jcf1,i had a plant like this and could Not work out what was wrong,SO i transplanted her ,nearly lost her while she was settling,but now weeks later shes one of the top 5 in crop of 35.This is Outdoors, but my point is that tho i couldn't figure out problem then,AFTER transplanting the main thing i noticed was that the TAP ROOT had been blocked off by a rock of clay!!She's nice N dark now and 1 week into flowering,hope i broadened ya horizons at least...cheers V
