Restoration of riverbanks through soil bioengineering techniques allows managers to combine riverbank stability and riparian ecosystem functioning. This restoration often involves the sowing of a seed mixture, which helps develop herbaceous vegetation. This development and sufficient vegetation cover are essential for protection against erosion and for hosting biodiversity, two of the main goals of riverbank bioengineering. Restoration aims at recreating ecosystems closer to an undisturbed state; choosing seed mixtures of local provenance is therefore encouraged. In this study, we investigated the local seed mixture sown on bioengineered riverbanks and the conditions influencing the first steps of plant development, so as to delineate the setting favoring restoration. We focused on the composition of the seed mixture and germination capacity as well as the effect of sowing density and soil quality on vegetation cover and diversity. We tested four sowing densities: 5,10, 15, and 30 g.m