CHARLOTTE, N.C. — Much of the Charlotte region is bracing for freezing temperatures Wednesday morning, threatening to foil overzealous gardeners who planted a little too early.
A Frost Advisory is in effect from 2 a.m. to 9 a.m. Wednesday, meaning tender plants could be at risk. People looking to protect those outdoor plants can bring them indoors or cover them with cloth.
Another trick some green thumbs use is spraying plants with water ahead of the freeze, but does that really work? And if so, how?
OUR SOURCES
Question
Does spraying plants with water ahead of a freeze help protect them from injury?
Answer
Yes, while not a solution for every freezing situation, sprinklers can help protect plants from freezing injury.
In his walkthrough of the proper process, Longstroth writes, "Sprinklers used for irrigation do not protect below 23-24 degrees F," noting that in some cases, spraying water can cause more harm to the plant.
Question
Does spraying water protect plants by creating an insulating layer?
Answer
No, the protection does not come from "insulating" ice. Panovich said that is a common misconception about the sprinkler trick.
While many people assume the freezing water around the plant creates a layer of insulation, Panovich notes that it is the freezing process itself that keeps the plant warm.
The root of the trick's protection is a concept called "latent heat of fusion." When the water on the plant starts to freeze, it releases heat (a necessary process to turn water into ice), and that heat helps protect the plant.
Panovich said there is also some protection gained when the above-freezing water is soaked up through the roots, keeping the plant warmer from the inside.
Question
Since the sprinkler trick only works in certain scenarios, can people in the Charlotte region use it during Wednesday's freeze?
Answer
Yes, Panovich said the short duration of the frost/freeze, coupled with the projected lows, sets up people using the sprinkler trick for better success.
Temperatures Wednesday will bottom out in the mid-30s in Charlotte and surrounding areas, and they are expected to bounce back to the 70s later that day.
Contact Vanessa Ruffes at vruffes@wcnc.com and follow her on Facebook, Twitter and Instagram. Contact Brad Panovich at bpanovich@wcnc.com or follow him on Facebook, Twitter and Instagram.
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