Red cabbage (Brassica oleracea var. capitata) is a nutrient-rich crop whose productivity is often limited by poor soil conditions and excessive chemical fertilizer use. This study investigated the effects of foliar-applied phytohormones (salicylic acid [SA], methyl jasmonate [MeJA]) and biostimulants (humic acid [HA], fulvic acid [FA]) on red cabbage growth, yield, and nutritional quality under two substrate conditions (sand [M1] and sand-vermicompost [M2, 80:20 v/v]). A two-season (2022/2023-2023/2024) greenhouse experiment employed a split-plot design with three replications. Results showed that M2 substrate combined with MeJA (3 mg/L) significantly increased plant height (45.5 cm vs. 33.8 cm in control), head weight (1257 g vs. 505 g), and yield (3.18 kg/plant vs. 1.75 kg). MeJA also enhanced nutritional quality, elevating ascorbic acid (58.9 mg/100g), anthocyanin (366 mg/100g), and protein (19.5%) while reducing nitrates (488 ppm vs. 788 ppm). These findings demonstrate that integrating vermicompost with MeJA optimizes red cabbage production sustainably, reducing reliance on synthetic inputs.