The cytoplasm of a plant cell is a watery fluid that fills up the cell. When water freezes to become a solid, it expands. This is why if you place a glass bottle filled with water in the freezer, it will break! Ice crystals formed at freezing temperatures can damage cell membranes. Together, this can cause plant cells to burst. If that wasn’t challenging enough, if the fluid around cells freeze, then the cells also dehydrate!
So, what about evergreen plants? Evergreen plants keep their foliage throughout the year, but their leaves and needles have a thick, waxy coatings to reduce water loss and maintain cell structure.
Some plants have special physiological adaptations to combat freezing temperatures, where they can activate a special protein called CBF. This causes a chain reaction of many other proteins being formed which work like anti-freeze in cars.