Abstract: Background and Objectives: Different compositions of growing media caused different water content, different water retention capacity as well as different watering requirement. Accordingly, accurate watering interval on the growing media of different compositions are expected to increase potatoes’ growth and the second generation of potato seed production at medium altitude. This research was conducted to obtain the composition of growing media and the right watering interval for growth and yield of potato G2 Medians cultivar grown at medium altitude. Materials and Methods: The experiment was carried out at the research station located in Jatinangor, Indonesia. The experiment was using factorial randomized block design, consisted of three levels of growing media compositions, namely soil+compost+husk charcoal (2:1:1), soil+compost+cocopeat (2:1:1) and soil+compost+cocopeat+husk charcoals (2:1:1:1). They were treated by three levels of watering intervals (once in 2, 3 and 4 days). The potato seed planted is first generation (G1) tuber of potato medians cultivar. Results: Results indicated some interactions between growing media compositions and watering interval, affected the rate of stolon percentage and the tubers weight per plant. The compositions of soil+compost+cocopeat (2:1:1) and soil+compost+husk charcoal+cocopeat (2:1:1:1) treated by the watering interval once in 2 days increased the percentage of tuberization (93.33 and 90.86%) and the weight of tubers per plant (335.0 and 355.5 g). As composition of soil+compost+husk charcoal+cocopeat (2:1:1:1) increased the height of plants (58.96 cm), leaf area (5656.44 cm2), dry weight (50.06 g), Shoot-Root Ratio (7.31) and tubers quantity per plant (13.81 knol). The treatment of once in-two-day watering interval expanded leaf area (4752.72 cm2) and plants’ dry weight (48.17 g). The percentage of seed piece tubers was ranged from 88-94%. Conclusion: It was concluded that in Medians cultivar, the use of growing media compositions of soil+compost+cocopeat (2:1:1) and soil+compost+husk charcoal+cocopeat (2:1:1:1) treated by the watering interval once in 2 days increased the percentage of tuberization and the weight of tubers per plant.