I know everyone digs holes and mixes in all sorts of good stuff for the plants to grow in. My question is how much do the plant's roots venture out of this good soil. To what extent to they get 'pot bound' around the unturned natural dirt? Do the roots just keep going down into the rocky dirt?
Roots will continue to spread out as long as the plant is alive. They will go through just about any substance during their search for food and water.
So in theory, if the soil was naturally good quality I could plant directly into the ground without mixing anything else in?