This study investigates the impact of four different biostimulants—Eklonia maxima, Ascophyllum nodosum, fulvic acids, and protein hydrolysates—on the growth and yield of rosemary (Rosmarinus officinalis L.) in an organic agricultural system. The results show that the application of biostimulants significantly improved plant performance compared to the control (water). The highest fresh and dry biomass yields were achieved with fulvic acids and protein hydrolysates, which were 60% higher than the control. Protein hydrolysates also produced the highest essential oil (EO) yield (66.5 kg ha⁻¹), while fulvic acids resulted in the lowest EO content (1.14%) but the highest EO yield (65 kg ha⁻¹). The study highlights the effectiveness of biostimulants in enhancing rosemary growth and EO production in organic farming systems. The application of biostimulants improved various morphological and productive parameters, including plant height, stem diameter, chlorophyll content, and relative water content. The study also found positive correlations between plant height, chlorophyll content, and EO yield, indicating that biostimulants can enhance the overall productivity and quality of rosemary. The findings suggest that biostimulants are a valuable tool for increasing yield and improving the quality of rosemary in organic agricultural systems.This study investigates the impact of four different biostimulants—Eklonia maxima, Ascophyllum nodosum, fulvic acids, and protein hydrolysates—on the growth and yield of rosemary (Rosmarinus officinalis L.) in an organic agricultural system. The results show that the application of biostimulants significantly improved plant performance compared to the control (water). The highest fresh and dry biomass yields were achieved with fulvic acids and protein hydrolysates, which were 60% higher than the control. Protein hydrolysates also produced the highest essential oil (EO) yield (66.5 kg ha⁻¹), while fulvic acids resulted in the lowest EO content (1.14%) but the highest EO yield (65 kg ha⁻¹). The study highlights the effectiveness of biostimulants in enhancing rosemary growth and EO production in organic farming systems. The application of biostimulants improved various morphological and productive parameters, including plant height, stem diameter, chlorophyll content, and relative water content. The study also found positive correlations between plant height, chlorophyll content, and EO yield, indicating that biostimulants can enhance the overall productivity and quality of rosemary. The findings suggest that biostimulants are a valuable tool for increasing yield and improving the quality of rosemary in organic agricultural systems.