In a previous post I discussed wrapping a tree to keep it warm. I looked at the physics and concluded that wrapping a tree, or any other plant, does not keep it warm. I had never seen any data to support this position, but it certainly follows basic laws of physics. I decided that this winter I would measure the temperature under a wrapped evergreen.
I have a yew that the deer eat every winter unless I wrap it. So I decided to use this tree as my test subject. It is located near the house, on the northwest side. The tree is wrapped in several layers of burlap down to about 6 inches from the ground. During the winter I went out with a lab grade thermometer to measure the temperature both in the air and under the burlap wrap.
I tested this on cool days, sunny days, cloudy days, windy days and even on our record breaking -30 C day.
The temperature of the air under the wrap and outside the wrap were exactly the same under all of these conditions. It is good to know that the laws of physics still hold true!
What About the Wind Chill Factor?
The wind chill factor is something we humans use to express how we feel. On a windy day, we feel colder because the wind is removing body heat from us.
In winter, plants have almost no body heat. The temperature of the plant is the same as the air temperature. Wind does not decrease the temperature of the air or the plant.
The wind chill factor has nothing to do with plants.
Are Wrapped Trees Warmer?
Wrapping trees will not keep them warm. The wrapping may reduce moisture loss which can be beneficial in some cases–this is discussed in more detail in Should Plants be Wrapped in Winter.
Do Styrofoam rose cones work? Find out in a new post called Styrofoam Cones – Do They Keep Roses Warm in Winter?