Question: During the cold winter months, when temperatures dip well below freezing, what prevents trees (and shrubs) from turning into a giant icicle?
Trees basically have three ways of protecting themselves from freezing temperatures.
Most trees remove water from their tissues to enter a dehydrated or dormant state for the winter. That way, there is less water to freeze and expand.
Some trees produce more sugars in their sap to increase its “antifreeze” capability (the more sugar in the sap, the less likely it is to freeze). Maples do this and that’s why you get sugar-rich sap flowing at the end of winter which becomes maple syrup.
Some trees use super cooling. This allows a tree to keep water in the trunk even at below freezing temperatures without the water freezing. It does this by not allowing ice crystals to start forming in the sap. How? By adding pressure which, in turn, doesn’t let the molecules expand and form ice crystals.