Assessment of modern garden rose cultivars in the rosarium of Peter The Great botanical garden

Modern garden roses - shrub roses are of particular interest for landscape design, having high winter hardiness, disease resistance and unpretentiousness in care. Their popularity is associated with high decorative qualities and environmental plasticity, which allows them to be used in various compositions. The article presents data on assessing the winter hardiness and decorative properties of modern collection cultivars of garden roses in the conditions of St. Petersburg. The research was carried out in 2020-2023 in the rose garden of the Peter the Great Botanical Garden BIN RAS. The objects of research were 10 cultivars of semi-climbing garden hybrid roses (shrubs). When carrying out the experimental work, phenological observations were carried out, according to the methodology for botanical gardens for phenological observations of re-blooming roses, as well as biometric observations. Winter hardiness was assessed using the method of P.I. Lapin. and Sidneeva S.V., on a 7-point scale, and the assessment of decorativeness was done according to the method of Bylov V.N. on a 5-point scale. Under various overwintering conditions during the years of research, semi-climbing roses had good winter hardiness. The studied cultivars did not have any plant damage, despite the fact that winter shelter was not used when growing them, and only annual shoots (2021-2022-2023) and biennial shoots under unfavorable overwintering conditions (2020-2021) were frostbitten. Abundant and repeated flowering is typical for most cultivars of semi-climbing roses. They are resistant to fading and rain. In terms of flowering duration, the continuously flowering cultivar Prairie Joy and Sommerwind had the highest scores. The cultivars Golden Celebration and Harlow Carr scored high when assessing decorative merits - 4.8 points, and Graham Thomas - 4.7 points.