My experience with marigolds is they attract slugs so when cooking we keep all the egg shells all year long in a bucket and we crush them and pour the shred on the soil when we plant the tomatoes and others : slugs hate crawling on shredded egg shells. Then, before the sun gets down, I take my shears and go behead any slug approaching the vegetables for a night snack, the ones coming later will focus on eating their cadavers. Slugs really are a pest.