Ask Mr. Smarty Plants

We are surprised to find someone wanting to get rid of Chasmanthium latifolium (Inland sea oats). In Texas, many gardeners love it, because it is one of the few grasses that really do well in shade, it looks good most seasons, and will virtually make a hedge with it's graceful stems and "oats" hanging over. However, everyone has their preferences and we will see what we can do to help you.

From Wayside Garden, we found this article Three Seasons of Showy Color for the Shade; they don't consider it invasive but several of the responders in Dave's Garden do. This Floridata site, Chasmanthium latifolium, conceded that it could be invasive if you had it in moist soil and sun, so that's at least a clue.

We found no one saying "This is a pest, and this is how to get rid of it," so we will have to do it. First, don't let it seed; in fact, keep it cut down very low. This can eventually starve it out, but it's a little slow. The roots are apparently fairly easy to transplant, so we're assuming they are also easy to dig out. If you have it growing in a garden situation, that is going to make it harder, because you may have to keep the soil moist for the garden plants, and don't want to disturb the other plant roots to dig up the grass roots. It can spread both by seeds and roots, you'll have to address it on both fronts. Since it is a grass, a member of the Poaceae family, you can purchase a weed killer for monocots, only; that is, grasses. When a plant has a good root system like this one does, it's difficult to get the herbicide to the roots. You might try cutting it down as much as you can, which eliminates seed, and then painting the stalks left in the ground with the herbicide and a small disposable paint brush. Be careful, though, your lawn is probably a grass, too, so we don't recommend spraying. Dig out as many of the roots as you can, and dispose of them where they won't regrow. You'll have to keep watching for it and grubbing it out as it comes up in the Spring. 

From our Native Plant Image Gallery:

Chasmanthium latifolium

Chasmanthium latifolium

Chasmanthium latifolium

Chasmanthium latifolium