Mr. Carrol certainly found a way to make landscape dormancy sound romantic. However, there is nothing romantic about losing plants to frost damage!
In Maricopa County, the average first frost date varies from November 21st to December 12th. The average last frost date ranges from February 7th to April 3rd. It is important to protect your plants from frost damage. To do that, it is helpful to understand cold weather, how heat is transferred, how plants respond to cold, and how to care for plants that have been damaged by frost.
The sun warms the ground during the day. That much is pretty obvious. You have likely felt the warmth of the sun on your face when you step outside. Did you know that the heat radiates into the cool atmosphere during the night? If it is cloudy, the clouds will absorb and reflect the heat back to the earth. Clear nights present the greatest danger for frost because there are no clouds to radiate the heat back to the soil. There is also no wind to mix the ascending air with the descending air.
There are three ways that heat is transferred. These are conduction, convection, and radiation. When heat is transferred through direct contact, this is conduction. The transfer of heat by currents in gasses is convection. Radiation is the transfer of heat through the atmosphere.
Understanding how heat is transferred is helpful in knowing how to keep plants warm.
Plants react to cold temperatures by going into a dormancy state which makes the plant less susceptible to damage. This makes the plant “harden off.” If a freeze occurs and the plant has not been exposed to cold weather, it will not be dormant. This means that the damage will be more extensive. Damage can include death of dormant flower buds, dieback of plants, frost damage to shoots, flowers, and fruits.
Frost protection
“I wonder if the snow loves the trees and fields, that it kisses them so gently? And then it covers them up snug, you know, with a white quilt; and perhaps it says 'Go to sleep, darlings, till the summer comes again'.”
― Lewis Carroll, Alice's Adventures in Wonderland & Through the Looking-Glass