Ridiculously slow growth, WTF

I have a small grow under 400w. MH. Eight, "8 Miles High" and two "Medijuana". All started at same time, in the same large(2.5' X 4' container pf soil). The "8 Miles" are growing as in past - 3 weeks out they are on 6-7th node, hand sized fan leaves, gorgeous, branching nicely due to some LST training(just bending, no FIM or pinch). The Medijuana's are pathetic - plants are on 3rd(maybe 4th) node, tiny fan leaves(2" across, maybe). They look totally healthy, but if they got a foot tall in three months I would be surprised. I'm almost wondering if there was a mix up on the seeds, which came from reputable place. Anyone grown Medijuana and is it a really slow take-off or is my case isolated?

Do you have fresh air coming in and going out when your MH is on? what medium are you using?

is there enough nutes slow or not growth all could be lack of nutes.