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You’ve seen the signs – curled and drooping leaves on your previously healthy-looking rhododendron – and you wonder what’s happening. If it’s the middle of winter and it’s cold, your rhododendron is exhibiting a protective maneuver that occurs during cold weather called thermonasty.
Rhododendrons retain their leaves throughout the winter; that’s what makes them a beautiful foundation plant in our gardens. No twiggy look here, a winter rhododendron still has a great appearance. But when cold weather is around, the rhododendron goes into protective mode.
Does the leaf curling happen to prevent snow burden from breaking branches? Is the leaf curl a protective mechanism to prevent moisture loss? Or, is this curl and droop something that relates to the plant's ability to process sun? There is yet another theory. Because the leaves still retain moisture in the winter, a curled frozen leaf will thaw more slowly and therefore sustain less damage as it thaws. Most plant scientists agree with an explanation that something is happening with the shrub on a cellular level to prevent leaf damage. Whatever the explanation, we have to agree that the ability of plants to make it through the winter and gladden our hearts with beautiful blooms in the Spring and Summer is nothing short of incredible. So we, and the rhododedrons, wait for Spring. (photo by Mike Dunn)
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