I don't know the answer to the question, I'm afraid, except that, with a
bit of luck, there might be more buds below the surface of the compost,
which might sprout.

I'm interested in the hardiness of C. sieboldii generally as well. On
Rachel Sullivan's excellent website, (http://www.ukclematis.co.uk) she
says that Clematis florida 'Sieboldii' needs a "very sheltered
site/conservatory". In one or two other places I've looked it doesn't
specify so much protection, but obviously your experiences too suggest
that it's susceptible.

I wonder whether Rachel or anyone else can comment more fully? My baby
plant is standing outside at the moment and seems to have survived
recent frosts.

Janet G

Hopefully Rachel will spot this thread because I gave up growing this
variety, It is not frost tender as such but seems a lot les robust than
other clematis and I would concur with the grow in Shelter advice. growing
in a pot is fine and I would expect it to reshoot from below ground. In the
mean time remove all dead and dying bits.

--
Charlie, gardening in Cornwall.
http://www.roselandhouse.co.uk
Holders of National Plant Collection of Clematis viticella (cvs)