This winter’s first REALLY cold temperatures are predicted for the North Coast next week, a high of 12 degrees F (!) for Tuesday. Time again to talk about the Rhododendron Thermometer. The illustration above shows leaf droop as temperatures drop.
Do you have Rhody in your yard? They are in many yards in Lake and surrounding counties. Holden Arboretum has the Helen S. Layer Garden which contains over 1,200 rhododendron plants. They are beautiful spring bloomers. I am lucky to have two, one on my patio and one in front of my house by my garage.
On the coldest of winter days it looks like this:
I was pretty freaked out the first time I saw this - I was afraid I had neglected to cover it, to protect it from the cold. But after doing some research I found that this phenomenon is called a “thermotropic” reaction and is a natural reaction that helps prevent dehydration under conditions of extreme stress.
In this photo it is covered with snow but it’s not cold enough for the leaves to curl. However they are drooping.
It’s a very accurate temperature indicator Next week, when I look outside and the leaves look like this, I’ll put on two pairs of gloves!