Cerastium tomentosum is "Snow in Summer" I didn't realize it was a perennial. You can spray a herbicide which selectively kills monocots (grasses) and will not impact dicots (broadleaf plants).

A quick google search of "monocot herbicide" comes up with "Sethoxydim" which there are a number of generics for.

http://www.domyownpestcontrol.com/sethoxydim-c-114_470.html

i would never have the guts to do that ...

dig it up ... edge the bed ... separate the two ... replant ...

and next time.. stay on top of it ... its much easier to remove a few new pieces of grass in spring.. than redig the whole bunch ... eh ... been there.. done that ...

ken

Thanks to both of you. I think I will do as Ken said and dig it out. I may start tonight because tomorrow is rain and that will be good if I have to plant the snow in summer back. Shouldn't take too long. I thought I would probably have to do that. I love the snow in summer so will do what it takes . The lawn is next to the bed so some just seems to grow in the edge of the flower bed. Or I didn't get it all out when I planted the snow in summer last fall. Yes Ken you are so right I need to be better in tune to this and get it out the minute I see it. Thanks again to both of you for your help.