I have access to 7 acres of scrub land. Can I grow nut trees in Ontario? What about apple trees.
Thank you for this interesting and thought provoking question. Yes we can grow nut trees in Ontario. There are some restrictions due to temperature zone.
Garden yards grow black walnuts which become large magnificent trees but because they produce juglone, a highly toxic substance, nothing grows around them. Could be good in a scrub area. There are varieties of the tree that grow good edible nuts when planted in sandy to clay soil. Black walnut is also native to Ontario. Some varieties to look for are Emma K, Thomas, Weschcke and Bicentennial.
A non native species, Persian Walnut grows in zone 6. Varieties are Lake, Metcalfe, Coble 2.
Unfortunately, hazelnuts do not grow in this area due to disease.
Northern Pecan trees grow in Ontario. One needs two or more trees to produce nuts. Grafted trees produce more quickly than trees grown from seed. Some names to look for are Snaps, Carlson 3, Lucas and Cornfield.
The often used culinary pine nut also grows in Ontario. Korean Pine, Pinus koraiensis, will grow in Zone 2; also Russian Cedar and Swiss Stone Pine.
There is a society of Ontario nut growers which would be helpful reading. https://www.songonline.ca/articles.htm
Apple trees are grown in the Niagara area to great success. Recently I heard that the Collingwood area was not so successful with its apple orchards.
Planting the trees properly will be very important and none of these trees will succeed if they are merely planted and forgotten. There is much to learn however, with the proper cultural practices and integrated pest management system you will see success. Good luck with this project.