J. Denys Bourque wrote: "I suspect that dessication due to wind effect may be the cause that plants in pots left to overwinter outside die, particularly if snow cover is lost." You might be right - we rarely have snow cover here, and desiccation is a likely cause with potted conifers in pots in the wind swept canyons of the inner city. But I've had this happen with plants in my own garden which were in relatively protected sites where wind and desiccation are not likely causes. Jim McKenney