Will feature grass spread and take over a garden or yard?
I have personal experience with Karl Foerster Feather Reed grass, Calamagrostis. I did not cut it down before winter so it had ample time to drop seed. The original clump slowly increases in size but I had a dozen seedlings or so every year. They were hard to pull by hand and I ended up cutting off the seed heads as they formed. So it is primarily a clump forming grass and does not spread via rhizomes. Unlike Miscanthus, it is not listed as invasive at this time. In a neglected area, it will self-sow.