The experiments were carried out on highbush blueberry 'Herbert' both on in vitro cultures and plants in vivo. In the case of the in vitro study, the modified Zimmerman and Broome (1980) medium was used. For the first subculture dikegulac was tested at a 0.1-10 mgl-1 concentration together with 2iP (5mgl-1). For the second subculture, dikegulac (1-4mgl-1) was added both into medium supplemented with 2iP (10 mgl-1), and into medium without 2iP. In the case of the in vivo study, dikegulac (100-1000 mg l-1) was applied as a foliar spray on four-month old plantlets. Dikegulac (0.1-5 mg l-1) gradually slowed down the elongation of axillary shoots in vitro, in the presence of 2iP at a lower (5 mg l-1) concentration. It also retarded development of adventitious shoots, while proliferation of axillary shoots was unaffected. Cultures grew very slowly when 2iP was omitted regardless of the concentration of the retardant Plants sprayed with dikegulac (1000 mg l-1) solution in vivo developed more lateral shoots which were shorter, and the plants had reduced leaf blades. Cuttings collected from plants treated with retardant rooted better, compared with the control. Dikegulac may be useful to keep the germplasm bank and in propagation of highbush blueberry, both in vitro and through cuttings.