Some strains also don't like topping. Especially slower growing strains. I myself usually don't top, even fast growing strains like Mr Nice Super Silver Haze, but Train my plants by bending. I hate giving up the main terminal node. While it may be true in the long run topping ect, may have advantages, but topping a plant also sets it back, and from what Ive found slows the veg/harvest cycle because I have to veg 2 weeks for the 2 growing tips to catch up to where the original was, and if you consider the untopped plant would also continue to grow, and still produce more lateral branching, its not worth it to me.
If I as going to top, Id probably do it at the 5th-6th node.
Heres what Ive used before with the best results. I got this from High Times 20+, and is a good method.
When first true leaves are out, cut 1 off, then when second set comes out, cut the Opposite side leaf off 2nd set, and alternate until the 5th-6th node, and then top.
Other than the defoliation that goes on with this method, I'm also not big on defoliation. But I also use 1000w HID for veg, and always have, and get good penetration even on the leafiest plants. Bending the crap out of them, and making all the secondary branching grow vertically exposes them better. No Comparison, and am a firm believer for making my plants grow Horizontally vs Vertically. This alone opens them up I train all the side branching along with the growing tip. But after a certain point, the plant side branching wont require any more mucking with.
Some strains are also very stiff, and you have to start training them like this from very early on, or they'll be to stiff to bend, and break like a pencil.
