I have topped my indica plant, but my gf is growing a Sativa and she refuses to top it. she asked why you top it. I told her bassically it makes the nugs more compact and heavier in areas if you do top it. If you don't thank you have smaller nugs all over the plant. But she doesnt really understand and I don't really know how to explain it to her better. Im going to show her this when she comes home from work. So could you guys help me out?
If you want to keep the plant more bushy and increase larger bud sites then topping is a very nice solution. Topping once will result in two main growths at the top of the plant, instead of one. It can be done multiple times as well. I had great results with my outdoor plants. Check out the topping tutorial: http://forum.grasscity.com/plant-training/122559-how-fimming-topping-made-easy.html
Topping your plant will make it bush out. The other main reason I top is to even out my canopy in ScroG. ScroG makes it possible to get near equal amounts of light to EVERY budding location, and with that being said your yields have the potential to be larger if you top, train, and ScroG. The last reason I have heard of people doing it is just because they don't like the one, big main cola. They like to top and train so that all of their buds are consistent in size and weight. It also can reduce the 'popcorn' nug factor. Hopefully you will try topping, and maybe someone can get in your thread and be more technical than I was. - SwetnK
My cabinet only allows for 36 inch finished plants so I remove the tip of the buds until the main stalk has 8 top buds and the two first side buds on the main stalk until each has 4 buds. I do my topping at every third node. When all of my final toppings are fully formed and starting to open I move them into flower and the plant is appx 12" to 14" tall. By the time the plant reaches 8 weeks of flowering I sometimes have to bend the 8 buds on the original main stalk down to keep them out of the lights until they finish out. Bending them is easy. Just pick your point on the stem you want to bend and using your fingertips,squeeze the stem forcefully 90 degrees from the direction you want to bend the stem,move around the stem with your fingertips 90 degrees and squeeze forcefully across the first squeeze,now you will be able to bend the stem forward or back to the position you desire. Using sewing thread, you can tie the stem at the desired amount of bend until it "sets" in place. If you don't the stem will try to straighten back up again. After aboit a week you can remove the thread and the plant should stay bent just like you want it.
The last part you talk about is called Supercropping. It is a little more stressful on the plant than other methods, but can be very successful. If you didn't want to supercrop, when you are topping, you could add LST to your grow, and tie down your toppings. Then you can either let the bud sites grow up from there, or add a screen for a scrog and a nice even canopy. Not that supercropping is wrong, I am just adding another option.
Jorge Cervantes has a greet "indoor/outdoor bible" that covers this stuff. You can actually read the topping section on google books. Scientifically, topping redirects plant growth hormones and depending on how you top it will change how the plant grows. Topping the main stalk will cause all of the other branches to grow bigger, and usually cause 2-4 new stalks to form in place of the one that was cut off (depending on where you cut it). I experimented with this 2 seasons ago. Took clones of the same plant, topped half of them and left the other half. Yield on the un-topped plants was PATHETIC and quality was mediocre... while the plants I topped were huge bushes that yielded lots of tasty buds. With that, I will say... topping too much can cause the bush to only create popcorn buds.