Ornamental plants occupy a distinctive position in modern horticultural systems due to their high economic value, significant physiological sensitivity, and fundamental role in enhancing human quality of life. However, the commercial production of these plants faces substantial challenges, primarily stemming from a heavy reliance on chemical inputs, high water consumption, and pronounced susceptibility to both biotic and abiotic stresses. Zinc, as an essential micronutrient, plays a pivotal role in numerous plant physiological processes, including enzyme activation, synthesis of growth hormones, maintenance of cellular membrane integrity, and regulation of the antioxidant defense system. Nevertheless, the low efficiency and adverse environmental implications of conventional zinc fertilizers in calcareous and greenhouse soils underscore the urgent need for innovative nutritional strategies. The objective of this review is to provide a comprehensive analysis of the role of zinc oxide nanoparticles (ZnO NPs) in enhancing growth, quality, physiological processes, and stress resilience in ornamental plants, while also examining the associated challenges and future prospects of this technology. In this article, published studies related to the synthesis, uptake, translocation, and biological effects of ZnO NPs in ornamental plants were systematically reviewed and analyzed. Various synthesis methods (physical, chemical, and biological), uptake pathways (root and foliar), and the underlying physiological and biochemical mechanisms of action of these nanoparticles were investigated. Characteristics such as nanoscale size, high specific surface area, effective penetration capability, and the sustained release of zinc ions render ZnO NPs a promising alternative. Research findings indicate that the application of ZnO NPs at optimal concentrations can lead to significant improvements in vegetative growth, increased chlorophyll content, enhanced aesthetic and flowering quality, a strengthened antioxidant system, and greater tolerance of ornamental plants to abiotic stresses such as salinity, drought, and temperature extremes. These effects are primarily attributed to increased zinc bioavailability, regulation of pigment metabolism, reduction in reactive oxygen species (ROS) accumulation, and modulation of hormonal pathways. However, the response of ornamental plants to ZnO NPs is dependent on concentration, application method, the physicochemical properties of the nanoparticles, and plant species. Excessive application may induce phytotoxicity, bioaccumulation, and metabolic disorders. Therefore, while ZnO NPs hold considerable potential as a novel and efficient zinc source for the sustainable production of ornamental plants, determining optimal concentrations, elucidating the molecular mechanisms of action, and evaluating long-term environmental impacts are essential prerequisites for the safe and widespread commercial adoption of this technology.

Overall, ZnO NPs show significant potential as a sustainable and efficient zinc source for ornamental plant production. Yet, determining optimal concentrations, understanding molecular mechanisms, and assessing long-term environmental impacts are critical for safe, effective, and widespread commercial application of this technology.