I'm in zone 5 and I have 5 large clumps of Chinese Silver Grass. I bind them up with a little twine and leave them up all winter. They look nice against the snow. Altho, I have no snow at the moment. It was 60F here yesterday Normal is 30F. In the Spring I chop them down to the ground with the hedge trimmer and machete. Run my lawnmower over them with the bag on and dump it all in the pile. Once I add a little green grass to the pile it all breaks down fairly fast. As with most additions to my pile, the smaller the size the faster it composts,

"they may not look very good" is an understatement. The blade of foliage will have squared-off and probably browned edges at the end, and will look terrible. Depending upon the type of grass, you may also delay, diminish or completely abort blooming. The only solution is to move them.

It's a yuck get rid of

Weed B Gon...well, I'd test that theory before using it, although if the previous owner got away with it, it should be OK. There are plenty of species of grass you can't use it on. Still, I'm not willing to give it a green light without knowing the exact species of ornamental and seeing that species on the label as being OK and wouldn't recommend using it without testing unless you have that assurance. RoundUp will kill any green plant it touches that hasn't had a certain gene sequence inserted. Yours are not immune. Don't use it. With my Zebra grass, a lot of manual effort is required. It's often best to inspect weekly and take care of problems as they develop. That little tree is easier to remove as a tiny seedling rather than wait until it's a sapling. Annoying, sure. But that's true of most problems, I guess. Mulching will certainly help, as will application of Preen early in the season next year (although take a look at the weeds you actually get and match the correct pre-emergent to the correct weeds. I have been...well, less than impressed with Preen, let's just say, due to my weed profile). Reapply said pre-emergent when the shield runs out, which will be dependent on the pre-m and the dose used (my Prodiamine lasts 9 months, but that's the dose I use--and it's the maximum for the year). Like any other summer-growing grass, these also benefit from a moderate feeding on-schedule. You can look up care online, or just ask and we'll outline the care and feeding strategy for you. This is already getting kind of long.