The present study was conducted under the wooden shade house of the Department of Forestry, College of Agriculture and Forestry, University of Mosul, during the 2025–2026 growing season, to evaluate the effect of biofertilizers on certain physiological and biochemical processes in two cultivars of Pelargonium grown in loamy clay soil.

The results showed that treating Pelargonium plants with biofertilizers led to significant increases in plant height, leaf area, soluble sugar content, chlorophyll A content, chlorophyll B content, and essential oil percentage. The percentages of increase were 68.00%, 26.60%, 3.88%, 8.59%, 5.72%, and 3.96%, respectively.

Furthermore, biofertilizer application played an important role in alleviating the negative effects associated with the activity of antioxidant enzymes (SOD and CAT) in both cultivars of Pelargonium. The reduction percentages were 0.64% for superoxide dismutase (SOD) activity and 1.59% for catalase (CAT) activity.

In addition, plants grown in loamy clay soil exhibited superior performance in most physiological and biochemical traits. The results also demonstrated a clear superiority of the Tea cultivar over the Stab cultivar in most of the studied characteristics.