dont worry about the height,abundent light,good nutrients,will give you a short compact healthy grow,like yours,obviously the roots are doing well,or else they would not be as bushy as they are,another week or so they'll be ready to flower,and since their short,you're going to get quite a few good bud sights exposed to and recieving a lot of light,and they will end up at around 18-24",i think you're going to get a heavy yeild from each plant,are those cuttings or a seed grow?it looks excellent so far,whatever you're doing it's working,you can keep a 600WT lamp about 18" from the top of the canopy throughout the rest of the grow,and keep a fan going on them at all times....bonbon