Hi all! My tomato seedlings (San Marzano) are about five weeks old, being grown under lights in my apartment, and have recently started experiencing yellowing/purple lower leaves as well as some bizarre shriveling (photo attached).

I have fed them, twice, a very diluted solution of Happy Frog Grow Big fertilizer thinking that this might just be a nutritional deficiency. It doesn't seem to be helping. I also only bottom water once a week or so, when they seem droopy.

Does anyone have any experience/familiarity with this leaf issue? The plants, overall, seem healthy but obviously something is off.