as far as how many plants per square meter it varies as to how big the plants are before you flower them as a general rule most people use 9 per square meter as it allows for a biger yeilding plant with bigger buds or you could go with or you could go with 36 just rooted and shortly vegged clones or if you don't veg them at all once they root you put them to flower you could pack them in at 81 clones per square meter this last method gives you plants that are nothing more then a single bud useuly nomore then a foot tall unless your useing a pure sativa or a heavy sativa cross which will continue to grow a bit before flowering with the plants vegging a bit then plant in my system useuly end up no taller then 18" with a nice big top cola and a few side buds thats for the 4 at per foot and with 9 per meter you can have p[lants that are put into flowering at about a foot to 18" inches if there more indica and end up with some nice huge buds and lots of smaller buds about an inch or 2 long. or if you have the space and more or less grow to supply a town with smoke and have loads of money for lighting only put 1 plant per meter so 1 1000 watt bulb covers only 4 plants but have 10 to 12 lights in an area so having 40 huge plants with huge buds everywhere then many decent sized buds probably totaling a pound or 2 per plant depending on strain

so it kind of depends on what way you wanna grow and how many plants you want to tend with i've tried all three and for me i prefer to go with just 9 plants per meter and have some nice huge center buds and some nice cola's from the branch tops and loads of 1 to 2 inch long buds but i useuly only keep 1/3 so the rest helps pay for itself.