Representatives of the genus Hydrangea L. are ornamental flowering shrubs. Due to insufficient knowledge of bioecological features, species and varieties of representatives of the genus Hydrangea in the Middle Urals are still rarely used. The objects of the study are 14 varieties and species of the genus Hydrangea, which were planted in the collection of the Department of Plant Introduction and Acclimatization of the UdmFIC, Ural Branch of the Russian Academy of Sciences, Izhevsk, in 2017. The aim of the research is to study the bioecological features of new species and varieties of representatives of the genus Hydrangea for the prospects of introduction in the conditions of the Middle Urals. The paper presents the results of phenological observations in the period 2019-2021 for three main phases for flowering shrubs: the beginning of vegetation, the beginning and the end of flowering. The characteristic of climatic conditions of this research period is presented. Abnormal periods for plant development (lack of moisture against the background of high daytime temperatures, cool May and June) and their effect on decorative during the growing season in the conditions of the Middle Urals and their influence on the decorative properties of the studied plants. It is noted that the beginning of vegetation of representatives of the genus Hydrangea depends on the transition of the average daily temperature above +10 оC. The lack of moisture during the growing season has a negative effect on the development of plants and on the quality of flowering. An important property for flowering shrubs is the duration of flowering. The longest total flowering over three years of observations is more than 300 days in H. paniculata Weems Ed, H. petiolaris Petiolaris, H. arborescens Anabel. For more than 200 days in three years, almost all the studied varieties of H. paniculata bloomed, except for the Pink Diamond and H. Serrata Bluebird varieties. According to the results of research (2019-2021), 8 representatives of the genus Hydrangea were identified as promising (group I, II) for green construction in the cities of the Middle Urals, who scored more than 75 points according to the integral assessment of the prospects of introduction and have good decorative properties: H. paniculata Lime Light, Pinkie Winky, Diamond Runge, Weems Red, Vanilla Frise; H. serrata Bluebird; H. arborescens; H. petiolaris Petiolaris. The studied varieties of H. macrophylla Nikko Blue, Teller Blue, Tivoli and H. quercifoli Applose are included in the group of less promising and unpromising ones, the use of which in landscaping is possible with the use of shelter for the winter.