Temu ireng (Curcuma aeruginosa Roxb.) is a traditional medicinal plant that has long been used to treat various diseases, such as fever and pain. Temu ireng contains various bioactive compounds, such as essential oils, saponins, flavonoids, and curcuminoids. Seeing the various prospects of the temu ireng rhizome, an increase is sought by expanding the production area and improving the quality of cultivation by intensively fertilizing using corn cob biochar and cassava peel compost fertilizer. The research was conducted from November 2022 - April 2023 at the UNS Faculty of Agriculture Laboratory in Jumantono. The research was arranged in a completely randomized design (CRD) with two treatment factors and repeated 3 times. The factors used were the application of corn cob biochar (0, 160, 240, and 320 g/polybag) and cassava peel compost fertilizer (0, 100, 200, and 300 g/polybag). The observation variables consisted of plant height, rhizome fresh weight, rhizome dry weight, and temu ireng flavonoids. Data analysis in this study was quantitative. The parameters were analyzed by variance (ANOVA) test at the 5% level, if there was a significant difference, then the DMRT test at the 5% level. The results showed that at 24 MST the combination of corn cob biochar and cassava peel compost fertilizer produced a real difference. The use of 320 g/polybag corn cob biochar and 300 g/polybag cassava peel compost fertilizer increased plant height to 139.3 cm, fresh weight to 656.21 g, and dry weight to 348.17 g, and the flavonoid content was 0.057%.