AREN’T PLANTS FASCINATING 

Now don’t panic just yet.  While I realize it has been colder than hell, we have not even come close to the cataclysmic winter of last year.  In fact, we are still just perking along at a typical Zone 8 winter which means winter lows in the 10-20’s.  When I moved up here twenty years ago we were classified as a Zone 7 area which translated into winter lows of 0-10 degrees.  I can think of only a half dozen times over these past 20 years where the temps have actually gone into the single digits.  So far this year we are still in the teens.

By the time you read this column we are supposed to be back into a warming trend with gray and wet weather and lows in the 30-40’s and hopefully no more frozen plants and hoses and soil.  If that hasn’t occurred and we are still in the teens at night and at or below freezing during the day then clearly we will all see some winter kill in our gardens.  It’s not just how cold it gets be also how long it stays cold that determines how well our plants can survive.  Last year on December 20^th it dropped down to 7 degrees here at the nursery and that was on top of about 2 weeks of multiple snows and below freezing temps.  All combined, it was just too much stress for many of our plants.

If you can get past the anxiety of wondering what is alive or dead then it is kind of interesting to look at how plants behave in freezing temperatures.  Rhodies provide us with one of the clearest examples of coping skills for broadleaf evergreens.  As the mercury drops the leaves on rhodies will start to droop and begin to roll in on themselves.  They can roll so tight that they will look like little cigars on a stick.  What is happening here is that the plant is trying to minimize its surface area which in turn reduces its exposure to the elements.  This action is equivalent to us rolling up into a ball to conserve our body heat.  Because rhodies have woody stems that can’t curl the best they can do is to roll their leaves.  Some soft-tissued perennials can actually curl their entire form down tight to the ground. 

For warm blooded creatures like us, protection from the cold is mostly about conserving body heat.  For plants it is more about conserving moisture.  The leaf rolling behavior protects the stomata which are the orifices on the leaf through which moisture is released.  You can see this same action in the summer on grasses when there is a drought.  The blades of grass will roll up tight just like a rhodie does in the winter.  And believe it or not, cactus, while not having what we think of as leaves, can make their fleshy stems accordion in so that the folds of the stem are protected from the drying sun.

It’s times like these that I wish I had a time-lapsed camera to record these processes.  Maybe it is just the plant nerd in me, but I find these techniques of Nature fascinating.  Last winter I noticed that my 20 foot tall weeping slender purple beech had no leader.  Instead there were to completely horizontal branches at the top where there should have been something vertical.  I couldn’t help but wonder what would happen as this tree started to grow this spring so I kept a close eye on it all year long and sure enough, as the season progressed the horizontal limb on the east side gradually lifted itself up and is now about 45-50 degrees of vertical.  The other horizontal limb dropped down in the opposite direction and by this time next year my tree will once again have a normal vertical leader.  Evidently this drama has been going on every year, I just never noticed it before. 

The problem is that this process happens so slowly that we are oblivious to it.  By now I can no longer conger up the image of those two horizontal branches from last winter.  I should have taken a photo every month and recorded the whole process but who can remember to do that?  Instead, I have found a new product on the market called the Plant Cam which will do all this stuff automatically for me.  The Plant Cam (there is also a Bird Cam) is an all-weather digital camera that you can program to take pictures at various intervals.  You set the intervals and then go off and do your own thing and let the camera do the rest.  When you are done you simply remove the disc and download it to your computer.  We will have them for sale this spring but if you want to get one this year for the plant nerd in your life then you can order them online. 

So instead for worrying over the potential damage this winter could be causing I challenge you to observe and learn to appreciate the amazing adaptive behavior of plants.  They are simply fascinating.