At the Experimental Farm of University of Life Sciences in Lublin (central-eastern Poland), two single-factor trials were conducted with two dedicated bioenergy crops. Virginia fanpetals (Sida hermaphrodita L. Rusby) perennials, and basket willow (Salix viminalis L). In the first set of experiments, the influence of seed dressing on the height of Virginia fanpetals' yields, from the third to fifth year of research (2005-2007) was examined. Seed dressing of Virginia fanpetals led to significant increase in biomass yield (2 t/ha) and production of energy per hectare (18.5%), in comparison to the control plot (without dressing). In the second set of experiments, the yields of Virginia fanpetals, reproduced by root cutting, and two willow clones were examined, from the fourth to sixth year of research (2006-2008). Willow's plots were planted with dormant, unrooted cuttings. Based on averages from three years of tests, significantly higher yields (5 t/ha) of dry matter and more production of energy per hectare (30.5%), were obtained from Virginia fanpetals' trials, than that of the tested willow. (C) 2011 Elsevier Ltd. All rights reserved.