You need to put lots of light(don't even use this thread to ask about lighting, figure it out) above your plants. You also, to change soil, need to uproot the entire mix in the pot and TRANSFER the root-ball to a newly set pot. Mix your mir grow with lots of perilite from the store(you must buy this..and a few more things if you want to succeed so act now or toss that shit, including your soil cuz it all is useless less you put forth a LOT more effort and get this thing fully established).
Lights
Perlite to better mix your MG soil
ventiliation(fan-no duh, and anything else like duct tape etc that you would need to satisfy your plants' ventilation needs)
reflection(anything around the plant and lights must help at reflecting any light back)
oh and water when "It Is Dry" the soil it wet when watered moist when settled and DRY when DRY; this is when you water.
Distance from lights is also important
Seedlings have differences from adults, they do enjoy a more moist environment i believe. Oh, and you Will mess up, sorry.
:hippy::rasta: