Thanks, Trace. In California they used to use wind machines and orchard heaters (fuel oil fired); now virtually everyone uses sprinklers. Most well water is about 60F; so that alone helps a lot, plus the added heat given up when the water turns to ice; but if you have too long a cold spell the trees can suffer from too much water. In such cases a lot of groves use helicopters to stir the air; but all of these only protect for a few degrees, not for hard freezes, or prolonged cold.

Thank for knowledful input john.
Trace