The insect frass fertilizers are considered eco-friendly fertilizer due to their low heavy metals content and adequate contents of macronutrients, secondary nutrients, and micronutrients. Protaetia brevitarsis larval frass (PBF) can provide nutrients that contribute to increased crop productivity. This paper presents the determination of an optimum application rate of PBF for ginseng sprout growth in commercial potting soil. Ginseng was seeded in four different media including commercial potting soil (control), a mixture of 10% PBF, 30% perlite, and 60% cocopeat (PBF 10%), a mixture of 20% PBF, 30% perlite, and 50% cocopeat (PBF 20%), and a mixture of 30% PBF, 30% perlite, and 40% cocopeat (PBF 30%). The results showed that germination rates for all PBF treatments were significantly higher than the control. Additionally, plant height and leaf length of ginseng sprouts were significantly higher in the PBF 20% and PBF 10% treatments compared to the control and PBF 30% treatments. Electrical conductivity of the potting soil with PBF was significantly correlated with plant height, stem length, and root dry weight (P < 0.001). These findings suggest that applying PBF at a rate of 20% is ideal for promoting ginseng sprout growth in commercial potting soil. This study on PBF shows promising potential for ginseng sprout production and its use in high-value, eco-friendly processes.