I'd wrap the pots with bubble-wrap or similar if they are ornamental and water sparingly only when the compost is dry. Remember on sunny days the greenhouse may get very warm, so be prepared to open the door a bit. Small acers may benefit from them being knocked out the pot and checked for vine weevil grubs. Wash the roots and repot in fresh compost.

Thanks, SBG.

I have never yet protected an Acer during the winter - they seem to be perfectly hardy in a fairly sheltered spot. But Eileen is definitely our resident expert, so probably best to do as she advises 🙂,

I was concerned for the very small ones, Sheila, but as I say, I have lost some in the early spring just after the leaves formed on them. Very strange.

if they start to leaf up when under shelter of the greenhouse they will need hardening off before going outside fully. late frosts will also 'do' for them

They died inside the g'hse, Sbg..

too hot possibly? I lost quite a bit of stuff in the warm spring as I hadnt kept the automatic vents in place and they cooked.

Thanks, both.