I couldn't help noticing as I toured part of the garden a few days ago how two young Rhododendron dauricum plants had reacted so differently to the cold. Curling of rhododendron leaves, as a response to frigid temperatures, is a natural reaction, though the mechanism that triggers the curling is poorly understood. (see http://www.arnoldia.arboretum.harvard.edu/pdf/articles/1990-50-1-why-do-rhododendron-leaves-curl.pdf). These two seedlings were raised from the same seed source (Hokkaido, Japan) in 2012. Both have been growing side by side in the garden bed for over a year and have been treated in an identical manner. The one on the left is obviously not as concerned about adverse weather as the other. Rhododendron dauricum is very hardy to begin with but apparently some individuals are more tolerant than others, and when it blooms, that is the plant from which I will collect seed.