I have to frag them frequently otherwise I end up with large dead sections. They either grow into my horn coral, into each other or up to the glass. This is actually the second time I've grown them to the size they are now. I had to sell off my last colonies (which barely fit into a salt bucket) so that I could start over again.
Here is a picture of my last colonies just before I sold them and started over from frags that I kept.
