This document discusses the concepts of companion planting and provides resources on the topic. It defines companion planting as establishing two or more plant species in close proximity so that some cultural benefit is derived. While the mechanisms are not always understood, companion planting is thought to benefit plants through increasing biodiversity in agroecosystems. The document provides a traditional companion planting chart listing compatible and incompatible plant combinations. It also discusses some of the scientific foundations for beneficial plant associations, such as trap cropping, symbiotic nitrogen fixation, and providing beneficial habitats.