Germination percentage was increased and emergence was accelerated when two or more subterranean clover (Trifolium subterraneum L.) seeds were planted in close physical proximity instead of singly. The effect was enhanced when a nutrient solution was supplied. However, raising the ambient temperature from 10 to 15C and from 15 to 20C either reduced the effects of seed aggregation and nutrient availability or caused the effects to be evidenced during a shorter time interval. As the influence of close seed spacing and improved nutrient availability were more pronounced at cool temperatures, they therefore could be of importance to stand establishment from new seedings in the California annual range when rainfall adequate to permit germination occurs later than normal.