my first closet advice

hello

i have a problem .....

my plants are growing too fast

in 2-3 weeks of 12/12 the plats increased in height ftom 10 cm to allmout half of meeter

in the grow room is space for another 30 cm but what do i do after that ?






i have no idea what strayn the plants are
this is my first grow
the lights 1 x philips son-t 250w HPS , 2 x 22w economic lights
all the pots are 2l and i use flower soil
dimensions of the closet HxWxD : 160x120x43cm
from 20 plants i got 17 girls
in the closet are 12 plants right now (should remove some of them ?)

you could top them http://forum.grasscity.com/advanced-growing-techniques/122559-how-fimming-topping-made-easy.html

LST them a little bit if you dont want to top them

LST - what does it means ???

newbie ..... more noob

LST= Low Stress Training

Pretty much just bend your plant a little with some hooks or w/e you want

thank you both