Why Rhododendron’s Leaves Curl in Winter
I was wondering what I would write about this month when I noticed the rhododendron in my front landscape bed. Have you noticed and wondered why your rhododendrons curl up their leaves in the winter? I thought this might be a great thing to write about and explain.
As the temperature drops in the winter months, we’re fortunate enough to be able to put on winter coats, hats, scarfs and gloves to keep warm. Our outdoor plants though have to fend for themselves in the cold, under snow and ice, withstanding harsh winter winds. As the soil freezes and it becomes more difficult for water uptake through their root systems, and above ground as the cold, dry winter air begins to sap moisture from their leaves, rhododendrons (as well as other plants) take measures to conserve their moisture.
As you probably learned in biology, plants take up moisture through their root systems and transport it upward through the plant to the trunk, branches, stems and leaves. Water is released through the leaf stomata located on the underside of the leaf. As it releases water, more comes up through the plant to that same stomata.
When the plant is stressed from the winter weather causing it to release more water than it can take up, the plant will close its stomata and live on reserves until the weather warms up again. This is what causes the leaves to look curled! When the weather warms up and “water can flow again”, the stomata will reopen and the leaves will unroll. Photosynthesizing will then resume and our beautiful rhododendron will grace us with another season of spectacular blooms!