We really babied our bougainvillea plant this past winter. I cannot remember how many nights we went out to this bush with drop cord lights and sheets to protect it from the frost. As I recall, there were more nights that it was covered than it was not! While our winters are relatively mild here in southern AZ, it does freeze and when these plants freeze, they look really bad. I guess this is the way it showed its appreciation for all the covers when the nights got really cold. It was the most gorgeous one on the street and I noticed cars showing down to look at it!