Cold Protection--READ

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VEGETABLES
Protecting Plants from Frost Using Plastic Jugs, Opaque Hot Caps
and Wall-O-Water
  Research done at Virginia Polytechnic Institute and State
University tested common cold weather protectors on tomato
plants. They found that plastic jugs (with the bottoms sliced
off, caps on at night, off during the day) retain heat poorly.
Soil temperature under the jugs decreases rapidly during the
evening.  They kept the air temperature about 1.8 degrees F
higher than the ambient air temperature for most of the night.
Wax-paper hot caps were a bit better, raising the air temperature
around the plants by as much as 2.7 degrees F above ambient
temperature. The Wall-O-Water maintained a nighttime temperature
around the plants as much as 5.4 degrees F warmer than the
outside air. It also slowed temperature decline around the plants
the most due to the heat retention of the water inside the Wall-
O-Water's walls.
  The opaque hot caps drastically reduced the amount of solar and
photosynthetic energy received by the plants underneath. Although
the hot cap plants eventually recovered and developed normally
later in the season, the number of fruits on the plants was about
half that of the unprotected control plants.
Fruits from the plastic jugs actually were five days behind the
uncovered plants. Plants capped by the Wall-O-Water and the wax
paper showed their first ripe fruit about 7 to 11 days earlier
than the uncovered ones, but early fruit were small.
     Results show that plant covers provide some protection from
cold temperatures and provide earlier small fruit. Perhaps, a
better choice is the use of floating row covers made of
polyethylene fabrics. This product provides 2 to 5 degrees of
freeze protection and allows water and sunlight to penetrate.
Planting at the proper time is easier and can be as productive a
gardening method. (GE)
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