Sweet basil is very important in the culinary and pharmaceutical sectors because it contains volatile oils that have a variety of biological functions. Considering the economical costs and adverse effects of chemical fertilizers, attention has been turned to the use of ecofriendly and cost effective alternatives. In this regard, eggshells could be used as a natural calcium source for nutring the medicinal and aromatic plants. Therefore, the aim of this trial was to assess the productivity of sweet basil in response to different application methods of eggshells on sandy soil. In this study, eggshells were added to the soil at rates of 1, 2, and 3 g/pot, to foliage at rates of 0.5, 1, and 1.5 g/L, and to irrigation water at rates of 1, 2, and 3 g/L; a rate of 0.5 g/pot of calcium carbonate also used as a reference. Plants exposed to eggshells at 1.5 g/L foliar spray gave the maximum values of fresh and dry weights herb (172.11 and 23.48 g/plant), carbohydrates (36.74%), crude protein (16.56%), inhibition of free radical scavenging (47.61%), total phenols (15.03 mg/g), total flavonoids (2.87 mg/g), and essential oil contents (1.18% or 27.71 g/100 plants). On the other hand, plants subjected to eggshells at 0.5 g/L foliar spray produce the highest amounts of linalool (76.34%) and oxygenated monoterpenes (83.37%). It may be concluded that the morphological and physiological characteristics of sweet basil plant may be enhanced by eggshells. [ABSTRACT FROM AUTHOR]