Yesterday i see new yellow leaves (plant 2). I hav...

Hey there so having your cotyledons slowly die and and fall off is normal. However those new "true" leaves should stay, but they are fragile. If you have a 300 light possibly move it up to between 18-24 for this seedling stage. Another possibility is that a plant this young shouldn't need any nutrients for the 1st few weeks if you're using a good healthy rich soil, like the playgron super mix. I'd back off adding nutes but stick with your warm and moist plan. Even a simple clear plastic cup or bottle over the plant would boost that much used humidity. I hope this helps. Happy growing.

Hello @Zeitter1 ! Man don't freak out 😋 your plants are fine and i don't see any browning. But if you don't stop using bio grow they won't be fine for a long time. It is very soon to start using nutrients and if you can raise the humidity at around 75% and the temperature at 28 °C . Wait at least 2 weeks before you use the bio grow. Happy growing! 👊