Annals of Warsaw University of Life Sciences – SGGW Horticulture and Landscape Architecture No 31, 2010: 35–41 (Ann. Warsaw Univ. of Life Sc. – SGGW, Horticult. and Landsc. Architect. 31, 2010) Branching stimulation in Hosta sp. MARIA WITOMSKA, ADAM JASZCZUK, AGNIESZKA ILCZUK Department of Ornamental Plants, Warsaw University of Life Sciences – SGGW Abstract: Branching stimulation in Hosta sp. In 2007–2008 trials were undertaken to stimulate branching in hosta, a popular garden perennial. Two cultivars were used in the experiment: ’Wide Brim’ and ‘Patriot’. The young single stem plants were either decapitated or sprayed twice or three times with Arbolin 038 (containing GA 3 and BA) at monthly intervals. Removal of the apical bud did not stimulate branching in the first season and decreased the offshoot production in the second year in both hosta cultivars. During the first year two sprayings with Arbolin 038 stimulated bran- ching only in ‘Wide Brim’ while three sprayings were effective for both cultivars. Observations made in the second growing season indicate that two treatments with Arbolin 038 were sufficient to provoke branching in both hosta cultivars re- sulting in marketable plants. Key words: apical dominance, gibberellic acid, benzyladenine, Arbolin 038, production cycle. INTRODUCTION Hostas are long-lived ornamental peren- nials tolerant to a wide range of envi- ronmental conditions and appreciated because of their decorative leaves. There are numerous hosta cultivars varying in vigour as well as in leaf and flower colours. They are planted on borders and in containers or used as ground covers (Johns and Johns, 1990; Rhodus, 1995) while their detached leaves are gaining popularity as the florists’ greens used in flower arrangements (Rabiza-Świder and Skutnik, 2008). A traditional propagation method by plant division is not com- mercially efficient. In the seventies of 20th century trials to increase efficiency of hosta propagation were undertaken in the USA where the species soon began to dominate among those propagated in vitro (Mayer, 1980). Micropropagation, though a very efficient technique, pro- longs the hosta production cycle up to three years (Gabryszewska and Wojtania, 2005). Commercial hosta plants should have at least 2–3 shoots in a rosette. Most cultivars do not branch profusely because of the strong apical dominance (Schmid, 1991) therefore special treatments are needed to intensify and to shorten pro- duction cycle. Application of gibberellic acid and benzyladenine to hasten plant growth and shorten production cycle has widely been recommended for many ornamental plants, especially trees and shrubs (Grzesik and Rudnicki, 1989). Cytokinins stimulate growth of axillary buds in plants while gibberellins enhance their elongation (Kozłowska, 2007). A profuse branching after a cytokinin application was observed in different ornamental perennials (Dunwell, 1999; Martin and Singletary, 1999). Also our