1/2 Yellow Leaf Q????

Why is one of my leaves have half yellow half green??? Also leaves tend to be yellowing???



Suggestions??

Check progress here: https://www.rollitup.org/newbie-central/378092-need-help-first-grow-a11.html

Freaky deaky

I cant believe no one has any idea why it did that???? Maybe I should name is stripe or something...lol.