Do you remember reading my blog post "Concerns going into Winter" when I posted the two following pictures?
For those interested, here's two follow up photo's from the same location respectively as those taken above.
Of particular note is the fact that the ice wasn't on the surfaces long enough and or the soil dried down well enough before it refroze to cause any damage to the plant. As you can see in the photo immediately above, the plants adjacent to the ventilation holes are the healthiest. _Mk