In order to improve the growth of sugarcane plantlets, this study examined the effects of a seaweed (Ascophyllum nodosum) extract on shoot and root dry mass accumulation of plantlets budding from segments taken from apical, medial and basal parts of culms of the RB867515 variety. The experiment was a 3 x 2 factorial (three culm sections x kelp extract applied at 2.0 l.ha-1 and control) at the Sugar Cane Research Station at the Federal University of Paraná, Brazil. Results showed improvement in shoot and root dry mass accumulation in plantlets budding from the basal part of culms following treatment with the A. nodosum kelp extract.