I too have done it in spring but am trying it now with rhizomes I dug a few weeks ago. I brought these into the house and planted them shallow. I have a couple of shoots so maybe it will work.

To state the obvious, wouldn't it be grand? Since we root prune in Oct/Nov, I mean. Since there were 2 of you trying this out there, I put 3 Vivax rhizomes in pots yesterday. No harm, no foul. How are the new shoots prospering, Thuja?

I am getting some shoots but not as many as from early spring-harvested rhizomes. They might need some more time.

Puiugrosu, Thuja: I have wondered if a rhizome root could remain "in stasis" if put in dark moist earth, but not watered until spring, kind of like a Begonia Bulb? Then I thought about keeping a rhizome frozen, until spring. The idea of a frozen rhizome root (with healthy "filament" hairs, interests me. I think I will try it both ways.

Yes, I think they are dormant. I put mine in warm area to see if they'll "wake up."