Reading Rhododendrons

What's the temperature outside?  That's a question all of us have asked our friends or family members at some point these past frigid weeks. It's the first thing we want to know waking up and probably the last thing we want to know before heading to bed. 

With so many outlets to access current temperatures at our fingertips, I actually did a double take the other day when my husband wanted to know the outside temperature and asked me "what are the rhododendrons doing?" 

"What are the what doing?" I asked.

"What are the rhododendrons doing?" he repeated himself.  "You can tell how cold it is by how tightly their leaves are curled up." 

Can a plant really tell the temperature? My husband, who majored in horticulture, says their leaves are a fairly accurate way to tell how cold it is outside, without stepping outdoors.

Now I know that rhododendron leaves curl up when it's cold. I'm not particularly fond of the plant myself.  I find the stark bush with it's stringy leaves unattractive year-round and it's flowering period in early summer woefully short.

But my husband likes them and our property has several bushes. One large bush sits right outside our kitchen windows, so I immediately looked down at it.

The leaves were curled up so tightly into themselves, they looked almost like long, green cigars. "They're pretty tightly closed."  I answered back.

My husband joined me at the window and examined the plant. "I would say it's about 26 degrees outside", he estimated.

I was now interested in testing his theory, so I turned on the television, turning to our local 24-hour news channel, which always shows the temperature in the lower right screen. It read 24 degrees, two degrees off from the rhododendron's reading.

I was impressed. As a former city dweller, the closest thing I had to an outdoor thermometer was looking out my apartment window to see what people were wearing, as they passed by on the street.

The process that causes rhododendrons to curl up is called "Thermotropism" and is believed to give the plant certain survival advantages under harsh conditions.

If the leaves are open, laying flat, that usually means above freezing temperatures.

If the leaves are curled in, then its just below freezing and if the leaves are really curled tighter, then the temperature is dropping even more.

Results may not be as accurate if the plant sits in the sun or out of the wind.

So far I haven't learned of another plant that can tell the temperature as closely as the rhododendron, if I do, maybe we'll re-plant.

For more, go to www.yourpotluck.com.