Abstract: Background and Objectives: Potato production in Indonesia, at a medium altitude, can have a number of problems. Therefore, to increase potato productivity, there must be some alternative. One method is with the application of paclobutrazol. The objective of this study is to investigate the effects of application time and paclobutrazol concentration on the yield of potato seeds (G2 of cultivar medians) grown at a medium altitude. Materials and Methods: This experiment was conducted in the Research Station of Agriculture Faculty of Universitas Padjadjaran at an altitude of 685 m a.s.l. with a D3 rainfall rate and inceptisol soil. The experiment used a randomized plot design: The main plot factor was the application time of paclobutrazol at 30 DAP (days after planting) and 45 DAP, with the second factor being the concentration of paclobutrazol at 0, 50, 100 and 150 ppm. All parameters were tested by analysis of Variance (ANOVA), followed by Duncan's multiple range test at the 5% significance level. Results: Results showed there was no interaction between application time and paclobutrazol application on either the growth or yield of G2 potato seeds. However, application of paclobutrazolat45 DAP showed taller plants, with more and heavier tubers compared to application at 30 DAP. Paclobutrazol application reduced the plants’ height, leaf area and dry weight of the plants. On the other hand, it increased chlorophyll content index, numbers of tubers and weight per plant. The use of50 ppm paclobutrazol resulted in the highest number of potato seeds of cultivar medians at 92.3%. Conclusion: In summary, the application of paclobutrazol at 50 ppm and 45 DAP is an optimal application for increased plant productivity of potatoes at medium altitude.