Understanding the growth dynamics of grass–legume swards is critical as pastoral management practices are adapted to varying economic constraints and emerging environmental considerations. Efficient management must synchronize the use of accumulated herbage with the needs of grazing livestock. This must be accomplished against the dynamic background of within and among year weather patterns interacting with herbage growth and grazing animal behavior. In the Appalachian region of the eastern United States, pastures often are dominated by orchardgrass (Dactylis glomerata L.) and white clover (Trifolium repens L.). We determined botanical composition and herbage productivity of orchardgrass and white clover swards during four consecutive years when managed as a function of canopy development and regrowth interval. Productivity was influenced by defoliation practices when mixtures were managed according to canopy development. Productivity was greatest when swards were managed as hay or when clipped to a 5-cm residue each time mean canopy height reached 20 cm. White clover declined and orchardgrass increased in the sward irrespective of defoliation treatment. Botanical composition of mixtures with the erect growing orchardgrass tended to be more stable, whereas swards including the decumbent orchardgrass tended to be invaded by weeds. Some increase in productivity occurred during the first growing season when mixtures were clipped at either 2- or 4-week intervals. Regardless of defoliation practice, white clover, and in some instances orchardgrass, presence declined during two consecutive growing seasons with various other volunteer grasses and forbs contributing to productivity. Productivity and persistence of sown sward components may be less dependent on management practices than on the expression of interactions responding to within and among year weather patterns.