ID phenomena -rose/mum bloom in winter/snow
 

I'm seeking more information about odd bloom habits of flowering plants,
particularly rose varieties and chrysanthemums. An incident occurred where a
single rose, and a planting of chrysanthemum suddenly bloomed in November in
the U.S. region of North Carolina, during a frost. This incident does not
appear to be brought on by a warm temperature spell.

What might cause a break in a hibernation cycle? How common is such an
occurrence? Any pointers to similar accounts or fruitful search terms would
be most appreciated.

Thanks,

Gia