Using Sprinklers to Protect Blueberries from Spring Freezes
Many blueberry growers use sprinkler systems to protect blueberry flowers from spring freezes. Sprinklers are very effective under certain circumstances but can increase injury if used at the wrong time. Sprinklers used for irrigation do not protect below 23-24oF. If the system fails due to cold or wind the blueberries can get colder than in areas with no sprinkling. When you use sprinklers to prevent freezing injury, you are using the energy that water releases when it freezes, changing from a liquid to a solid, to keep the temperature in the ice at the freezing point 32oF. As long as you keep the ice WET, the ice temperature will stay at 32oF. If the ice dries out and water evaporates from the ice, it will chill the plant down colder than the air temperature as the ice evaporates.