A field experiment was carried out at Cairo Aromatic Farm found in Farafra Oasis (New Valley) through two growing seasons (2022 and 2023) to examine the impact of different levels of potassium sulfate ( 50% K₂O) fertilization (0.0, 45, 90 and 135 kg/fed K₂O/fed) on the vegetative growth characters (mean plant height, leaf area, number of plants per square meter and herb fresh and dry weights per cut as well as herb fresh and dry weights either per m² or per feddan) of two mint species (Mentha spicata & Mentha piperita). Data showed that all previous traits were significantly augmented with Mentha spicata than Mentha piperita in all cases. Also, such abovementioned parameters were increased with increasing potassium fertilization levels, where, 135 K₂O/fed produced the highest values in all cases. The interaction was significant for all studied parameters in all cases. It is advisable that the combination treatment between high level of potassium with Mentha spicata was the best in this regard.