Carbo vegetabilis 30x Significantly Affected Cress (Lepidium sativum L.) Seedlings Grown in Calcium Nitrate Solution

Background: The question of the mode of action of homeopathic remedies has not been resolved yet. Bioassays with plants sensitive to homeopathic remedies can provide valuable tools for examining this topic. We therefore aimed to establish a reliable, quick, and easy bioassay with garden cress ( Lepidium sativum L.) treated with the homeopathic remedy Carbo vegetabilis 30x as the basis for future investigations on the effect of homeopathic remedies. Methods: Cress seedlings were grown upright on chromatography paper in hanging plastic bags and stressed with calcium nitrate solution (0.5 g/L), which increased shoot length and decreased root length in comparison to pure water. Cress was treated with dissolved globules of Carbo vegetabilis 30x or with dissolved unimpregnated sugar globules as a control or left untreated. After a growth period of 5 days at 14.5°C, the bags with the seedlings were scanned, and the length of the seedlings was analyzed using a digital tablet with ImageJ. Outcome parameters were shoot length, root length, total length, and root-to-shoot ratio. Systematic negative control (SNC) experiments were performed to assess the stability of the experimental system. In total, 12 independent experiments were performed involving around 25,000 seedlings in total. Results: Experiments showed a slight but significant increase in shoot length of 0.05 cm ( p = 0.002) through application of Carbo vegetabilis 30x in comparison with the control. The parameters root length and total length were not significantly affected. The root-to-shoot ratio of the seedlings treated with Carbo vegetabilis 30x was significantly decreased ( p = 0.003). Conclusion: The SNC experiments confirmed that the experimental setup was stable. The data obtained are in favour of a possible effect of Carbo vegetabilis 30x on cress seedlings. This test system can be used in future investigations to examine the mode of action of homeopathic remedies. Keywords: homeopathy, bioassay, cress, plant model Publication History Article published online: 03 February 2026 © 2026. Faculty of Homeopathy. This article is published by Thieme. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany