By Faith Peppers
University of Georgia
“Most fruit and nut flower buds can tolerate temperatures slightly below freezing (1-2 degrees),” said David Berle, a University of Georgia horticulture professor. “But it all depends on the stage of development and the microclimate,” or local conditions.
Ice can actually work as an insulator for buds. “As long as it is raining, the ‘heat’ given off by water freezing actually protects flower buds to certain point, much like irrigation of the crops would do,” Berle explained.
But too many hours of hard freeze can spell doom for spring blooms, although it’s very hard to tell at this point what damage will be done, he said.
“If it gets to 20 degrees, it could be serious,” Berle said. “If it gets to 27 degrees, it is likely not to be a problem, but each site is different.”
The worst freezes come on cold, windy nights when a front is moving in and temperatures drop rapidly.
Some woody ornamentals like azaleas may survive the freeze. “Azaleas are not as far along as most fruit crops, and in a dormant stage they are fairly cold tolerant,” Berle said.
There isn’t much homeowners can do to protect fragile plants, which is why it is so important to use landscape plants that match the hardiness zone they live in.
“Landscape plants hardy for this area have a great capacity to make it through freezes and frosts,” Berle said. “Typically, it is only those actually blooming at the time for the freeze or frost that suffer.”
Mulching material like pine straw layered 2 to 4 inches thick can be effective to keep ice off tender buds and pansy blooms, but should be pushed back when temperatures rise to allow the soil to warm up.
“It’s kind of hard for homeowners to do anything about freezing plants,” Berle said. “Covering plants with fabric only provides a few degrees of protection, and then only if well-covered. Plastic works as well for a few degrees, but must be removed before the sun comes out and ‘bakes’ the plants underneath.”
Berle adds that most plants can endure frost better than freezes.
Frost occurs on a clear nights as heat radiates from surfaces to the sky. When the temperature drops below 32 degrees, water vapor freezes on surfaces like blades of grass, flower blooms and your car windshield.
Freezing, on the other hand, usually accompanies a cold front moving in with freezing temperatures, wind and sometimes rain.
For advice on protecting landscape plants from frost and freeze or a list of the best plants for your hardiness zone, contact your local UGA Cooperative Extension agent at 1-800-ASK-UGA1 or online at www.ugaextension.com.
(Faith Peppers is the director of public affairs with the University of Georgia College of Agricultural and Environmental Sciences.)