I agree with Iain that planting things where they will not get the morning sun during freezing spells is helpful. Parts of my rock garden are in sun during summer, and in shade in winter when the angle of the sun is lower. Many days these areas stay frozen all day. The "fleece" that Iain mentions sounds like the product sold in the US as Reemay. I use it to wrap some container plants during severe weather, and also to cover amaryllids in spring against bulb fly. It's mostly used as a row cover in vegetable gardens and can be bought from organic garden supply companies. I also use a thicker product, called microfoam, to protect my bulbs inside the frames when the temperature drops below 25 F or so. I lay it directly on top of the plants and shut the frames. I get it from a nursery supply company -- not sure where it would be obtainable in an area not so heavily populated with nurseries. It has a waterproof layer and a foam layer, bonded together, and is very light. Jane McGary Northwestern Oregon, USA