Many plants have natural substances in their roots, flowers, leaves etc. that can alternately repel (anti-feedants) and/or attract insects depending on your needs. In some situations they can also help enhance the growth rate and flavor of other varieties.
Experience shows us that using companion planting through out the landscape is an important part of integrated pest management. In essence companion planting helps bring a balanced eco-system to your landscape, allowing nature to do its' job.
Companion planting is defined as a method of closely planting two different plants to enhance each other’s growth or protection from pests.
There's a dialogue in our FB group about this subject (click icon to go there)
for container gardens
See more YouTube videos on Companion Planting here