With proper water params, GSP spreads so quickly you can just as well place a small rock right up against the fringe of your colony and within a month or two it will start to attach to the rock. Unless you are in a bind to have to frag, that of course is the safest way, no need to risk harming the coral. GSP is the saltwater equivalent to weeds! Every time I go to my LFS I always ask him for little pieces of LR that break off in his tanks, he just gives them to me, and I trade my GSP frags back in for other stuff. I have fragged my GSP this way at least 6 times now.