Switchgrass (Panicum virgatum L.) is considered a good biofuels feedstock candidate. However, limited information is available on its productivity and harvest management in the upper southeastern USA. Our objective was to examine production potential of upland and lowland switchgrass cultivars in response to one- or two-cut management across the region. Upland ('Cave-in-Rock' and 'Shelter') and lowland ('Alamo' and 'Kanlow') cultivars were harvested for 3 yr under one- or two-cut management at eight sites in five states (North Carolina, Kentucky, Tennessee, Virginia, and West Virginia). Across all sites, years, and cutting managements, upland cultivars yielded 12.6 vs. 15.8 Mg ha(-1) for lowland cultivars. Both cultivars yielded more on average with two harvests rather than one, but the effect was greater for upland cultivars (36% more biomass), while lowland cultivars yielded only 8% more biomass with two harvests. Tiller densities were higher for Alamo (lowland) than for Cave-in-Rock (upland) and higher with two-cut than with one-cut management. Early season production of Alamo (a cultivar of southern origin) appeared sensitive to low temperatures. Weak linear responses to precipitation were observed for first-cut biomass, but none was observed for summer precipitation. Lowland switchgrass cultivars appear better suited to biomass production in the upper southeastern USA, due to their greater productivity. Two vs. one cutting per year may be of less advantage for biomass yield with lowland cultivars in this region. However, if upland cultivars are used, two harvests may be of benefit dependent upon production costs and feedstock quality. (c) 2005 Elsevier Ltd. All rights reserved.