"Kay wrote in message

As to protection, I don't know. Mine are in the greenhouse, which is
frost free, and usually 40 deg plus at least in daytime. I had a glut of
them a few years ago and tried some outdoors - they lasted a couple of
years.

I know one gardener around here that does not dig his up for the winter so
I'm not going to disturb mine either. :-)
His seed around too! (so he says)

p.s. my 8ft+ Dahlia imperialis (thanks Hill House Nursery) took last nights
frost without problem much to my surprise so you can never tell. All the
Dahlias down the allotments died back because of frost a couple of weeks
ago. I leave them in too year after year.(planted deep)

--
Regards
Bob

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