In article ,
"Denis Mitchel" wrote:

Does the temperature have to be at or below freezing for frost to form on
plants?

Thanks

Below freezing, because the plant(s) will carry over some heat from the
day and the ground, if dry, will be reflecting some heat as well. This
heat must be removed before freezing can occur. As Bill alluded to, as
long as your making ice (there is water to freeze) the ice will remain
at 32F (0C).
--

- Billy
"For the first time in the history of the world, every human being is
now subjected to contact with dangerous chemicals, from the moment of
conception until death." - Rachel Carson

http://www.youtube.com/watch?v=WI29wVQN8Go

http://www.haaretz.com/hasen/spages/1072040.html