To investigate the effect of iron chelate spraying on the medicinal plant European borage under water stress conditions, a factorial experiment was conducted in the form of a completely randomized design with three replications under controlled conditions.The investigated factors include different irrigation regimes at4levels(optimum irrigation,mild water deficit stress,moderate water deficit stress,and severe water deficit stress corresponding to irrigation after20%,40%,60%,and80%depletion of available water in the root zone, respectively) and foliar spraying with 9% iron chelate at four levels (concentrations of 75, 150, 225, and 300 ppm) along was with a control (distilled water). The results indicated that the interaction between the investigated factors had a significant effect on morphological traits (stem height, flower number, leaf area, and shoot dry weight) as well as physiological traits (spad, photosynthetic rate, stomatal conductance, and transpiration rate). In general, severe water deficit stress significantly reduced all measured parameters, whereas mild water stress in combination with foliar application of iron(particularly at75ppm)enhanced flower number and flower dry weight. The greatest stem height was observed under the150ppm iron chelate, while higher concentrations (225 and 300 ppm) exerted negative effects under most conditions.Furthermore, the results showed that the foliar treatment with75ppm iron chelate(40.63)under optimum irrigation conditions had the highest spad index and there was no significant statistical difference compared to the statistically with75ppm foliar treatment(39.6)under mild water stress conditions. According to the results of this study, under the conditions of water stress and optimal conditions, the use of75ppm of iron chelate is recommended for the European borage plant.