The physical, physiological and biochemical changes in developing seeds of cauliflower (Brassica oleracea L. var, botrytis) cultivar Kibo Giant were followed from 7 days after anthesis up to maturity, grown under field conditions. Silique growth and weight, seed weight, germination capacity and speed, seedling length and dry weight, dehydrogenase activity, protein and oil accumulation followed almost a sigmoidal pattern. Seeds started precocious germination from 28 days after anthesis onwards. Cell membrane integrity increased with the advancement of seed maturity. Dehydrogenase activity correlated positively with seed quality and seedling vigour, and negatively with seed moisture content. A significant amount of oil accumulation started later than protein, but continued even after protein accumulation ceased. While protein accumulation slowed down earlier, oil accumulation continued up to harvest. The best time to harvest the seed crop was within a week after physiological maturity (49 days after anthesis), which identified visually by change in colour of siliques and seeds from green to pinkish yellow and brown, respectively.