In article , JennyC
writes


I have a glass GH at the moment, but was wondering whether a Polytunnel would
surfice until I can get myself organised properly (i'm not sure yet about
building restrictions as the house is in an area under monument rules)

I think your problem will be the damp not the cold. If you can keep them
bone dry in a dry atmosphere, they will tolerate cold better, if wetter,
then they won't be cold tolerant. So do whatever you need to avoid
condensation.

Trouble is that the damage isn't instantly visible. Plant seems to look
OK, it's only in the spring that the top falls in and you realise the
inside has rotted away long ago.

My greenhouse goes down to 40 deg F with occasional overnight drops to
34 deg. We always get a few losses, but only a few plants in a
collection of hundreds. We grow mammillarias, rebutias, astrophytums,
lobivias, gymnos, echinofossulocacti and a few other O&S


--
Kay
"Do not insult the crocodile until you have crossed the river"