Photo period and autoflowers. Autos’s & Photo’s are what you’ll see most people refer to them as. Auto’s don’t require any light schedule change, they flower when they want you have no control.
It wouldn’t hurt to put a little aloe on that cut stem, or cover the wound with teflon tape just to keep bacteria out.
From looking at your second pic, it looks like you need a lot more light.
What soil / medium are you using?
What nutes? (fertilizer)
What light? (PPFD / DLI)
There’s a bunch of these guy’s that blow me outta the water, but as an example this is my girls at 7 weeks:
Scroll down to post 357 to see week 8, and post 371 to see how I still have a ton to learn. Then realize, knowing and applying are two different things. 
Edit: Mine are auto’s.