finally, you might also want to try calling Shanti Bithi in Connecticut to have them tell you what they have as starter stock (or can get). When I’ve been there in person I’ve seen some very small leaved azalea’s offered as reasonably priced plants. These are the starter types that aren’t much more than a promising plant trimmed and put into a bonsai pot. My last visit there was quite a while back, but they do seem to have pretty good connections for importing plants.
Now you have me curious about these as well. Will you grow it as a bonsai and if so do you expect to get much thickness in the trunk? Or will it be used for Mame bonsai, so you need the tiny size leaves?