There is a method that farmers can apply against frost in when there is -4 and -5 degrees. Though they have different methods.
Freezing the flowers. In general, the flowers of fruit trees can hold up to -2 degrees -1 you did not know. If the air temperature is going to go down further, farmers water the trees and cover the flowers with ice and protect them. Although the outside temperature is -5 degrees, flowers with an ice pattern of no more than -1 degrees survive and continue to develop healthy. In a place where the air temperature is -20 degrees, it can be considered as the freezer -4 degrees.
Of course, as with everything, there is a limit to this method. With a rough calculation, you can survive weather conditions down to -5 degrees with zero damage by applying this method. Within -5 degrees, it means you will lose about 10% for 1 degree temperature.
Note: Everything has a chemical-free solution in nature. Ask for enough and believe.
