[Yana]

I've put a load of lilies in pots and largish containers and they are already showing above the soil/compost level. They are indoors at the moment in a non-heated room that gets lots of light. Should they be moved to a colder place (greenhouse) or top up the soil/compost level to cover the shoots? It's too cold to plant them out isn't it? The ground is not waterlogged but I am sure they will rot as it is so cold.

[Trillium]

Stop watering the pots and you can put them outside in a sheltered area for now.  This way they can start to harden off (get used to sunlight) and be ready for a better planting out time later. They can take a lot of cold but any frost directly on them will kill off any flower buds so the shelter should protect them.