AbstractBACKGROUNDApplying organic amendments to vineyard soil improves soil properties and vine development by increasing soil water retention and nutrient content. However, little is known about how organic mulches modify grapevine phenolic composition. This study analysed the phenolic profile in the leaves, canes, and grape skins of Tempranillo over 3 years in two vineyard locations with three organic mulches: spent mushroom compost (SMC), grapevine pruning debris (GPD) and straw (STR), as well as two conventional soil practices: herbicide (HERB) and tillage (TILL).RESULTSSeventy phenolic compounds were identified and quantified in leaves, canes and grape skins. The phenolic biosynthetic accumulation differed among the soil management practices according to field conditions. In nutrient‐deficient soils, the nutrient‐rich SMC mulch enhanced plant nutrition resources for primary metabolism, reducing the phenolic accumulation in grapevine tissues. However, this behaviour was not described in a non‐limited soil nutritional content. The GPD and STR mulches, with slow decomposition rates, slightly differed from conventional practices and could have a long‐term effect on plant phenolic accumulation. Despite the variations observed between soil treatments, the grape phenolic profile did not change enough to affect the grape quality significantly.CONCLUSIONSThis research represents the most detailed study on the impact of organic mulches on the phenolic profile of grapevine tissues. These findings suggest that organic mulches in vineyards constitute a viable alternative for soil management, benefiting both soil physical and chemical properties and plant development without altering the grape quality. © 2025 Society of Chemical Industry.