keeping them small....

iv seen pictures of a grow room thats shaped like a tanning booth that grows 120 plants an each plant will give about 1/2 ounce. my question is how do u grow so many plants an keep them all so small? the plants were no bigger then 1 foot in height an 1 lovely bud. could any 1 tell me how to keep them so small- i.e when if grown from seed to flower them and if grown from a cutting how long to root them an then veg them? i would like to try a smaller version maybe 20 small 1/2 oz plants if i get lots off info first. any help would be greatfull

Look up info on sea of green.
I'm thinking about this for my next grow. I think (key word think) that they start flowering straight from clone to keep them that small. pretty sure you can have staggered harvest which would help me out.
guess I've go some reading to do.

https://www.rollitup.org/general-marijuana-growing/340140-harvested-yesterday-pics.html
^^ follow that link should help... pretty slick SOG grow IMO

Could be autos. Lowryder max out in sog about 14".