From late autumn to early spring, trees and plants risk enduring freezing temperatures which can cause damage to the most fragile specimens. In this article, we outline the causes & symptoms of frost damage. In another article, we will see how to protect and prevent frost damage.
Symptoms of frost damage
For most plants, frost damage is immediately apparent following freezing temperatures. But for trees, the damage is not always obvious and can take several months to appear. Here are a few things you can look out for:
- Hard winter frost can cause leaves of evergreens to turn brown and may eventually lead to the death of the tree.
- Spring frosts can damage young growth. Look for pale brown patches between leaf veins. The leaves at the top and edges are particularly exposed.
- Blossoms and young fruits can be at risk during spring frosts. Damage to blossoms can prevent fruits from forming and a corky layer can form of the flower end of young fruits.
- The first frosts of autumn can blacken the leaves of tender perennials. Stems usually then collapse.
- Prolonged periods of frost may cause spotting on the leaves of some shrubs. Certain foliage can present early symptoms of frost damage. Leaves can appear water-soaked and dark green, eventually turning black.
Causes of frost damage
There are two types of frost: ground frost and air frost, both occurring when the temperature (of the ground or air) falls below 0˚c. Freezing temperatures means the water contained in the tree or plant cells freeze, causing dehydration that can lead to the death of the tree or plant. Repeated freezing and thawing can particularly be damaging.
Newly planted and young plants are more at risk of frost damage. Tender plants can usually survive better winter when they are planted in a sunny location, sheltered from the wind. New wood is then ripened by the sun, making it more resistant.