I apologize for the less-than-stellar photo. It was windy, and all those dangly seed heads were dancing merrily with every gust. River Oats are a lovely native grass suitable for moist, shady spots in your piedmont garden. Native to the Carolinas and Georgia, it occurs naturally on the banks of rivers and streams, bottomland forests, and other wet spots, especially in fertile soils. It has a number of other common names, including Inland Sea Oats, Indian Wood Oats, Wild Oats, Flathead Oats, and Upland Oats.
It looks a lot like a coastal grass famous for stabilizing our sand dunes: Sea Oats (Uniola paniculata). If you’ve visited our southeastern US sand dunes, you’ve likely been told not to pick the Sea Oats, because their roots help prevent sand dunes from moving. When you pick the pretty seed heads for arrangements, you reduce the species’ chances for propagating and thereby stabilizing more dunes.
River Oats have no such restrictions. And they are lovely long-lasting additions to dried flower arrangements. They are one of the few native shade-tolerant grasses that grow well in the southeastern piedmont, and they’re also very easy to establish — as long as you give them decent soil and a bit of moisture.
River Oats forms clumps. Flower stalks range between 2-4 feet. Mine stay about 2.5 feet tall. I grow mine at the bottom of my north slope garden that is now enclosed by a deer fence. But even before that fence was in place, the deer never even nibbled on this grass. As is true of just about all our native grasses, the deer ignore them.
These grasses would be ideal in a rain garden — a low spot in your yard where water collects after rains. That extra bit of moisture is all they need — as long as they’re also in the shade. Because they’re clumpers, they mix well with other moisture-loving native flowers, such as Swamp Milkweed. River Oats also work as part of potted plant arrangements — as long as they are sited on a shady porch and adequately watered.
If you don’t cut the mature seed stalks for flower arrangements, they will morph from summer ivory to an autumnal soft brown, eventually weathering to a silvery gray by late winter. By then, most of the seeds will have been devoured by small mammals and grain-loving birds. The leaves are a food source for several species of native skipper butterflies.
I planted three pots of River Oats around a large boulder at the bottom of my hill over 20 years ago. Very gradually, the clumps have grown, and just a few seeds missed by animals have created new plants. The boulder now has a soft and lovely green skirt of River Oats, topped much of the year by dancing dangling seed heads. I highly recommend this native grass to all piedmont gardeners, especially to those with shady damp spots in their yards.
And while I’m writing of wet spots, I must share this recent photo of one of the many dragonflies that patrol the numerous wet areas in my yard. This one was lingering around the front water feature. We think we’ve even identified it, but if I’ve got it wrong, I hope an Odonata expert will set me right.