+1 to what was said above, but I've also found that if you can actually get a piece of rock or substate on the bottom of the zoas to glue to, you're going to have a much better survival rate. A set of sidecutters works great to cut a plug up into multiple pieces, and then glue the plug piece rather than the zoas themselves. If you're taking from a large colony, use a chizel and remove some of the rock with the zoas that you are cutting.