Optimizing vineyard floor management can enhance carbon sequestration and mitigate greenhouse gas emissions. Yet, the net effects of sowing cover crops, particularly when combined with soil tillage, remain uncertain in viticultural systems. This study assessed the short-term impacts of three inter-row practices: spontaneous vegetation (Control), cover crops sown after conventional tillage (Till), and cover crops sown without tillage (Sod-seeding), on soil-plant system CO2 fluxes and carbon inputs in two commercial vineyards in South Tyrol. Soil-plant respiration was quantified using continuous, automated chamber measurements and survey campaigns throughout the season, while above and below-ground biomass sampling provided estimates of carbon stocks. Tillage before sowing triggered pronounced pulses of soil CO2 emissions at both sites, substantially increasing daily carbon losses compared to Sod-seeding and spontaneous vegetation treatments. In contrast, Sod-seeding and Control plots maintained lower and more stable respiration rates. Biomass responses varied by site: at one vineyard, tilled cover crops enhanced above-ground biomass relative to spontaneous vegetation but reduced root carbon stocks, whereas at the other site, no significant biomass differences were observed. We concluded that elevated soil CO2 emissions following tillage could offset potential gains from increased aboveground productivity. Sowing cover crops without tillage avoided respiration peaks and, at one site, enhanced total plant carbon inputs compared to the Control. These findings suggest that replacing spontaneous vegetation with sown cover crops does not consistently improve short-term carbon sequestration, referring to the seven-month experimental period from mid-October 2024 to mid-May 2025. The present results highlight that the effectiveness of regenerative soil management in mountainous vineyards remains strongly site-dependent, underscoring the need for long-term evaluations of net ecosystem carbon balance beyond a single growing season.