Biomass sorghum ( (L.) Moench) is widely recognized for its high biomass yield potential, high efficiency in converting solar energy into biomass, and high efficiency in water use for biofuel production. Therefore, it could be a sustainable alternative to traditional food/feed crops in south Texas. The objectives of this investigation were to: (1) quantify the growth response and dry biomass productivity of a forage sorghum hybrid (Pioneer 877F) and two high-biomass sorghum hybrids (Blade ES 5140 and Blade ES 5200) in south Texas, (2) determine the radiation use efficiency (RUE) and water use efficiency (WUE) of the sorghum hybrids over two years, and (3) identify variations in WUE and water used among the hybrids. The experiments were conducted at the Texas A&M AgriLife Research Center at Weslaco, Texas, during the 2015 and 2016 growing seasons. There were significant differences among hybrids during the two years in dry biomass, RUE, and WUE. The highest productivities and efficiencies were observed in the biomass hybrids. Blade ES 5200 produced an average dry biomass of 32.8 Mg ha-1 with a leaf area index (LAI) of 6.0 m2 m-2, RUE of 4.92 g MJ-1, and WUE of 6.98 kg m-3. In contrast to the biomass hybrids, the forage hybrid produced the lowest yields. The average dry biomass observed was 20.9 Mg ha-1 with an LAI of 2.6 m2 m-2, RUE of 3.52 g MJ-1, and WUE of 4.28 kg m-3. Our results show that biomass sorghum hybrids can produce up to 66% more biomass than forage hybrids, and they have potential for producing as much as 33 Mg ha-1 with 530 mm of water using drip irrigation in south Texas. Keywords: Biomass sorghum, Crop growth rate, Radiation use efficiency, Water use efficiency.