Just wondering--I understand that a major determining factor
of assigning a growing zone is the lowest expected winter time
temperature. In what different way is a plant affected when the low temperature
is say, minus 10 F verses minus 20 F verses minus 30 F. It seems to me that at
some point, warmer than the example temperatures, that plant tissue would be
frozen completely and any lowering of the temperature would not make any
difference. What happens?
Along these same lines, here in zone 4 I am used to things
freezing up around December 1st and more or less staying that way until around
March 1st. We can also expect a protective layer of snow during that
time. The last three years we have had very little lasting snow
cover because of the many days above freezing and the accompanying warmer
nights. I have been following the advise for years to mulch certain plants
in the late fall to avoid winter damage from freeze/thaw cycles. So my next
question is: At what point can I expect damage on the general plant
population from all these unusual freeze/thaw cycles?