Series of field experiments with Mediterranean herb oregano (Origanum vulgare L.) in Central European climate

This study presents the first report in a series of field experiments investigating oregano ( Origanum vulgare L.) under variable weather conditions in the Carpathian Basin. The three-year trial was designed to determine optimal harvesting time and plant density. A dataset comprising more than 4000 individual observations was evaluated, providing a robust basis for the derivation of well-supported conclusions. Ongoing climatic shifts, particularly the occurrence of milder winter periods, suggest that oregano can be successfully cultivated in Central European environments, achieving yield performance comparable to that observed in Mediterranean regions. The application of a 75 cm inter-row distance, combined with a 30–40 cm intra-row plant spacing resulted in essential oil yields over even 250 dm³ × ha⁻¹ . Optimal harvest timing was identified at the onset of full bloom, corresponding to the highest essential oil concentrations (2.1–2.5%). Furthermore, heat sum and precipitation sum were found to exert a significant influence on the yield-related parameters. Relative to the first experimental year, plant height, dry weight and essential oil yield decreased in the subsequent, arid year by 20%, 31%, and 34%, respectively. In contrast, during the third year, characterised by higher precipitation, plant height, dry weight, essential oil concentration and oil yield increased by 172%, 270%, 102%, and 282%, respectively. The relative composition of several volatile constituents in the essential oil including the dominant compound carvacrol was not significantly affected by plant density or harvest timing. Carvacrol exhibited considerable variability, ranging from 7.4% to 86.6%; however, its proportion exceeded 60% in 105 out of 128 samples. A moderate correlation was identified between essential oil concentration and carvacrol content. The chemical profile of the investigated oregano met the quality requirements of the processing industry. • Oregano can be considered as drought-tolerant but not as drought-loving species. • Inter-row distance of 75 cm and intra-row distance of 30–40 cm are recommended. • Harvesting should take place at beginning of full bloom for the highest oil yield. • Medium correlation was calculated between the essential oil and carvacrol content. • Theoretical oil yield production of oregano is higher than 300 dm 3 × ha −1 in Hungary.