I have found that keeping cymbidiums outside is best if at all possible. I have put spiking cyms inside in a warm room - Bud drop (blast) was certain. If you must put them inside, put them in as cool a place as possible - 60F or less preferred with air flow. I actually took this cymbidium to my society for show after this picture
007 pictures from friends & fun photos on webshots I took the picture after some of the icycles had melted. If you do keep cyms outside below freezing (and I dont recomend it) have a mist of water directed at the plant, It will keep the plant healthy if it doesnt go much below freezing, even if ice forms.