Variety × spacing and variety × sowing date trials in south-east Tanzania showed that the long-season spreading bunch groundnut variety Red Mwitunde (A. hypogaea ssp. hypogaea var. hypogaea) was less tolerant of delayed sowing and more tolerant of wide spacing than Natal Common, a short-season upright bunch variety (ssp. fastigiata var. vulgaris). The same variety × spacing and variety × sowing date interactions were detected in groundnuts intercropped with cassava (Manihot esculenta). These observations help to explain the farmers’ preference for Red Mwitunde despite the higher trial yields of Natal Common.