<p>Asarum is a perennial medicinal plant that faces significant challenges associated with continuous cropping during its cultivation. The incorporation of external carbon and nitrogen sources has proven to be an efficient strategy for mitigating these continuous cropping obstacles. In this study, biochar and acid hydrolyzed casein (AHC) were employed to enhance the growth of Asarum and improve soil quality, thereby alleviating ongoing cropping barriers. A pot experiment was initially conducted to investigate the optimal ratio of biochar to acid hydrolyzed casein, followed by an assessment of the short-term effects of these external carbon and nitrogen sources on various soil physicochemical properties, soil enzyme activities, soil quality indexes, plant phenotypes, and plant defense enzymes. Results from both pot and field experiments demonstrated that the application of external carbon and nitrogen significantly influenced both soil characteristics and plant performance, significantly increasing soil pH and organic matter content as well as enhancing activities of acid phosphatase and urease while improving overall soil quality index. The pot experiment revealed substantial enhancements in plant phenotypic traits, physicochemical attributes, and defensive enzyme activity. These findings indicate that short-term application of carbon and nitrogen can markedly stimulate Asarum growth under continuous cropping conditions; furthermore, this increase in Asarum’s growth correlates directly with improvement in soil quality facilitated by using carbon and nitrogen sources. These findings provide a scientific foundation for promoting the growth of medicinal plants while addressing ongoing challenges related to continuous cropping.</p>