<p>Traditionally, fermented panchagavya is prepared by mixing five cow products namely dung, urine, milk, curd, and ghee for use in agriculture. The most used and reported ratio of dung: urine: milk: curd: ghee is 10.0: 6.0: 4.0: 4.0: 1.0 for panchagavya. To increase the plant growth-promoting activity of panchagavya preparation, central composite design (CCD) was used to optimize four cow products (dung, urine, milk, and curd) keeping ghee constant and quality was measured in terms of gibberellic acid (GA) produced as a response during the fermentation. A total of 30 experimental runs were prepared with different ratios of cow products and incubated at room temperature for 20&#xa0;days. The quadratic model was found significant and suggested the optimized panchagavya having dung: urine: milk: curd: ghee ratio of 18.0: 7.0: 2.5: 9.0: 1.0. An experimental run for the suggested ratio gave 338.0&#xa0;µg&#xa0;mL⁻¹ GA which was 1.36 times more GA than the commonly used ratio of five cow products. A 50.0 L fermented panchagavya with optimized ratio was prepared and was tested on groundnut (<i>Arachis hypogaea)</i> in the field. The fermented panchagavya has shown the positive effect on plant growth and increased the plant height, shoot length, root length, and nodule numbers by 1.46 1.41, 3.29, and 3.00 times, respectively than the control. The leaves numbers, width, and length were also increased 1.90, 1.12, and 3.13 times, respectively in the panchagavya treated plants. Field evaluation showed an about fivefold increase in the yield compared to control.</p>