This year I tried sprouting seedlings in a proper grow tent with a real grow light. I did butter lettuce, even. One thing I noticed was that my spouts had almost no stalks at all. I think the stalks get long when they are trying to reach more light, not by getting closer to the light source but just by getting up off the ground out of the shadows. It was the first thing I thought of when I saw these - they look leggy. You might try getting them more direct light.