Hanging Christmas lights inside evergreen, broad-leaf trees is one way homeowners can ward off freeze damage during extremely cold nights, according to University of California Cooperative Extension farm advisor Mark Freeman.

"Hanging the lights inside the tree canopy, especially in citrus trees, and leaving them on all night may create enough warmth to protect trees from damage," Freeman said.

Deciduous trees and evergreen conifers generally are not harmed by the freezing temperatures.

Wetting the soil under trees and shrubs during the day will also help prevent damage.

"Compared to the air temperature, the water is warm. As the water cools from 60 degrees or so to freezing, it gives off warmth that protects the trees," Freeman said.

However, he cautions, homeowners should avoid wetting the tree or shrub's foliage unless they will continue irrigating through the night. If the foliage is wet, the water freezes and dips down to the air temperature, which can damage the plant.

Throwing a sheet or light blanket over trees and shrubs will also shroud them from cold.

Freeman, who conducts research and advises commercial citrus and almond growers, said he feels hopeful the freeze of 1998 will not be as devastating as the 1990 freeze.

"In 1990, we had clear skies and a week of freezing temperatures, sometimes continuing through the night and day," he said. "This time we've had three days of significantly cold temperatures and a warmer inversion layer that allows growers to mix the air with wind machines to protect their trees and fruit."

However, he said the extent of the damage won't be known for at least several days.

For more information contact Mark Freeman at (559) 465-7265, or e-mail mwfreeman@ucdavis.edu.

Jeannette Warnert
Public Information Representative
Ag and Natural Resources
UC Center
550 E. Shaw Avenue
Fresno, CA 93710