Container-grown geranium may experience delayed flowering with leaf chlorosis due to limited nutrient supply in growing medium and high carbon-to-nitrogen ratio. It may be beneficial for both growth and ornamental performance to optimize substrate composition and apply biostimulants. In the present work, we assess how the effect of eco-enzyme level and organic growing media preparation on geranium growth and flowering was interactive. The factorial randomized block design evaluated three concentrations of eco-enzyme (0, 15 and 30 mL L-1) and three media mixtures composed of cocopeat, manure, and rice husk biochar. The medium was well balanced 1:1:1, and a favorable bulk density, porosity and water-holding capacity were obtained which helped in the enhancement of proper root development as well as nutrient uptake. Application of eco-enzyme at 15–30 mL L-1 increased plant dry weight by 24.5–49.1% and flower cluster number by 31.1–59.0% in comparison to untreated plants. The 1:1:1 medium increased flower number and cluster diameter by 18.9% and 5.3% compared to the 1:1:2 formulation, respectively, and 30 mL L-1 eco-enzyme increased flower number further by 25.8%. All these improvements combined to facilitate earlier, fuller flowering and a vigour of the plant. Consequently, incorporating an eco-enzyme biostimulant application along with the optimized organic substrate is a practical and sustainable approach to increase geranium's production in addition to improving its appearance.