What is the correct term used for growing different types of plants together?

Companion planting, I think.

graft 1. Horticulture.
a. a bud, shoot, or scion of a plant inserted in a groove, slit, or the like in a stem or stock of another plant in which it continues to grow.
b. the plant resulting from such an operation; the united stock and scion.
c. the place where the scion is inserted.