Leafy greens such as kale, arugula, spinach, and lettuce are among the most commonly grown crops in hydroponic and vertical farm operations. However, maintaining optimal growing conditions can be challenging, as small changes in environmental factors may affect plant growth, nutrient uptake, and the development of physiological disorders.
One study examined how dissolved oxygen levels in hydroponic nutrient solutions affect the growth of kale and arugula. Researchers found that maintaining adequate oxygen concentrations in the root zone can significantly enhance plant development. Higher dissolved oxygen levels supported stronger root systems and improved shoot growth, suggesting that oxygen management can be a critical tool for maximizing productivity in hydroponic leafy green production.
Another study investigated how light intensity and production systems influence nutrient solution refill strategies for hydroponic spinach. As plants grow, they continuously remove water and nutrients from the solution, requiring growers to periodically replenish reservoirs. The research showed that optimal refill strategies vary depending on lighting conditions and the type of production system used. Adjusting refill practices based on plant growth rates and environmental conditions helped maintain stable nutrient concentrations, improving plant performance and resource efficiency.
A third study focused on preventing lettuce tipburn, a common physiological disorder in vertical farming systems. Tipburn occurs when rapidly growing lettuce leaves experience localized calcium deficiencies, often due to limited air movement within dense plant canopies. The research evaluated how optimizing downward airflow in vertical farms can improve air circulation around developing leaves. Results showed that targeted airflow management reduced the incidence of tipburn while maintaining healthy plant growth.
Together, the studies highlight the importance of precisely managing environmental and system variables in controlled environment agriculture. Factors such as root-zone oxygen availability, nutrient solution management, lighting levels, and air circulation all interact to influence crop performance.
By refining these aspects of production, growers can reduce crop losses, improve plant quality, and make more efficient use of resources. The findings provide practical guidance for commercial hydroponic and vertical farm operators working to scale production while maintaining consistent crop quality. As controlled environment agriculture continues to expand, research-driven strategies like these will play an increasingly important role in supporting reliable, high-quality production of fresh leafy greens year-round.
Dr Ferrarezi stated that this research was conducted, "because there is limited information about oxygenation levels, nutrient replacement strategies, and adequate downward airflow. Some of these concepts are known to growers from their cultivation experience, but providing research-based recommendations can help them reduce costs, increase sustainability, and improve resource-use efficiency. " The Trial was conducted over multiple seasons and with different cultivars to generate a robust dataset that enables growers and researchers to apply these results to larger areas with greater confidence.
Dr. Ferrarezi is a Professor of Controlled Environment Agriculture Crop Physiology and Production at the University of Georgia College of Agriculture and Environmental Science.
The full articles can be found on the ASHS HortScience electronic journal website at: https://doi.org/10.21273/HORTSCI18774-25, https://doi.org/10.21273/HORTSCI18828-25 and https://doi.org/10.21273/HORTSCI18934-25
Established in 1903, the American Society for Horticultural Science is recognized around the world as one of the most respected and influential professional societies for horticultural scientists. ASHS is committed to promoting and encouraging national and international interest in scientific research and education in all branches of horticulture.
Comprised of thousands of members worldwide, ASHS represents a broad cross-section of the horticultural community - scientists, educators, students, landscape and turf managers, government, extension agents and industry professionals. ASHS members focus on practices and problems in horticulture: breeding, propagation, production and management, harvesting, handling and storage, processing, marketing and use of horticultural plants and products. To learn more, visit ashs.org.
