In this study, mullein plant (MP) (Verbascum Thapsus) was replaced with cement at a dosage of 300 (the amount of cement in mortar for producing 1 m3 mortar) in cement-based mortars at different weight ratios (0%, 1.5%, 3%, 4.5% and 6%). To investigate the impact of MP on the hydration (internal) temperature and the formation time of hydration products in mortars, the mortars' interior temperature and moisture ratios were measured and recorded every minute for one day. It was concluded that the MP had a high-water absorption capacity and delayed the initial and final setting times. The optimum ratio of MP as a replacement for cement was found to be 1.5%. The study also investigated the effects of direct current (DC) application on fresh mortars (both with and without MP). The results showed that the 7-day mechanical strength of the reference mortars exhibited a significant increase with the application of DC. Previous studies have not explored the use of MP in cementitious composite materials. This study concluded that adding a specific amount of MP to cement-based materials can provide self-curing and self-cooling properties. This research is critical for water conservation as it develops a novel self-curing method.