This study was conducted to determine the effects of Artemisia sieberi extract (0.2%, 0.4%, and control) on germination, some morphological characteristics, photosynthesis pigments, and nutrients uptake of Peganum harmala. Results showed that the extract of A. sieberi had a significant effect on seed germination and morphological characteristics of P. harmala. The highest seed germination was calculated in 0.2% treatment. The lowest seed germination was observed in the control treatment.The highest and lowest radicle lengths were calculated in the control and 0.4% treatments, respectively. With increasing concentration of the extract, dry weight and pedicel length of P. harmaladecreased. A. sieberiextract had phytotoxic effect on chlorophyll contents of P. harmala. The highest photosynthesis pigments were related to the control treatment, and by increasing the concentration of extract, photosynthesis pigments decreased. The highest contents of nitrogen and zinc were found in 0.2% treatment. The lowest amounts of nitrogen and zinc were related to 0.4% treatment. The highest amount of phosphorus was related to the control treatment and with increasing concentration of extract, phosphorous content decreased.0.2% treatment exhibited the highest potassium content while the lowest amount of potassium was related to the 0.4% treatment. In general, results showed that A. sieberibesser, increased nutrients uptake of P. harmala, in 0.2% treatment, but increased concentrations of the extract prevented germination and growth of P. harmala. It is recommended not to cultivate the two plants together if we considerP. harmala as a medicinal plant. Manuscript profile