Ok, I have one plant about 3-4 weeks old in a terra cotta pot that I keep outside. Some time ago, we had a cold night (about 49-50f) and the stem, which was about 2 inches long at the time turned a bit reddish. The stem doesn't seem to be getting much bigger, and the plant is starting to seem top heavy. I watered it today and it tipped over from the weight. It's leaves are fine and seem to be growing steadily but the stem is worrying me. The redness has faded a bit but it seems like the stem should be much thicker by now. It is still only about as thick as a pencil lead, if that. Suggestions?