So when low temperatures and high winds arrive, the leaf valves close. By looking out a window on a winter day, one can determine roughly how cold it is by the degree the rhododendron leaves have curled and drooped. When temperatures rise, the leaves open again. Rhododendrons are also subject to leaf scorch in winter months, particularly in January, February, and March when the sun marches northward. Winter protection in severe climates can be given a rhododendron by means of temporary windbreaks or spraying the leaves with anti-transpirants.
Rhododendrons also thrive better when mulched with loose material after the ground has been frozen.