Global demand for high-quality onion bulbs is rising, and there is a need for innovative, resource-efficient cultivation systems that stabilize production while mitigating soil-related limitations. Hydroponic cultivation systems, widely adopted for high-value crops, offer a promising alternative by enabling precise environmental control, optimized nutrient management, and reduced exposure to soil-borne diseases and weed competition. However, hydroponic methods for onion bulb production remain underexplored despite their success in other vegetable crops. Knowledge gaps exist in root-zone aeration dynamics, nutrient uptake efficiency, and the economic scalability of hydroponic systems for onion production. The objective was to determine the growth performance, bulb quality, yield, and financial feasibility of growing onion varieties across these systems. This study evaluated the comparative performance of three onion varieties: Candy Onion (intermediate-day), Walla Walla Onion (long-day), and Yellow Sweet Spanish Onion (long-day), grown under three hydroponic systems (Deep Water Culture (DWC), Kratky, and Drip Irrigation) along with inground production. The study followed a randomized complete block design with three replications. Key growth parameters, such as plant height, leaf number, and chlorophyll content, were recorded each week. Yield attributes, including bulb diameter, weight, total fresh and dry biomass, and harvest index, were analyzed after harvest. Moreover, bulb quality parameters such as total soluble solids (TSS), sulfur content, and pungency (pyruvic acid concentration) were assessed for consumer acceptability. The economic evaluation considered were the cost of cultivation, gross and net returns, and the benefit-cost ratio to determine the financial viability of hydroponic onion production for small-scale farmers in Kentucky. Despite the higher initial setup cost, hydroponic systems are projected to provide about 25% greater financial returns by reducing labor, pesticide, and fertilizer expenses, making them a sustainable solution for onion production. This study provided insight for farmers, researchers, and policymakers on integrating hydroponic technology for enhanced onion production, economic profitability, and sustainable agricultural practices. Further studies are necessary to validate the findings and guide best-practice recommendations for optimizing onion cultivation and supporting year-round production in Kentucky and beyond.
