In the Nikitsky Botanical Gardens there have been collected 2456 species, cultivars and forms of 8 flowering ornamental crops: garden roses, lilacs, tulips, irises, chrysanthemums, clematis, cannes. As a result of long-term complex varietal studies, the main valuable features of cultivars under the conditions of the south of Russia have been revealed, as well as the cultivar sources of these traits for breeding. Six features are common to all studied cultures: abundant flowering, long-term flowering, pure and original color of the flower, resistance to fading color under sunlight, low incidence of disease, high ability to vegetative reproduction. Also the specific features valuable for each culture have been identified: early-flowering of chrysanthemums and lilacs, late flowering of tulips and irises, shape constancy of the flower and presence of more than one flower per stem of tulips, large size of the flowers and inflorescences of lilacs, original form of the flower of lilies, tulips and clematis, original color of cannes leaves, frost-resistance of chrysanthemum and drought-resistance and dropping the faded flowers of cannes. For garden roses the most valuable trait is the strong aroma of flowers, because its presence allows to use rose cultivars for aromatherapy rosaries in recreational areas. As a result of the study in the floral ornamental collections of the Nikitsky Botanical Gardens, about 500 cultivars were identified as potential sources of valuable features for selection under the conditions of the south of Russia.