Frost can affect many plants, and is particularly damaging to tender new growth and blossom in the spring. Damage is seen by the blackening of parts of the plant, particularly on new growth. Shoots may be scorched at the tips and flowers can be killed outright. The damage is caused by the formation of ice crystals in the plant tissue that pierces the plant cell walls.
Ground frost occurs when the temperature falls below freezing point and air frost occurs when the temperature of the air falls below freezing point. Repeated freezing and thawing, or very rapid thawing, can be particularly damaging to plants.
Once the temperature has fallen below freezing, a strong wind can make frost more damaging (wind chill). Cold winds remove moisture from evergreen foliage more quickly than it can be replenished by the roots, which can cause leaf browning, particularly at the tips and margins.