Abstract: Species of the genus Philadelphus L. (mock orange) are among the most popular ornamental shrubs. They are valued for low maintenance, abundant flowering, exceptional aroma of flowers and a prolonged flowering period during high summer, by when many shrubs already fade. The results of phenological observations of 2018-2020 are presented in the article. The objects of the research were the plants of 8 cultivars of mock orange selected by N. K. Vekhov in the Botanical Garden-Institute of VSUT (Yoshkar-Ola, Mari El Republic). The vegetation of plants lasts from the beginning of May to the end of September and has a duration of 177-189 days.  The 'Airborne force' (Vozdushny desant) cultivar was characterized by the longest growing season.  The full leafing occurred in the first decade of June, the growth of scions ended in the first half of August. Flowering began in the third decade of June and lasted on average for 13-28 days. The cultivar 'Vosdushny Desant' has the earliest beginning of flowering, 'Arktika' has the latest one. The plants of 'Elbrus' were characterized by the longest flowering, 'Yunnat' – by the shortest one. There was no connection between the duration of flowering and the structure of flowers.

Abstract: Deutzia is an ornamental flowering shrub valued for its abundant long-term flowering and the elegance of flowers shape. The research objects are the plants of 3 species and 1 variety of Deutzia in the Botanic Garden-Institute of VSUT (Yoshkar-Ola, Mari El Republic). Plants aged from 38 to 45 years grow in the exhibition “Fruticetum”. The study was conducted in 2015-2019. The height and diameter of plants crowns, their winter hardiness for the period from 1981 to 2019, the morphometric indicators of leaves and inflorescences, the possibility of vegetative propagation by herbaceous cuttings, and the size of annual plants were studied. According to the study results, the most hardy is Deutzia of Amur, which forms the highest shrubs. The long-leaved Deutzia has the longest leaf blades, Deutzia scabra ‘Plena’ has the smallest leaves. The long-leaved Deutzia has the largest inflorescences, Deutzia of Amur and Deutzia scabra ‘Plena’ have the smallest ones. Deutzia magnifica and Deutzia scabra ‘Plena’ have ornamentality advantage over other species due to the double flowers. For the maximum display of ornamental qualities, the plants need a successful overwintering. The greatest ability to reproduce by herbaceous cuttings is noted for Deutzia scabra ‘Plena’. The results of this study are important for the Deutzia application in the garden and park construction. In the landscaping of the republic settlements Deutzia is recommended for the target assortment.