We investigated the effects of planting density and fertilizer type (ferrous ferric chloride (FFC) vs. fermented compost) on the growth and yield of yacon tubers. Yacon was cultivated in an experimental field consisting of 18 4 m × 5 m blocks with each block randomly assigned to one of six treatments (combinations of planting densities and fertilizers) with three replications. No insect or specific disease damage was observed over the course of the experiment. Yacon tubers were well developed and were harvested at maturity. Planting density affected tuber number, total yield, and tuber weight. Yacon planted at the highest density (treatment 2) showed the lowest tuber yield. Proper density for cultivating yacon was 100-cm ridge widths and 80-cm intra-row spacing in this experiment. Maximum yield (total tuber weight per plant) of yacon tubers was obtained with 34.0 kg/10a of FFC. Although FFC at 68.0 kg/10a did not increase yield (total tuber weight per plant), it did increase tuber weight.