To meet the United Nations sustainable development goals (UN-SDGs) and the European Green Deal, plant biostimulants have become a necessity in agriculture. In particular, seaweed-based biostimulants have received a greater acceptance for their several benefits in crop growth and yield. This study evaluates the effects foliar applications based on vegetables and brown algae extract (Ascophyllum nodosum (L.) Le Jol., on grapes and olive yield in two field experiments in the Apulia region known for its modern agricultural sector. In particular, grape-growing and olive production. At harvest, the yield performances were determined. The results highlighted that the crop responses differed in grape and olive orchards. The biostimulant application determined significant increases in bunch development (+ 9.5%) and bunch weight (+10%) compared to untreated control. In the olive orchard, the yield was not significantly influenced by biostimulant application, whereas we observed quality improvement in olive oil in treated plants compared with the control. To better understand the mechanisms behind this difference, the research concludes by suggesting pursuing in-depth studies and high scientific and technical proficiency to determine and optimise the rates and timing of applications.