Trees and shrubs with a frozen root system

tree-casingTrees and shrubs with a frozen root system require stronger pruning, that a balance is kept between the damaged root system and the aboveground part. It consists in shortening all branches of Fr. 1 /3 or even half their length. On the other hand, frozen branches should be removed during the growing season, when they clearly die. Weakened plants should be watered abundantly and carefully combated diseases and pests, and feed them with nitrogen before and after flowering. Plants freeze more easily, which later stop growing, and their tissues are insufficiently lignified. This is favored by the late application of nitrogen fertilizers.
During snowy winters, the root system does not freeze. However, in snowless winters, it should be protected with a layer of manure, peat or a mound of earth. In areas with more harsh climates, it is better to plant trees on frost-resistant rootstocks.
The trees can be largely protected against freezing of trunks and limbs by whitewashing them with lime. The preparation of milk of lime consists in thoroughly mixing one shovel of lime in a bucket of water. Bleaching is best done in December and repeated in January, if the lime was washed off. On the other hand, the whitewashing of trees in March and April does not fulfill its function. Trunks of young trees can be wrapped with straw or other material protecting against the cold; then no bleaching is applied. Peaches and apricots are the most sensitive to frost. That is why trees of these species should be wrapped whole with straw or corrugated paper.