Companion planting in garening and agriculture is planting of different crops in close physical proximity, on the theory that they will help each other. It is a form of polyculture. Companion planting is used by farmers and gardeners in both industrialized and developing countries. Many of the modern principles of companion planting were present many centuries ago in the cottage garden. Although there is a wealth of information on its historic use, there remains limited available scientific research on the effectiveness for each of these interventions.