Tagetes is a genus of annual or perennial, mostly herbaceous plants in the family Asteraceae. They are among several groups of plants known in English as marigolds.
If you are planting French marigold seeds indoors, they need a warm area. Seeds need a temperature of 21-23 C. to germinate. Once the seeds are planted, it takes 7 to 14 days for the plant to pop up.
Once established plant around your slug sensitive plants and it will work as a bait to attract them and distract from your food crop. You can collect and dispose slugs in your chosen manner. Very effective. At the same time great pollinators flower.