Condensed tannins (CT) from sericea lespedeza [Lespedeza cuneata (Dumont de Courset) G. Don], a hardy and widely adapted forage legume, have potential for methane emission suppression, rumen protein bypass, gastrointestinal nematode suppression, and pest fly suppression in ruminants. Nitrogen (N) from this herbaceous legume can also be an important component of crude protein in ruminant diets. The concentrations and yields of CT and N, however, have not been studied across a wide range of environments, harvest regimens, or plant maturities. Our results from Texas and Georgia indicate that CT concentrations increased with rainfall, decreased with maturity, and were highly dependent on harvest regimen (P ≤ 0.05). Condensed tannin concentrations ranged (P ≤ 0.05) from 32.7 to 106.1 g CT kg−1 dry matter (DM) and CT DM yields from 274 to 771 kg ha−1 yr−1. Nitrogen concentrations ranged (P ≤ 0.05) from 14.6 to 28.4 g kg−1 DM and N DM yields from 46 to 231 kg ha−1 yr−1. If pellets or hay of sericea lespedeza are to be commercialized specifically for their CT and N content, analysis and labeling will be beneficial because of this variability.