Field of Science

Any good outcomes of winter cold?

It's been 35 years since the upper midwest has had a winter this cold.  Since December began there have been 20 days (nights) where the temperature has been below zero, and for those of you using a sensible C scale, water freezes at 32 on the F scale, so below zero is more than 32 F below freezing.  As the Phactor wonders how some of his semi-hardy, maybe-not-quite-zone 5 plants will do, a neighbor asked if anything good could come of such cold?  Last winter there may not have been any days with below zero temperatures, and the frequency of really cold winters has been decreasing (yes, as expected if the climate is warming).  Well, among the good possible outcomes might be if the emerald ash borer proves to be not so winter hardy.  Wouldn't it be great if a really cold winter knocked out the population!  Wow, that would be great. Some other insect populations might get reduced for a while too like the Japanese beetle, but all the snow cover this year may insulate those things that overwinter in the ground from the cold.  Same is true for some of the low-growing shrubs and other perennials. Snow is a great insulator.  So all we can do is hope for the best.  For example, the aerial portions of our Vitex are not winter hardy at these temperatures, but the basal portions will survive and resprout, so the dead upper portions must just be pruned off.  The last few mild winters had allowed it to become a 2.5 m tree, so for 2014 it will have to start over. 

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