You know it is cold outside when the melt off the roof is frozen coming out of the downspout. This morning it hit a low of 12 F and it is likely to get even colder later in the evening. One of nature’s thermometers that can tell you an approximate temperature is the rhododendron. There is no agreement to why this happens but as it gets colder and colder, the leaves curl and droop more and more. The following three pictures are of individual leaf clusters at 14, 26 and 36 F, respectively. As you can see, there is quite a difference in their shapes.
