In zone 9, I would expect Miscanthus to self-sow moderately. It does so in my zone. Growing in a container would not prevent this...only deadheading will.

Fine Gardening recently published results of some research on viability of Miscanthus seeds. They concluded that only Giganteus is truly sterile. Good Thing! In my climate they are all functionally sterile.

I think the invasiveness of Miscanthus sinensis is somewhat overstated. First, its seed fertility is not self-compatable. That means you need to cross 2 different cultivars of miscanthus to get fertile seed, just like you would need two different types of apples to get fruit. So growing a single variety is unlikely to result in any self seeding.

The issue arises when there are multiple types of miscanthus being planted or when neighbors may be growing other varieties. Here in my climate, we have mild enough summers that we are lucky to get miscanthus to set a good plumes or seedheads before the cold weather sets in. Seeds simply do not ripen in time to be an issue with this OG.

"its seed fertility is not self-compatable. That means you need to cross 2 different cultivars of miscanthus to get fertile seed...[]...when neighbors may be growing other varieties."

This is probably the issue. I only had _one_ Miscanthus, but it seeded just enough I decided last year I'd had enough. It wasn't insurmontably weedy, but it was annoying. Although, the bigger issue was I'd always intended it to be temporary, until some BLEs were big enough to be screens.

HaHa....interesting.....I'm also Zone 9 / Sunset zone 17 and bought a few NOID miscanthus from WalMart two years ago.....same batch? Good info, thank you....I'd wondered the same thing.