This pretty much answers your question
Super Cropping - SOG Style
Welcome soggers to the wonderful world of supercropping. Though it may seem somewhat cruel and evil to abuse one's children, I assure you that such things are permissable and encouraged if your children happen to be pretty female flowers.
I recommend High Times' "Best of" issue for 2001 for an excellent pictorial demonstration on how supercropping is done.
I'll do the best I can to explain it in words:
Supercropping is based on a pretty simple principle: strong plants will become stronger if forced to endure certain types of stress. In this case, that type of stress is breaking the inner husk of the meristem (In SCROG you would be breaking a number of branches, not just the meristem). Once broken, the husk is given a week to recover in which time the stem becomes thicker, growth becomes more vigorous, nutrient uptake increases, and bud size as well.
If you notice the photos above, the large skunk plants were vegged for 7 days in 4" rockwool cubes and the colas are obviously quite large. In fact, they are very large for plants that were only vegged for seven days in 4" cubes, and those pics were taken at 50 days 12/12 so you can imagine how large they were at 70 when harvested. It was an initial experiment with the supercropping method, and more intensive treatments would surely produce even more pronounced effects provided adequate support was given (see below).
Technique and timing is crucial, but it's really quite easy if you know how. After clones have established themsleves in the 4" cubes you begin.
First treatment should occur on the meristem beneath the top grow shoot. To break the husk, you simply pinch the stem in between your thumb and forefinger (like a spliff) and gently crush it while simultaneously moving your fingers in opposite directions (just like break up a small nug of dry sensi). It is good to gently bend the cutting over so that the injury becomes more pronounced and the clone wilts. Remember in my first installment, I suggested placing bamboo poles in the cubes when transplanting. Well they come in really handy at this point and will throughout the supercropping experience.
You will notice much more vigorous growth over the next few days, and the cuttings will really begin to take off. After the initial wound is healed, and several new leaf nodes have grown (best rule is when growth has doubled) you may resume the process, this time working larger areas between the nodes, and leaving about 2" space between each break. I like to vary it quite a bit, making fairly large 3" wounds, and then several smaller breaks. Remember to give adequate recovery time for best results.
You may wonder if you have to change the technique once the plant gets larger, and my answer is yes and no. You continue to pinch and twist the stem, but you also have to listen for the sound of the husk breaking to make sure you're doing adequate damage. Practice makes perfect. It's really not that hard, and you'll catch on pretty quick. You'll also find that even severe damage can be done to the stems without affecting growth (as long as you are supporting it properly so that it is not strangling itself), and will in fact increase bud weight in the end. Some of the largest colas I've seen have had horrible-looking wounds all the way up the meristem. The key is to providing a proper environment for recovery by giving them adequate time, using support, keeping food and environmental conditions at optimum levels.
Also remember to re-break already broken areas once they have fully healed.
When flowering is initiated and the girls begin to stretch, you should work every several inches up the meristem making large and small wounds. Not all the breaks should be equally traumatic. Try to keep it to one or two severe breaks each treatment. The B1 I recommended in my last post will help a lot in the early days of flowering. Your girls will just love it (sort of). You can probably up your food levels to 1800EC right after you go to 12/12 since they will be eating A LOT to recover (like a bodybuilder. A bodybuilding plant, I wonder if you can give your plants Deca?)
The treatment is to be repeated until 3 weeks into bloom. You will be pleased with the results. Also note that additional support may be necessary since the top colas of these supercropped plants become so large that the rockwool cubes cannot support their weight and they tip over creating a horrible mess. One friend's grow had to be harvested a week early because of such a tragedy. Packing Hydroton or rockwool between your cubes might help keep them supported. The panda film also helps to keep the cubes in their place. If you wanted to get fancy some reinforced chicken wire would be solid. This would also help to keep your profile in check during the stretch.