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.

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.

Daylily (Hemerocallis) is a perennial herbaceous plant widely used in landscape gardening. Daylilies are prized for their long term flowering mainly in late summer and low maintenance cultivation. According to flower spike height, the varieties are divided into runt, medium-growing and tall. The article contains the results of the study of 21 medium-growing daylily varieties’ terms of flowering in the botanic garden of the Volga region State University of Technology (Yoshkar-Ola, the Republic of Mari El). The research was conducted in 2015 - 2017. The calendar dates were converted into a continuous series. All varieties were classified as early, medium or late according to the terms of the beginning and the end of flowering and its duration. During three years of research, the earliest beginning of the phenological phase was registered in 2016, and the latest one  - in 2017. The early beginning and ending of flowering were typical for the varieties “Dr Regel” and “Royal Sovereign”. The late beginning of flowering was registered for the “Country Club” variety, and the late ending - for “Sandalwood”. Other varieties were classified as medium-term. The varieties “Royal Sovereign”, “Tejas”, and “Sugar Candy” are characterized by a short flowering period, while “Sandalwood” and “Derby Bound” - with a long one. It was established that the late-flowering varieties are characterized with a longer flowering period.

The article contains the results of the 2014 - 2018 phenology observation over 6 maple tree species (Acer L.) with natural habitats in North America. The objects of research were plants of the Botanical garden-Institute of VSUT: A. negundo, A. pensylvanicum, A. rubrum, A. saccharinum, A. saccharum, A. spicatum. The studied maples began growing at the end of April – the first decade of May and ended in October. The first, in the first decade of May, bloomed A. saccharinum and A. rubrum. Later blooming species were characterized by a longer flowering period, the latest and longest flowering within 20 days was observed in A. spicatum. Despite the different periods of flowering, the fruits of different species ripened relatively amicably, in the second half of September. The longest vegetation period was found in A. saccharinum (169±2.1 days), and this species is characterized by late autumn leaf blooming. The greatest period of autumn leaf blooming, more than a month, was characterized by A. spicatum. The studied species can be used in landscaping of the Mari El Republic settlements as part of an additional assortment, with the exception of A. negundo, which is a weed plant. Despite the similar timing of the passage of many phenophases, the variety of maples morphological features (shape and size of leaves, flowers and fruits, bark color, etc.) allows them to be used for decorative purposes. During the study period, the earliest passage of most phenophases was recorded in 2016, and the latest in 2017 and 2018.

Hazelnuts have an important nutritional value. Breeders have bred a number of varieties capable of forming high yields in the conditions of the Central part of Russia. The purpose of this study was to analyze the fruit indicators and the reproduction potential of hazelnut variety 'Academic Yablokov' in the Mari El Republic. The advantage of this variety is large fruits and purple leaf color. The studies were conducted in 2020 and 2021 in the Botanical Garden-Institute of Volga State University of Technology (Yoshkar-Ola). The study showed that nuts have the mass of 2.0-2.4 g, the length and diameter of 2.4-2.6 and 1.4–1.6 cm, respectively. In the abnormally hot and dry conditions of 2021, the variety fruits were lighter and smaller compared to the excessively humid conditions of 2020. But the seed quality remained relatively high in both years of the study (82-84%). Sowing nuts using peat and sand as substrates revealed different soil germination of seeds in the experimental variants. The smallest number of seedlings was obtained in the peat variant (26%). The highest germination rate was established in the control variant (43%), but in the future the seedlings turned out to be in less favorable conditions for growth – by autumn they had the smallest height, diameter of the root neck, and number of lateral shoots. The seedlings in the variant with sand had the greatest height and length of the root system.