An experiment was conducted with four sowing dates commencing from the onset of rains during the 1976/77 Maha season, to determine the optimum time of sowing the local cowpea variety, MI-35, under coconut at Kirimetiyana Estate, Kirimetiyana. The study indicated that plants attained the maximum vagetative and reproductive growth when seeds were sown with the onset of rains, as indicated by a reduction in plant height, weight of shoots, number of pods and number of seeds per pod with delayed sowing. Plants established with the onset of rains also gave the highest yield of seed and the low seed yield due to later sowing resulted mainly from a reduction in the number of pods per plant rather that a substantial seed yield could be obtained when seeds are sown within a period of three weeks from the onset of rains