Environmental, agronomic and climatic conditions influence the growth and quality of plants. Lavandula officinalis is cultivated for its essential oil production. This study was conducted to investigate the effect of foliar application of boron (0, 2.5 and 5 mg B L-1) and date of harvest (1st of July, 1st of August and 1st of September) on the production of L. officinalis plants and its essential oil as well as comparing the effect of the essential oil at different harvest dates and its nanoform against Sitotroga cerealella. Application of boron at 5 mg L-1 gave the highest increase in vegetative growth and essential oil yield in plants harvested in September. Eucalyptol (18.46–31.14%) was found to be the major compound of lavender oil, followed by (+)-2-Bornanone (21.30-24.41%), then α-pinene (12.76-14.99%) and β-pinene (11.86-13.59%). Eucalyptol and (+)-2-Bornanone increased when the plant age increased and reached their highest relative contents in the plants harvested in September and sprayed with boron at 0, 2.5 and 5 mg L-1. Both α-Pinene and β-Pinene reached the maximum values in the plants harvested in September and sprayed with 5 and 2.5 mg B L-1, respectively. Using nanoformof the essential oil improved the efficiency of lavender oil at different harvest dates against S. cerealella, and it was more effective than their normal formulations. Treatments with higher concentrations of nano or normal formulations resulted in higher percentage of mortality and reduction of adult emergence. The results can to be used for the improvement of L. officinalis production under drip irrigation system in arid and semi-arid conditions.