Editorial: Vertical Farming: New Trends, Products, and Production Approaches

José Pinela^1,2*Maria Inês Dias²Costanza Ceccanti³Michael Martin^4,5

• ¹Instituto Nacional de Investigação Agrária e Veterinária (INIAV), Vairão, Vila do Conde, Portugal
• ²CIMO, LA SusTEC, Instituto Politécnico de Bragança, Bragança, Portugal
• ³Department of Agriculture, Food and Environment, University of Pisa, Pisa, Italy
• ⁴Life Cycle Management, Sustainable Society, IVL Swedish Environmental Research Institute, Stockholm, Sweden
• ⁵Department of Sustainable Development, Environmental Science and Engineering, KTH Royal Institute of Technology, Stockholm, Sweden

As global urbanization accelerates and conventional agriculture faces mounting pressures from climate change, land degradation, and resource scarcity, vertical farming (VF) and controlled environment agriculture (CEA) have emerged as disruptive solutions (Erekath et al., 2024). This Research Topic brings together twelve innovative articles, including empirical studies, comprehensive reviews, and technological assessments that reflect the breadth and maturity of current research in this field. Organized around four interconnected axes, namely urban integration and environmental performance, light optimization and crop enhancement, production systems and postharvest innovation, and socioeconomic and systemic perspectives (Figure 1), these contributions collectively shed light on critical pathways towards more resilient, efficient, and equitable plant food systems. At the intersection of agriculture, architecture, and sustainability, Blom et al. explored the synergistic integration of VF into various building typologies in the Netherlands. By modeling scenarios in apartments, offices, restaurants, swimming pools, and supermarkets, the study quantified how residual resources such as heat, greywater, and nutrient-rich waste can be leveraged to reduce external inputs required by VF. Apartments demonstrated strong potential for thermal energy recovery and full provision of vegetables using resident-generated waste streams, while restaurants and pools offered viable opportunities for water reuse. Offices and supermarkets showed limited resource synergies due to insufficient greywater and nutrient outputs. The study highlighted the need for context-specific strategies and the potential of integrated systems to reduce environmental footprints in urban areas.Complementing this architectural perspective, Martin et al. presented a life cycle assessment of modular cabinet vertical farms situated near consumption points, such as office cafeterias, in Stockholm. Their analysis confirmed that the proximity to end-users, combined with renewable energy use and shared infrastructure, can result in greenhouse gas (GHG) emissions that are lower or comparable to those of traditional supply chains. The study also emphasized that environmental performance is highly sensitive to local factors such as the electricity mix and methodological choices, underscoring the importance of regional context and careful system design.Broadening the scope, Sowmya et al. provided a conceptual review of VF as a strategy to address food insecurity and environmental degradation in rapidly urbanizing areas. The authors highlighted the ability of VF to enable year-round production of crops, such as fruit and horticultural products, through soilless techniques like hydroponics and aeroponics, particularly in regions with limited arable land and water resources. They outlined VF ecological, nutritional, and socio-economic benefits, while also noting that it remains costly and technologically complex, with adoption of challenges especially pronounced in low-income and developing urban contexts. A key contribution of the paper is its call for increased scientific research, standardization, and collaboration between academia and industry to overcome current reliance on commercial data and to enhance the scalability, affordability, and sustainability of VF systems. As plant growth in indoor VF systems is decoupled from natural sunlight, artificial lighting becomes a powerful agronomic lever. Five studies in this research topic investigated how spectral composition and intensity affect biomass production, plant physiology, and phytochemical content across various species. Thoma et al. examined lovage (Levisticum officinale), focusing on rutin content, a healthpromoting flavonoid. Their experiment revealed that a short-duration, high-irradiance UV-B treatment (1 W m -2 ) notably increased rutin content in leaves, particularly two days after exposure. In parallel, green light, especially under high photosynthetic photon flux density (PPFD), stimulated total biomass accumulation. These results suggested that targeted light treatments can optimize both functional quality and yield in medicinal and aromatic plants. In a complementary study, Flores et al. explored how PPFD intensity affects the morphology, pigmentation, and antioxidant activity of Brassicaceae microgreens (green and red cultivars of cabbage, kale, mizuna, and mustard). They found that high polychromatic light intensities (210 μmol m⁻² s⁻¹) increased plant dry weight and leaf phenolic content, while low and medium intensities (120 and 160 μmol m -2 s -1 , respectively) promoted hypocotyl elongation and pigmentation in certain cultivars. The study, conducted in a growth chamber, highlighted the importance of balancing productivity, energy input, and phytochemical outcomes in indoor VF systems.Taking a volumetric optimization approach, Liu et al. evaluated space usage efficiency (SUE) in edamame cultivation within plant factories with artificial lighting (PFALs). Nine lighting combinations, varying PPFD and color temperature, were tested. The most efficient treatment (700 μmol m⁻² s⁻¹ with 5,000 K LED) maximized biomass production while minimizing plant height, thus improving vertical space utilization. This study also highlighted the influence of light quality, particularly the red/blue (R:B) light ratio, on plant morphology and SUE. This work provides a valuable framework for optimizing productivity and infrastructure efficiency in high-density farming setups. Akter et al. further explored light spectral tuning in cilantro (Coriandrum sativum L.) production. The inclusion of far-red light (FR) in the R:B ratio (specifically R3:B1:FR1) led to significantly increased plant height, leaf expansion, and yield. Interestingly, quality and mineral content remained stable across treatments, pointing to the feasibility of plant yield enhancement without trade-offs in nutritional value. In another study, Anum et al. assessed how different R:B ratios (PPFD = 250 μmol m -2 s -1 ) affected two pakchoi (Brassica chinensis L.) cultivars. The results revealed cultivar-specific responses: red pakchoi showed increased pigment accumulation and efficient gas exchange under R2:B1, while green pakchoi benefited nutritionally from R4:B1. The study also found that glucosinolate content, linked to health benefits, was highest under full-spectrum white light. These nuanced responses reinforce the importance of tailoring lighting strategies to species, cultivar, and market goals. Prabhadharshini et al. investigated the cultivation of palak (Indian spinach) in an A-frame vertical hydroponic system, focusing on optimizing growing media and nutrient formulations. The combination of coir pith and vermiculite, along with a balanced nutrient solution (NPK 60:50:60 ppm), yielded the best production results. Furthermore, the study addressed postharvest preservation by demonstrating that refrigerated storage combined with modified atmosphere (6% O₂, 5% CO₂, 89% N₂) packaging significantly extended the shelf life of palak leaves. This integrated approach, encompassing both yield maximization and postharvest quality maintenance, contributes to advancing more circular and wasteresilient urban plant food chains. The economic sustainability of VF was examined by Amici et al., who studied two Italian commercial microgreen farms. Both realities were found to be profitable, with energy costs kept low thanks to digital optimization and efficient lighting strategies. Nonetheless, high start-up costs and the need for skilled labor remain significant barriers. The authors recommend targeted policy interventions, particularly in the areas of renewable energy incentives and certification frameworks, to reduce barriers for new entrants and accelerate VF scalability. From a scientific meta-perspective, Zhang et al. conducted a bibliometric analysis on Pennisetum research spanning from 1970 to 2023. Although not directly focused on VF, their work underscores the growing interest in underutilized species for forage, ecological, and industrial uses. The analysis identified emerging trends in molecular breeding and international cooperation, suggesting potential contributions of lesser-known species to sustainable agriculture, including applications in CEA. In a different study, Mitchell et al. critically examined the social dimensions of CEA. While consumer studies indicated favorable perceptions, the review highlighted a gap in addressing equity, local identity, and inclusiveness. High costs, private ownership models, and limited community engagement hinder the democratizing potential of these technologies. The authors called for the development of research and policy frameworks that integrate education, transparency, and participatory planning to ensure that the benefits of CEA are equitably distributed. Collectively, the studies in this research topic highlight the dynamic, interdisciplinary progress in VF and CEA. They demonstrate clear advances in technical optimization, from light engineering to urban integration, while raising critical questions about equity, accessibility, and long-term sustainability. These twelve contributions consolidate robust empirical assessments, methodological innovations, and systems-thinking approaches, reaffirming VF's potential to supplement traditional agriculture. As cities expand and the climate crisis intensifies, reimagining plant food systems through the lens of VF offers a compelling vision. However, its success will depend not only on technological innovation but also on governance, design, and social priorities, particularly in addressing key research gaps such as standardized impact assessments, improved energy integration, crop diversification, and inclusive socio-economic models. This research topic aims to advance that dialogue, grounded in science, and drive systematic transformations toward more resilient plant food systems.