Rhubarb (Rheum rhabarbarum L.) is a popular springtime vegetable known for its vibrant red stalks and tart flavor. This study explores the intriguing biochemical profile of rhubarb and highlights its potential health benefits. Hydroponic systems (volcanic slag and volcanic slag with gravel significantly increased rhubarb yield (both fresh and dry weight) by 2.6-6.0 times compared to traditional soil, especially in June and July. Rhubarb grown hydroponically also produced 1.6-1.8 times more petioles per plant, each with 1.6 times the fresh weight and 1.1 times the dry weight of soil-grown petioles. Compared to soil, hydroponics significantly increased the levels of extractive substances (1.2-3.2 times), flavonoids (1.4-3.7 times), and phenols (1.2-4.0 times). The research evaluated antioxidant activity, with hydroponically grown rhubarb demonstrating superior performance, particularly in the volcanic slag + gravel plants, which exhibited the strongest antioxidant activity. In contrast, the soil-grown plants displayed the lowest antioxidant activity. According to the FRAP analysis, 1 gram of plant dry mass recovered more iron in the soil-grown variant, followed by the volcanic slag variant. These findings suggest that hydroponic systems, especially those using the volcanic slag substrate, hold promise for cultivating rhubarb enriched with health-promoting compounds in the Ararat Valley.