My Foam Flowers have only been in the ground 2 years and already have spread to form nice big clumps. I would like to divide some of them, but am unsure how to go about it. How easy would it be to divide off the runners and how to do it? Cut the clumps with a knife or is there another (safer) way so not to damage the roots? Are they easy to divide like Hostas?

Thanks for your help.