Freeze damage to plants can be due to damage caused by ice crystals (I love Alton Brown's example of a plastic bag of water with shards of glass as the ice crystals). It can also be due to dehydration, with ice crystals growing by pulling water from the cells.

Plants that grow in cold climates have different strategies for dealing with this. Some use sugars or special proteins as anti-freeze for their cells. Some use a process known as vitrification, using chemicals to cause the water to freeze without forming crystals. That prevents the expansion and sharp crystals that cause damage.

Others use supercooling by controlling substances that could serve as nucleation points. Supercooling can sometimes be seen when bottled water is put in the freezer. If there are no impurities or bubbles to act as nucleation points, the water may remain liquid at subfreezing temperatures, but will freeze very quickly when the bottle is opened.