'Gracillimus' usually comes alive fairly early. I'm a couple of zones warmer, but my in-ground 'Gracillimus' are nearly a foot tall already, and those in containers are at least 6".

Zone 5 is at the bottom end of this grass's hardiness range. I used to garden in NE Ohio (Geauga County) and lost more than a few Miscanthus to nasty winters..even mature ones.

There should be no problem with turf grass overwhelming healthy Miscanthus. You should, however, give the OGs a bed of their own, so they have no competition from the lawn grass.

Did you cut the OGs back recently?

I cut them back just about a month ago. At the beginning of April.

That's the right time.

All you can do is cross your fingers and wait. If you had a typical NE Ohio (snow belt) winter, with lots of snow, they should be ok. I lost mine during years where the cold arrived before the snow.