Re: winter damage/zones
Hank,
here in this area(zone 5/6 high desert ) freeze and thaws with no snow cover are commonplace,moreso in the last few yrs.
El Nino now La Nina have kept us much too warm but with periodic heavy freezes..Since we deal with this frequently here can tell you the biggest threat is HEAVING which of course causes root damage and potential death .Mulching to keep soil temps more even is very helpful if not imperative for some plantings.
Older well established (trees,shrubs etc.) deep rooters are not so subject to this sort of harm..But shallow rooted perennials,bulbs can be (I frequently find tulip bulbs on the surface after a winter of heaving forced them up)..
However since you have been experiencing this for several years and you have not sustained any long term damage I would say just keep doing what your doing..Living in these conditions now for over 10yrs I can honestly say if the plants are truly hardy and the ones requiring mulch were,I have not noticed any more damage here than where I lived up north where snow cover is the rule....
As to your question about -10verses-20temps and why it should make a difference since frozen is frozen ,well my take on it is it has everything to do with the <depth>of freezing in the soil.The longer/colder the temps the deeper the freeze.The roots being the life line to the plant if they freeze out goodby plant..Hence we cant winter over exposed container plants..There is heat coming from well below the surface which helps moderate the soil temps as well, add snow cover and your (hardy)plants are pretty safe.Its a fascinating subject which I too still ponder,my explaination's crude but I hope fairly accurate. I have
many zone 7 plants which survive due I'm sure to placement (foundations,etc)and the fact that the soil doesnt freeze that deeply there..
Upper growth of shrubs etc.that would have been protected via snow cover can and do suffer dissecation,freeze burn but dont generally die,spring pruning of the areas of damage tends to be the only measure required..Last thought,mulching also discourages premature growth ,due to abnormally high winter temps,many plants that are coaxed(their spring growth is tied to temperatures rather than light lengths) into this false 'Spring'can be harmed but sadly nothing I know to do about it beyond mulching..
Interesting note every year the Apricot trees come into bloom shortly following our first real warm weather in the day time(nites fall below freezing almost nightly for many weeks in the Spring)..Depending on how the weather goes it can completely wipe out all the blossoms =no fruit..I have used sprinklers,etc.but the best one I ever heard was a man who bought huge blocks of ice which he placed all around the root zone..Short of the story :He had Apricots while no one else did in his area..Lot of hassle but goes to show what you can conjure up if you have the where with all..Hope this helped you some.
Connie
Hank Zumach wrote:
> <<<< So my next question is: At what point can I expect damage on the general plant population from all these unusual freeze/thaw cycles?
>
> Hank Zumach
> Stoddard, WI
> zone 4
