Well not sure on plant size here, but the lower is where I get my clone material from. I also believe (indoors) that undergrowth that does not get enough light can stress and grow nanners. Regardless the way bottom crap will not provide good medicine, so I usually trim before the flower room. I have not seen this induce stress enough to cause nanners, in fact, I think it makes the top part much stronger and grow healthier.

MIND YOU THIS IS INDOORS in a crowded grow area.