Though we think of iris being totally dormant during the winter, they really aren't quite, and here in Maryland, at least, there always remain a few green leaves that are photosynthesizing, and makng food they need to run their "stepped down" metabolic processes. I somehow doubt they would initiate buds if they had absolutely no light by which to run that energy-requiring process. I like Tom's suggestion of leaving them outdoors and applying ice.
