I agree with Justaguy - test it out! I don't have an answer, but a thought. There are people who don't use pots, but plant in a hunk of compacted dirt. When the roots reach the edge of the dirt, they either just stop, or take a turn back into the dirt. I haven't seen a good explanation of if they do that more because of the light or because of the exposure to the air, or a combination of both. But that might be a clue as to an answer to your question.