Yellow & brown spots in 2nd and 3rd week in coco-perlite nursery cup. What am I doing wrong? Fed until 20% runoff (extra), strained. Smth with roots?

they look good. I don't see what your describing. You also got a seed with 3 cotyledons. They sometimes are weird plants. https://www.reddit.com/r/microgrowery/comments/31ihez/this_odd_seedling_has_3_cotyledons_and_3_true/ I think maybe the feed might be a bit to strong as in the 2nd pic its a very lush green, almost to much. but if it growing well and healthy I would just leave it.

hello mate, if you talking about the very little spot brown on the rigth leaf i think it's nothing to worry about. Probably water drop has fallen and you didn't see.

Those little spots on that 1 leaf could be from a couple drops of water when watering, humidifier mist, or even debris that could of came in contact from opening tent, fans, etc I see no other symptoms and your plant looks really great! Keep doing what you're doing!!!

Yeah don't worry, that just happens if fertilizer hits the leaves from watering. it won't go away but it also won't get worse. Second picture looks very healthy, ready to be transplanted in final pot (: good luck!

Hey there it looks like your dropped a small drop of water on the leaves that had fertilizer in it. Or it's very mild burn from barley over doing the