The Mediterranean climate is characterized by low summer rainfall, high temperature and evapotranspiration, which combine to limit plant CO2 assimilation reducing biomass yield of spring-summer crops. Climate change scenarios predict even lower rainfall and prolonged summers increasing aridity. Therefore, it is important to identify crops that can use available water efficiently and can withstand prolonged periods of waterdeficit. The present experiment assessed the biomass yield and quality of two ecotypes of Arundo donax L, one ecotype of Saccharum spontaneum spp. aegyptiacum and three hybrids of Miscanthus, namely the commercial M. × giganteus, and two new clonal hybrids, GNT9 and GNT10, during the first year of establishment with sufficient irrigation to prevent water deficits. The Miscanthus clonal based hybrids GNT9 and GNT10 have been selected for the adaptability to drought conditions among the F1 generation obtained from interspecific Miscanthus cross. Measurements of total aboveground biomass, stem density, stem weight and biomass quality were recorded from one harvest following the first year after establishment to assess the different establishment phase performances between genotypes. S. spontaneum produced the highest dry biomass yield during the first year of the trial due to the combination of high stem density and stem dry weight. A. donax ecotypes had the highest stem weight, but yields were reduced by the low stem density. In contrast, the yield of Miscanthus hybrids was constrained by low stem weight. Miscanthus hybrids had higher cellulose and hemicellulose and lower content of lignin and neutral detergent soluble (NDS) than A. donax and S. spontaneum whose composition was found to be similar.