Treatments included a vegetal-derived protein hydrolysate (VPH), free Cu (from copper sulphate), Cu complexed with vegetal-derived peptides (Cu-VPH), and a combination of VPH and Cu-VPH (VPH+Cu-VPH). Foliar treatments began seven days after transplanting and involved five distinct treatments: 1) copper (58.5 mg/L); 2) VPH Trainer® (Hello Nature, Rivoli Veronese, Italy) (4 ml/L); 3) Cu-VPH Scudo® (Hello Nature, Rivoli Veronese, Italy (0.5 ml/L); 4) VPH (3.7 ml/L)+Cu-VPH (0.5 ml/L). Except in VPH treatment, copper concentration in foliarly applied solutions of all treatments was 45 mg/L. Untreated control served as comparison group. Foliar applications were repeated every week. The results are summarised in Figure 1. The results of the study revealed a significant accumulation of secondary metabolites, particularly alkaloids, terpenoids, and phenylpropanoids, in response to Cu treatment. Indeed, the higher content of these metabolites served as a protective mechanism against oxidative stress-induced damage, indicative of the plant’s response to unfavourable environmental conditions. In contrast, Cu-VPH treatments exhibited lower levels of these stress-related compounds, indicative of a healthier plant phenotype with reduced ROS levels and oxidative damage. However, both Cu and Cu-VPH treatments led to higher Cu levels in plant tissues compared to control. The Cu-VPH treatment regimen while still inducing significant alterations in transpiration rates and reduced water use efficiency (WUEi), maintained high leaf nutrient levels (Ca, Mn, Fe), photosynthesis and fresh yield showing a trade-off between nutrient uptake and water conservation strategies. The VPH treatment enhanced the Electron Transport Chain (ETC) activity, thereby promoting more efficient photosynthesis and ultimately leading to increased yield. Additionally, it boosts the uptake of essential minerals such as calcium (Ca), manganese (Mn), and iron (Fe), further supporting plant growth and health. The VPH+Cu-VPH treatment regimen determined a significant increase of morpho-physiological and biochemical characteristics compared to other approaches. In fact, this treatment significantly improved the plants’ carboxylation activity (ACO2) and maximum potential quantum efficiency of Photosystem II (Fv/Fm), suggesting an optimized Cu utilization. Interestingly, the combined treatment also led to higher levels of other essential ions, such as Mg, Mn, Ca and Fe, crucial for chlorophyll formation and photosynthesis. The improvement in nutrients use efficiency enhanced fresh basil yield, highlighting the effectiveness of the VPH+Cu-VPH treatment approach. The VPH+Cu-VPH combination also resulted in a notable increase in tryptophan content, accompanied by inhibition of stem elongation and promotion of plant compactness. These morphological alterations contributed to an overall improvement in yield, suggesting a synergistic effect between VPH and Cu-VPH treatments on basil growth and development. The study highlights the potential of combining Cu with biostimulants like VPH to increase crop yield and nutrient use efficiency. By enhancing Cu bioavailability and alleviating oxidative stress, these combined treatments offer a sustainable approach to improving crop productivity while minimizing environmental impact. This research underscores the importance of innovative techniques in promoting agricultural sustainability and addressing the challenges of modern farming practices.