Here's some info from a recent thread (a lot of non-info in there too http://boards.cannabis.com/plant-pro...3some-cup.html

Quote Originally Posted by bigtopsfinn
They strongest plant of the 3 will win this battle, and kill the other 2 eventually. You need to separate them immediately. Best way would be to take them out of the cup, and use lightly running water to wash off the soil so you can untangle the roots and replant into separate cups. Hopefully they aren't too tangled yet and you won't have to damage the roots too much.
I was semi-successful doing this with my wife's chili plants... but I think ImageReaper's method sounds better :thumbsup:

Quote Originally Posted by the image reaper
in my bagseed days, I purposely started 3 seeds in every pot, and when they were a couple inches tall, I'd take scissors, and snip off the less vibrant of the 3 ... I'd then grow out the remaining seedling, and never had any problems, whatsoever ... I did it that way, because I didn't know it was better for them to be in separate pots ... ignorance is bliss ... as to splitting them up, (instead of trying to untangle the roots), I have caused less root damage, by simply snipping the root balls apart with clean scissors :wtf: ... if one of your seedlings is significantly healthier than the others, it's an easy decision ... :jointsmile: