Among the wide range of ornamental plants, the representatives of the genus Allium L. are of great interest, as they possess numerous useful properties – medicinal, food, melliferous, vitamin and ornamental. The purpose of our research was to study of adaptive and bioecological features of ornamental Allium L. species and to determine the direction of their use in landscape design. The research subjects were 10 species of Allium L. from the collection of ornamental plants. The research was carried out on the experimental site of the Laboratory of Ornamental Plants, using the methods: Cheremushkina (2004), Pavlova (2010), Methodology of phenological observations in botanical gardens (1979). Based on the results of phenological observations, a spectrum of the studied species of ornamental alliums was compiled. According to our observations, Allium caeruleum Pall and Allium atropurpureum Waldst. et Kit begin to grow in the middle of February. Allium moly L. sprouts later than all others; it grows and develops until the flowering stage in only 3 weeks, blooms for 2 weeks and seeds ripen 10-15 days after the end of flowering, and the full cycle from germination to seed ripening occurs in an average of 74.5 days. Then there is a period of dormancy until the vegetative phase begins next year. Allium atropupureum Waldst. et Kit emerges in the second half of February - early March, it takes 59 days to produce buds, flowering lasts 12 days and the seeds ripen 20 days after the end of flowering, then the plant begins a long period of dormancy. The full cycle of growth and development from germination to full ripening of seeds lasts 120 days. All species of alliums grown by us under the conditions of the „Al. Ciubotaru” National Botanical Garden (Institute) go through a full development cycle, bloom and reproduce, which characterizes the stability of their cultivation. Such species as – Allium giganteum Regel, Allium aflatunense B.Tedtsch, Allium chistophii Trautv., Allium moly L., Allium sphaerocephalon L., Allium atropurpureum Waldst. Et Kit, Allium caeruleum Pall, Allium spledens L., Allium schoenoprasum L., Allium odorum L. are recommended for growth in ornamental flower beds, for group plantings on lawns, rock gardens and for cut flowers.