i dont know what the barrel of green style is but one time i took a pretty big plastic container and filled it with a bag of good soilless mix. i threw some seeds in and put them under a few fluorescent strips. after vegging about a month or two i put them in flower and they all turned female. i pulled out weak looking ones leaving about 6 plants in there. the one in the exact center of the container took off and turned into an over 5ft tall monster. the other ones didnt get as much light but they grew to about 20 inches each and yielded around 10g each. the 5ft monster yielded about 85 grams. this was done with a 250 hps, 2 2ft t12 ott lights, and 2 42w cfl's.