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Protect Plants From Extreme Temperatures
MISSISSIPPI STATE -- Mississippi plants that survived the 100-plus temperatures last summer have new challenges arriving with winter's extremely cold days and nights.
Norman Winter, horticulture specialist with the Mississippi State University Extension Service, said most of the cold temperatures have been somewhat typical for the state and not as threatening for landscape plants.
"The cool, clear nights have been a big factor in increasing our fall colors, but they also produce frost," Winter said. "Clouds form near the ground and trap some warmer temperatures nearest the ground. People can help even more by adding a tall layer of pine straw, a box or blanket over some of the less durable plants."
Plants that are grown north of the zone they are recommended for will be at the greatest risk.
"The location of tender plants is critical for their survival outside. Plants growing next to a south wall or under the roof overhang can receive the needed protection from the cold," Winter said. "There are some locations, such as low-lying areas, that will increase the risk."
Large appliance boxes are good sources of protection, but today's gardeners have additional options that were not available for previous generations.
"Even before the deep freeze is predicted, people can prepare temporary greenhouse-like structures made with PVC pipe and covered with plastic or floating row cover in a matter of minutes, not hours," Winter said. "Run cords with electric lights under boxes or other structures for a few more degrees of warmth."
For the more serious freezes in the low-teens or colder, Winter said plants may need more than a cover. Bubble wrap is one material that has shown insulating potential.
"Wrap trunks of plants like palms and cycads to provide several degrees of protection in a vital area. When temperatures approach zero, a lot more protection may be needed," he said.
Southern Indica azaleas like Formosa, G.G. Gerbing and Pride of Mobile are hardy down to around 10 degrees. Camellia japonicas can endure a brief drop near zero but will need protection if cold last for an extended period of time. Sago palms (or cycads), windmill palms, and cabbage palms may need wrapping or covering if possible when temperatures fall below 15.
Winter warned that shrubs still under drought stress will be much more vulnerable to the cold.
"The late summer drought is going to take a toll on many of our landscape plants. Protecting the survivors or stragglers from killing freezes seems like the least we could do," Winter said.