Ok, you said pro mix and youve never given any fertilizer. Heres what you need to do. Find yourself a fertilizer. Then do some reading into pro mix and pro mix feeding shedules with your fertilizer. Pro mix has no nutrients in it like i said so your starving them in a really bad way. If you start asap the ones that look really bad should come back around and you could salvage somthing from the work youve put into them.