The most important book on Forest Gardening for Northeastern North America (including Ontario) is the two volume Edible Forest Gardens by Dave Jacke and Eric Toensmeier.
Martin Crawford’s books are also an excellent introduction to the field, though more focused on the climate of the UK.
Gaia’s Garden, by Toby Hemenway is also a great introductory volume, though a bit more suited to Western North American growing conditions.
Mark Sheppard’s Restoration Agriculture takes a more large-scale approach, and includes animals in the systems he describes.
There are numerous other excellent books listed here.
In Southwestern Ontario, training in Forest Gardening is available through the Living Centre.
Sources for Plants
Included below are some of the best sources for plants for forest gardens for those living in Southwestern Ontario.
Artemisia’s Forest Garden Nursery – Edible, medicinal, and useful plants. Pick-up only (near London, Ontario).
Fiddlehead Nursery – Specializes in edible landscapes and Forest Gardens. Pick-up only (near Kimberly, Ontario).
Whiffletree Farm and Nursery – Vast selection of fruit and nut trees, shrubs, and vines, almost all suited to Forest Gardens. Mail-order.
Grimo’s Nut Nursery – Many grafted and layered nut trees and interesting minor fruits. Mail-order.
Rhora’s Nut Farm and Nursery – Good selection of nut trees, and minor fruits. Mail-order.
Richter’s Herbs – Outstanding selection of medicinal herbs, many of which are suitable for Forest Gardens. Mail-order.