David Jacke and Eric Toensmier's Edible Forest Gardens (
http://www.edibleforestgardens.com/) goes into this in more depth than any other source Im aware of. you'll have to read some, understand the theory presented and then see the charts at the back of book 2- once you have the basics, the charts will help you create tree-companion planting based on site specific considerations.
if you are in the northern hemisphere, read it now. it will eat your summer days up.
