The current increase in energy demand, along with the deepening climate crisis, has led to the need for alternative energy sources. One of these is the cultivation of energy crops. In turn, issues related to the deepening problem of soil salinization are an important aspect of environmental protection on a global scale. New species and innovative solutions are sought to support the effective cultivation of energy crops, including in saline areas. The purpose of the study was to evaluate the effect of the foliar application of an aqueous quercetin solution applied in different doses (1%, 3% and 5%) on the physiological properties of Virginia Mallow plants subjected to salt stress conditions. The experiment was carried out as a pot experiment. The results obtained were related to two types of plants treated as a control sample. In one case, they were grown with the addition of quercetin alone, without salt stress. The other group was grown without quercetin and without salt. Quercetin is a phenolic compound that plays an important physiological and biochemical role in plants. Salinity caused a significant decrease in physiological indices in Virginia Mallow leaves. Foliar application of an aqueous quercetin solution mitigated the negative impact of salt on plants, the most stimulating effect being demonstrated at a dose of 5.0%.