1st Grow. Feedback?

This is my first grow with a make-shift dresser turned into grow closet. They've been growing steadily for about 4 weeks now off of 2 small fluorescent bulbs, i know eventually i'll have to change the lights, but to what kind? I never used, or plan to use nutrients only because i have no idea what i'm doing when it comes to it, can i still have a successful grow without them? Also i need to know what signs to start flowering i should look for. Any good feedback, tips, or constructive criticism is greatly appreciated!!:stoned: