well your off to a much betta start with the attitude as for yeild from a single plant with 250w hps in soil can range anywhere from -0(worst case senario plant ends up being male then ur stuck with a bunch of ballsacks an nutjuice aka pollen)to 50grams per watt which is very unlikely unless your injecting raw fishscale coke into the stem...anywayz a realistic yeild for an alright grow would be about .5 to 1 gram per watt and thats optimistic at best depends on how long your vegging what your vegging under what your feeding and how much time and money you invest i myself am growing with 250w hps my tomatoes are looking good but then again ive already done process of elimination with all the males and am left with 2 females which are in flower and have taken several clones from each which is what i'd recomend get as many female clones as u can to make sure u dont totally fuk shit up and get ya hands dirty expect nothing that way what ever you gain is more then what u want(which u should be thankful for all the wisdom u gain in experience even if u end up with a joint and some hemp paper)..anywayz safe growing and by the way ur a fuken cunt..