Re: Trevisia palmata hardiness-refutation.
----- Original Message -----
From: "Prof. Michael Barclay.
> Dear List, and Especially the Crazy Envelope Pushers,
April 3,
> 2001
> Cusonia paniculata has been on my dry slope for 22
years. It too
> became a dried
> pool of goup in 1990---five day freeze---temps. 19F,
22F, 23F, 27F,
> 33F with the
> ground solidly frozen down three feet and no thaw until
the fourth day
> when it hit
> 45F in the mid afternoon.
Hello Michael,
You have written before about the ground being frozen down
3 feet. I don't think this is possible in five days of
"mild" freezing temps. I can't recall now but I think you
need something like one degree of frost x one day for 100
days or so to freeze about a foot.
In your 5 days, assuming you had 30 degrees of frost over
5 days, I doubt it froze 6 inches even. You just didn't
have enough frost degree days.
I spent 16 years in the high Arctic regions of Canada
where the surface soil thawed and froze each year on top
of the permafrost. It took a number of fall freezes to
freeze the surface. Peat bog areas are the last to freeze
due to the great insulating quality of peat.
Here on Vancouver Island where we haven't had a freeze
much over a week for some years, the soil only freezes on
the top, sparing the roots of some fairly tender plants.
Most things can be protected with a layer of mulch. In
past years of prolonged freezes of two to five weeks, the
frost depth doesn't even reach our waterline which is
buried at only 1 - 2 feet over a distance of 170 feet.
It is repeated freezing and thawing which causes most
damage to plants as well as dry cold without
precipitation. More plants succumb to dry cold and wind
than frozen roots. I have yet to lose a rhododendron, for
example, in 30 years here due to freezing. I grow nearly
300 including some fairly tender ones.
I wanted to bring this up the last time you mentioned your
'big freeze'.
I enjoy your postings very much and your infectious love
of your plants.
Diane Pertson
Otter Point Haven
Vancouver Island
(where it varies from Zone 7 to 9 over 30 years)
