Seed development and maturation comprise a series of events involving cell division/ histo-differentiation, retains deposition, and desiccation. Development of green gram seed has been divided into eight consecutive stages; 5, 10, 15, 20, 25, 30, 35, and 40 days after anthesis (DAA). During seed development, chlorophyll content declined, while carbohydrate and protein contents were increased, suggesting their supportive role in germination and early seedling growth. Only the latter two stages of development (35 and 40 DAA) were taken into consideration for germination potential and seedling metrics, such as vigor index, because seeds produced up to 30 days after anthesis did not germinate at all. The highest germination potential was found in seeds produced at stage 40 DAA in the first and second years, respectively, at 81.24 % and 80.99 %. The peak vigor was noted at 40 DAA, when the average of all genotypes and treatments was calculated. When harvested at 40 DAA, the "Samrat" variety seeds that were grown following seed treatment with Silver nanoparticles (Ag-NPs) had the highest vigor status. Therefore, the best time to harvest green grams for seed is 40 DAA since that is when seed vigor reaches its peak.