Garlic powder actually works well for bugs, it's pretty cheap, and will not steal any nutes from your plants growing area. Also putting worm castings & bat guano around the base of your plants, mixed in with the topsoil keeps away a varity of bugs as well. Not to mention, they are great fertilizers.
.
I have never used Marigolds, since they are brightly colored & would draw attention to Mary. Green among green - is rarely seen.
.