I am having an odd problem with my basil. I planted some last spring, in large pots, which is doing fine. Later I decided I wished I'd done more, so I went to Trader Joe's and got some big starts, and planted those out in my own large pots as well. The TJ's basil is just getting more and more yellow. I don't know why. The nice green stuff is growing in the same dirt, and the same sun. Is there anything I can do to bring back the green?