If you can cut it back without cutting the new growth, it's not too late. In our area, the new growth is just beginning to appear, so I'm going to cut mine back to the top of the new shoots.

I've cut miscanthus almost to the ground in the middle of summer with absolutely no problem. It's a "grass" - it keeps on growing, just like your lawn. Treat it as such and you'll have no problem whatsoever.

Nelson