>The duration of the freeze is irrelevant: one night's freezing solid of a pot will do the damage. I probably missed most of the discussion. The reason why bulbs are not very hardy in pots is that the bulbs themselves are not very hardy. This may sound counterintuitive, but a bulb, being buried in the ground, has no adaptive reason to develop hardiness to cold. Most bulbs are not hardy at temperatures approaching -10C. The smaller the volume of soil, the easier it is for cold to penetrate. I've killed hundreds of tiny calochortus bulbs this way, until it dawned on me what it was I was doing to the poor little bulbs. There is an excellent discussion of this in The New Plantsman, September 1994. "Frost hardiness of bulbs". Bob Nold Denver, Colorado Z6