Biological characteristics of cultivars of Hibiscus syriacus L. grown in Donetsk Botanical Garden

The morphobiological and phenological features of ten cultivars of Hibiscus syriacus L. were investigated. These cultivars were introduced from Simferopol Botanical Garden and are growing in the collection of Donetsk Botanical Garden. The plants grow in the open ground and are protected from the cold. The cultivar Carneus Plenus exhibited the highest degree of shoot freezing, up to 50% of the length. Vegetation starts almost simultaneously in all cultivars – from the second decade of April. Blue Bird, Coeruleus Plenus, Pink Giant, and Roseus Plenus bloom earlier than other cultivars, from late June to early July. Blue Bird, Coeruleus Plenus, Pink Giant, and Hamabo have abundant and prolonged flowering, lasting up to two months or more. The high rooting percentage of lignified cuttings prepared in an early spring greenhouse with a fog cannon before the bud swelling phase demonstrated the effectiveness of this propagation method for H. syriacus. Plants obtained from rooted cuttings should be planted in their permanent growing location at the beginning of the next growing season. During the first two years after planting the rooted cuttings in the introduction nursery, freezing of the shoots at the level of the root collar was observed. However, with the onset of vegetation, the plants experience massive shoot regrowth and restoration of the crown shape inherent to the cultivar, as well as flowering. The following cultivars were selected for their abundant and prolonged flowering: Blue Bird, Coeruleus Plenus, Hamabo, Monstrosus, Pink Giant, Rubis, and Woodbridge. They are of interest for landscape design.