This study was performed during the winter seasons of 2022 and 2023 to examine the effect of irrigation water treatments (magnetized and non-magnetized), foliar applications (humic acid, seaweed, yeast, and garlic extract) and their interactions on vegetative measurements, seed yield, oil productivity, and essential oil constituents of black cumin (Nigella sativa L.). All plants under the different foliar applications treatments received half of the required quantity from mineral fertilizer (NPK) compared to the control treatment (full recommended dosage of NPK). According to the results, the plants watered with magnetized water in both seasons showed the highest significant levels of essential oil constituents, oil output, seed yield, and vegetative growth when compared to plants irrigated with untreated water. When comparing the effects of foliar treatments, garlic extract at 5 g/L had a superior effect on all of the aforementioned factors. Thus, both previous treatments, magnetized water and foliar spraying with garlic extract at 5 g/L in interaction, succeed to record highest values for some traits under study, such as seed yield, volatile oil production, and essential oil constituents without significant difference between magnetized water with full recommended dosage of NPK (control). This might be suggested to enhance black cumin plants, particularly in terms of seed yield and volatile oil output with premium essential oil ingredients, in order to lower production costs, lessen environmental pollution, and safeguard public health.