I bought 100 rhizomes of giant miscanthus and planted them on my perimeter. They are definitely miscanthus and the root ball gets bigger every year, but it doesn't reach and run. They are truly lovely, 10ft tall, woody finger thick stakes, they rustle on the wind, and stay visually interesting once dry throughout the winter. They are able to be bushhogged or scythed and tolerate drought. Not sure you could ever get them out once in though.
