Dioscorea seeds germinate best in spring. They are short day plants. The best temperature for germination is 25-30 °C. I germinate Dioscorea elephantipes in 10 cm deep trays filled with a mixture of 50% regular potting soil and 50% pumice (Bims). I cover the seeds with a 0.5 - 1 cm layer of this soil mix. Spray well from above to moisture the soil but do make it soaking wet. maintain high air humidity untill most seeds have germinated. This usually takes 2-4 weeks.