The horticultural plants grown in Poland differ significantly in climatic requirements. These differences relate to the frost resistance of the aboveground parts and the roots, the necessary amount of heat during the growing season and the water content in the soil.
The resistance of plants to frost is a genetically determined feature, characteristic of particular species ; varieties. The apple tree is the most resistant to frost, and the grapevine, at least.
The frost resistance of fruit plants varies from late autumn to early spring.
It is intensifying since November, peaks in January, and then it decreases until spring. According to the data, peach shoots frozen in mid-December at -18 ° C, in late January at -26 ° C, and in March at -15 ° C. When the air temperature in winter rises above 0 ° C, trees and shrubs toughen up, that is, loss of frost resistance. Slow, lowering the temperature increases this endurance. On the other hand, rapid temperature drops after warming up cause trees and shrubs to freeze. It was like that in the year 1971, when it is after a longer warming in early March, at the end of the month the temperature had dropped to -20 ° C, causing the flower buds of most fruit plants to freeze.
