Two lines of black bean (Phaseolus vulgaris L.), ‘70001’ and ‘Strain 39’, were grown at between-row spacings of 76, 61, and 46 cm. Cultivation treatments included an uncultivated check and a single cultivation at 1 of 3 plant growth stages: first trifoliolate leaf fully expanded; anthesis; or pod elongation. Root weight, shoot weight, and shoot:root ratio of individual plants decreased linearly as between-row spacing decreased. Biological yield increased linearly as between-row spacing decreased, but seed yield and harvest index did not show significant responses to spacing. None of the measured parameters gave a significant response when the uncultivated control was compared with the average of the 3 time-of-cultivation treatments. Root weight of individual plants and biological yield gave quadratic responses within the 3 time-of-cultivation treatments, both decreasing most markedly with cultivation at the pod elongation stage. Plants of ‘70001’ were larger and lodged less compared to those of ‘Strain 39’. Seed yields of both lines were similar. Results suggest that a single shallow cultivation may be used for black beans grown in narrow rows through anthesis. Although cultivation at the pod elongation stage was generally not detrimental to seed yield, it is not recommended.