Snow is the best possible protection during the winter. However, it is rare to have a thick snow on the island and quite often the snow melts during warmer periods of the winter. I do protect the young and tender plants. I have lost only some rhododendrons and winter damages have been at a tolerable level. I'll try to avoid too tender rhododendrons and I have used the winter hardiness limit -24°C (-11°F) as a general rule. As an exception to the rule I have some plants hardy only to -21°C (-6°F), but well protected during winter.