Frost damage can occur at any time between September and mid March.  Frost can cause the cell contents of plants to freeze.  Water expands when it freezes so frost can result in cells rupturing and dying.  Tree bark may split and develop cankers as a result of frost damage.  Buds can be damaged or killed from frost if late frosts occur in springtime.  Damage results in a reduced production of flowers and fruits.  In addition fruit itself can be damaged by frosts.  Smaller trees that are vulnerable to frost damage can be protected with horticultural fleece.