I think I am killing them

[Talon1189]

I am a newbie growing from seed. I have been growing the 4 week old sprouts in miracle grow potting mix. I potted up from an ice cube tray last week to a 3 1/2 in pots. I mixed in 2 heaping teaspoons full of an all organic 7/4/5 into each pot. I have read since then that fertilizer while potting up is not a good idea in general I have 3-4 out of my 15 plants turning brown on their leaves then folding over for probably death. I have like 6 plants still in the ice cube trays that are growing 4-5 inches tall but are lanky but look healthy to me. I want to transplant them to the 3 1/2 inch pots within 2 days to help cover the dieing plants. What are your opinions.......Sorry I have no pictures