[Arid_gardener] Re: Frost Protection Publication

[Olin Miller]

University of Arizona Publication "AZ1002 Frost Protection " at
http://cals.arizona.edu/pubs/garden/az1002.pdf
also has suggestions that may be helpful.

Olin Miller, Master Gardener Volunteer
U of A Cooperative Extension, Maricopa County AZ
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----- Original Message ----- 
From: "Dick" <rkgross3 at cox.net>
To: "Carl R King" <crk12 at juno.com>
Sent: Sunday, November 25, 2007 12:36 PM
Subject: Re: Re: [Arid_gardener] Fwd: Navel orange tree


Carl, I have tried several tricks or techniques to protect plants from frost
damage when the weather man issues warning but only then. It is too much
trouble otherwise. I have not always been successful, however. I have used
Xmas lights on many ocassions and found the method effective but would be
hard pressed to prove it.

A standard practice in California some years ago was to flood basins. As
water freezes it releases heat and it apparently works except that it causes
a muddy mess and, if several days of frost strike, the duration is itself a
problem.

One year I used an oscillating water sprinkler that covered nearly
everything in my yard. I awoke early the next morning to find that the
sprinkler had siezed but my citrus was coated entirely with a coat of ice a
quarter of an inch deep in some places. Assuming everything was lost, I was
sick. But, to my utter amazement, after everything thawed, not a leaf was
damaged. The ice provided absolute protection. That phenomenon can be easily
explained by physics but the logic escapes me at this moment.

I have used Christmas tree lights, heat lamps,  kerosene  pots and any other
heat source I could dream up to create air circulation. I don't believe it
was the heat alone.  The friction caused by air molecules against one
another and the friction it causes in foliage generates heat and freezing is
unlikely under these conditions unless it is a hard freeze of long duration
like two or three hours for which, in my opinion, there is no effective
protection except a heated greenhouse. Every severe frost damage I have
experienced in Phoenix and on the West Coast occurred when the air was dead
still. I would assume similar circumstances would prevail in any
Mediterranean-like climate.

The most effective protection for me has been a large, industrial,
oscillating fan on a pedastal. It covers my entire yard with an air flow. In
California, I once observed that it would never freeze when there was a
breeze and a fan creates a current. California citrus growers have for years
used airplane propellers positioned above the canopy to circulate air when
the orchard was threatened by frost. Years ago in Chula Vista, Ca., the
early morning air would be black with soot from diesel and stove oil burners
in orchards.

I have used bed sheets effectively  but, on other peoples advice avoid
plastic covers unless you can prevent any contact with foliage like in a
greenhouse.

Small plants are effectively protected with sheets but most advocates insist
that coverage should be all the way to the ground.

Dick Gross, MVG, U of A
Maricopa County Cooperative Extension
  ----- Original Message ----- 
  From: Carl R King
  To: rkgross3 at cox.net
  Sent: Sunday, November 25, 2007 7:26 AM
  Subject: Re: Re: [Arid_gardener] Fwd: Navel orange tree


  Hi Dick,

  I've written you asking about my navel orange tree and how to get the then
36 yr old tree to bear fruit again.  I'm happy to report it has many oranges
as I write.

  My question concerns keeping shrubs safe from freezing.  Would placing
standard-sized outdoor Xmas lites on it generate enough heat to ward off the
freeze?  I purchased these shrub after assurances they could withstand
freezing.  Last years freeze did severe damage although you wouldn't know it
today.  I'm hoping the heat the bulbs put out would be enough to offset the
cold.

  Thanks again for being there.

  Carl


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