Perennial grasses are valuable biomass feedstocks due to their potentially high biomass yield and environmental benefits. This study aimed to compare 7 cool season: tall wheatgrass, bulbous canary grass, reed canary grass, tall fescue, perennial ryegrass, orchard grass, and smooth brome grass and 3 warm season perennial grasses: mis-canthus, switchgrass, and giant reed for biomass yield, quality, and energy balance at 2 harvesting periods (autumn and winter to early spring) over 3 growing seasons in cold (Cankiri, Turkey) and warm (Adana, Turkey) semiarid environments. Harvests in winter and spring both led to considerable yield losses with all of the grass species in both locations, while it promoted biomass quality by reducing the moisture and ash contents of the warm season grasses in both locations, and the cool season grasses only in Cankiri. In contrast, autumn harvest provided significantly lower moisture and ash contents in the cool season grasses grown in Adana over the 3 years, where it was observed that, on average, giant reed exhibited the highest biomass productivity in both locations. Furthermore, bulbous canary grass and tall wheatgrass were found to be the most productive species in the study among the cool season grasses. Additionally, bulbous canary grass in Adana and tall wheatgrass in Cankiri achieved considerably higher energy ratios than the warm season grasses, mainly as a result of a lack of energy input for irrigation. In this sense, these 2 cool season grasses may be considered as alternative bioenergy crops in semiarid environments for sustainable biomass production.