Dikes could be lower if they are protected against the waves by grassy marshes. But the protective salt marsh grass is struggling, not only due to increasingly stronger waves, but also to the superfood diet of ragworms. These sophisticated gardeners turn inedible, tough grass seeds into succulent, nutritious sprouts in their burrows. These cultivation techniques prevent many seeds from growing into salt marsh vegetation, thus undermining the use of salt marshes for ‘natural’ coastal protection.