Fleeced

Fleece, originally uploaded by peganum.

I seem to have erected a tent inside my greenhouse. I lost so many things that were supposed to be protected in the greenhouse last year that I've just lined the entire thing with fleece this year (and installed a fan-heater.)
There was the option of using bubble wrap but, besides being pricier, it also accumulates condensation and then drips, which can lead to botrytis (grey mould) on any dead, sick or weak vegetation.
Some plants from Mediterranean and subtropical climes, although potentially hardy enough might not be used to the kind of dank overcast conditions we get. If you keep them too warm they may try to grow, but without enough light and heat the new growth may be pale and weak and prone to moulds and aphids.
The fact is, winter protection of tender plants is always a balancing act between keeping just enough warmth in, not letting the air stagnate and providing as much light as possible.