Marigolds are more than just a pretty flower to keep around the home in flower boxes. They also make a great companion plant for most plants, although they can be a little rough on tender herbs. Marigolds produce a pesticide that deters nematodes, with some types of marigold this pesticide can stay in the soil for a year or longer even after the marigold itself is gone. marigolds also deter beetles, beet leaf hoppers, and more.
When planting companion plants together, keep in mind that even plants that help one another in other climates, soil conditions, etc. don't always get along, as we post about companion plants, be sure to always know that each garden will vary slightly from another and what works for some may not work in your garden.
What experiences have you had in planting and/or using Marigolds in and around your garden?