River oats is not a grass for the feint-of-heart. It can form very large patches. But it is a work-horse for large and difficult weedy areas where a native cover is desired. It naturally forms patchy mixed stands along river-banks and flood-plains often mixing in with obedient plant and various coreopsis and sunflower species. Grows 2-4' tall. Not fussy as to soil type though leaner soil will help keep it in check. Prefers a shade to part shade situation. Flowers/seed-heads appear midsummer from July to October. Dried they remain an interesting garden component well into the winter. Zone 3-8. WV. ecotype.