The research was carried out at the Department of Fruit Crops of the Educational, Scientific and Production Center of Horticulture and Vegetable Crops named after V.I. Edelstein of the Russian State Agrarian University – Moscow Timiryazev Agricultural Academy in Moscow in 2021–2023. Flowering and fruiting of Juglans regia L. were evaluated during three years. It was found that J. regia plants with the lateral type of fruiting, which is characterized by the formation of female flowers in most axillary buds of the current year’s growth, have a high adaptive potential. The identification of the features of J. regia flowering phenology taking into account the peculiarities of the natural and climatic character allows to establish the best forms and determine the most optimal temperature conditions. The evaluation of the phenological phases showed significant differences between the J. regia cultivars in terms of the onset and duration of the phenological phases. A significant factor in reducing fruit set is systematic damage to male and female flowers and shoots by recurrent frost. The highest resistance to recurrent frost was observed in a number of forms with late leaf shooting: 1.26KSK. Unequal blooming of male and female flowers was revealed, the phenomenon of protogyny was observed in 70% of the studied forms, while the difference in blooming of male and female flowers ranged from 1 to 10 days. Fruits have a high amplitude of variability. The study showed that the shape and size of the fruit are constant on one plant.