I read an interesting article in PopSci (the online version of Popular Science) about “pest repelling plants.”
The article had different plants for each region of the country, and while it promised that many of the plants were perennial, I found that those recommended for the “North,” were not. I also found that those recommended for other regions (the Midwest, for example) would work equally well in my garden, and some of those were perennial.
The basic premise of the article was that certain plants attract insects and will therefore keep those insects from other plants. I am not sure that I call that “pest-repelling,” but hey, whatever works.
They did mention marigolds as repelling nematodes and garlic for repelling rodents. I am not sure about the garlic, never having grown it. I do grow the catnip they recommend and while I cannot be sure about the mosquito and fruit fly (?) (do I even care about that outside? And why?), I can tell you that catnip has worked as a wonderful Japanese beetle repellant for me in a bed of roses. In fact, since I have planted catnip, I have no more Japanese beetles in my yard at all. Coincidence or cause and effect–I am not sure but I will take it!
Another of the plants they recommend (for the West) is nasturtiums. They say that they attract beneficial wasps and repel squash borers and whitefly. I suppose that their effects could be entirely different in different parts of the country but for me I have always found that they are aphid magnets. I have never particularly liked this effect, but if you have plants that always have aphids, you could try nasturtiums as a trap crop, I suppose. I like to grow them to eat, and I don’t enjoy eating aphids!
In any event, the article is fascinating and a great example of “working smarter, not harder” in the garden. I am always a fan of that, as I am a fan of gardening without pesticides. Definitely check it out! You might find some ideas that work for you.
Gardendaze 
Plants that attract pests away from more desirable plants are old technology, so must be effective. It makes little sense to me though. In the old vineyards of Paul Masson, overgrown roses grew at the ends of some of the rows of grapevines, supposedly to attract pests away from the roses. (I believe that the technique was used only for particular cultivars of grapes, since the majority of vineyards lacked roses.) The roses could be sprayed with non selective insecticide to kill the pests, without spraying the grapevines. I sort of get it. However, the technique also kills predatory insects, such as green lacewing and ladybug, that also lived on the roses. Also, pests that afflict roses are not the same that are interested in grapevines.
Oh no, I am not a fan of that sort of thing at all. Non-selective stuff does kill off more good things than bad–the way I describe it when I lecture is it’s like taking an antibiotic for something ridiculous–say a hang nail. You do far more damage than good.
That’s why even with the “organics” we need to be so careful. Even insecticidal soap or Neem is non-selective. You can’t spray if bees are around.
Karla