Found some good info almanac.com..
- Some plants, especially herbs, act as repellents, confusing insects with their strong odors that mask the scent of the intended host plants.
- Dill and basil planted among tomatoes protect the tomatoes from hornworms, and sage scattered about the cabbage patch reduces injury from cabbage moths.
Read more tips here
Here's a video that shows how to improve the productivity of your vegetable garden with companion planting: