Purpose <p>This study aimed to determine the optimal fertilization strategy for maximizing <i>Tagetes minuta</i> L. (aromatic marigold) yield and essential oil production in the Western Himalayan region, focusing on phosphorus (P) and potassium (K) fertilization levels.</p> Methods <p>A field experiment was conducted over two years (2021 and 2022) with five levels of phosphorus (P0:0, P1:40, P2:80, P3:120, P4:160&#xa0;kg ha^− 1) and three levels of potassium (K0:0, K1:30, K2:60&#xa0;kg ha^− 1). The effects of these treatments on total biomass yield, essential oil yield, oil quality, and nutrient content were evaluated. Data were analyzed for interaction effects between P and K treatments.</p> Results <p>The highest total biomass yield was observed at P3 (120&#xa0;kg ha^− 1) and P4 (160&#xa0;kg ha^− 1) for phosphorus, combined with K1 (30&#xa0;kg ha^− 1) for potassium during both the years. The highest essential oil yields were recorded at P3K1 and P4K1, with 129.6% and 242.4% increase over the control during 2021 and 2022, respectively. A strong positive linear relationship was found between essential oil yield and both P (<i>r</i> = 0.99, <i>p</i> = 0.01) and K (<i>r</i> = 1, <i>p</i> = 0.01). The Z-β-ocimene content was highest at P3 with 1.28% and 15.12% increase over control during 2021 and 2022, respectively.</p> Conclusions <p>An optimal fertilization ratio of 120&#xa0;kg P ha^− 1 and 30&#xa0;kg K ha^− 1 is recommended for maximizing <i>T. minuta</i> yield and essential oil production. Balanced fertilization enhances productivity and oil quality while avoiding negative effects of excessive fertilization, providing insights for sustainable marigold cultivation.</p> Graphical Abstract <p></p>