List of companion plants

This is a list of companion plants, traditionally planted together. Many more are in the list of beneficial weeds. Companion planting is thought by its practitioners to assist in the growth of one or both plants involved in the association. Possible mechanisms include attracting beneficial insects, repelling pests, or providing nutrients such as by fixing nitrogen, shade, or support. Companion plantings can be part of a biological pest control program. A large number of companion plant associations have been proposed; only a few of these have been subjected to scientific testing. Thus where a table column for example states "Helps" or "Helped by", this is to be read as meaning that traditional companion planting involves putting the named plants in that column into an association with the plant named at the left of the row, with the intention of causing the one plant to help or be helped by the other. Mechanisms that have been scientifically verified include using strongly aromatic plants to deter pests; using companions to hide crops from pests; providing plants as nurseries for beneficial insects including predators and parasitoids; trap cropping; and allelopathy, where a plant inhibits the growth of other species.