Woody plants and dynamics of late spring and early autumn frosts at Saint-Petersburg

Nowadays in the conditions of climate warming the duration between the last spring frosts and the first autumn frosts at Saint-Petersburg comparing with the middle of the XX century has enlarged for 18 days, from 156 till 174 days. At the beginning of the XXI this phenological interval continues to extend. In 1980-2000 comparing with 2001-2021 it has enlarged on 10 days. The spring frosts finish, beginning with the second phenostage of subseason "Thawing of Snow" till the second stage of subseason "Height of Spring", with prevalence in subseason "Reviving of Spring". The first autumn frosts may begin from the first stage of subseason "Golden Autumn" till "Before Winter", and more often in subseason "Deep Autumn". In the middle of XX century, at period which was named "the norm of the modern climate", the main results of arboriculture in the country were analyzed, the fundamental edition "Trees and shrubs of the USSR" (1949-1962) was published. And the possibilities of future culture of many exotic species of trees and shrubs were clarified for many years ahead. Apparently, the former data on levels of adaptation of woody plants need to be revised. In conditions of the modern climate late spring frosts and early autumn frosts does not show such negative influence on trees and shrubs as earlier. Nevertheless its influence should not be excluded.