Abstract The paper reports the results of a research program aiming to evaluate the agronomic, and energy sustainability of the biomass production by perennial non-food herbaceous crops irrigated with different kinds of marginal waters. In four different sites (Bologna, Padova, Reggio Calabria, and Catania) the same four species ( Arundo , Typha , Phragmites , and Lythrum ), usually tested without irrigation, were planted and monitored during 2008–2010. The results show that a planting density of 10 m −2 is necessary to obtain a maximum dry yield levels already from the second year of transplanting. The maximum productivity was obtained with Arundo (close to 100 Mg ha −1 y −1 in Bologna and 86 Mg ha −1 y −1 in Padova, 50–60 Mg ha −1 y −1 in the southern locations). Lythrum productivity ranged from 5.2 to 9.2 Mg ha −1 y −1 in all the RUs, with the exception of Reggio Calabria. Typha (around 10 Mg ha −1 y −1 at the third year) and Phragmites (5–8 Mg ha −1 y −1 ) gave significant production only in the northern locations. The HHVs were close to 15.5 MJ kg −1 for Phragmites (except for Catania and Reggio Calabria with 20.0 MJ kg −1 ) 18.0 MJ kg −1 for the Arundo (except for Catania with 20.0 MJ kg −1 ), 18.5 MJ kg −1 for the Typha and Lythrum (except for Catania with 20.0 MJ kg −1 ).