The beautiful Asian ornamental grass genus Miscanthus, or Silvergrass, contains several species widely planted in gardens throughout the eastern U.S. One of the most frequently used is Miscanthus sinensis, Chinese silvergrass or Eulalia. Over 50 cultivated varieties, or cultivars, have been introduced to American horticulture since 1980, primarily by German and American growers. Some of these cultivars tend to hybridize naturally. Careful selection has produced a range of bloom times beginning in late summer and stretching well into the fall. As we plant more of these graceful and elegant plants, we also notice more of them occurring along roadsides and in locations where they were not planted purposefully. How invasive is Miscanthus? This question, and the light wind-blown blossoms and seed heads now on display, led the Maryland Invasive Species Council to choose Miscanthus sinensis as October’s Invader of the Month.

Miscanthus sinensis is a perennial clumping grass, the clumps expanding out from the center of the plant over time by way of short, thick rhizomes. It can easily reach over six feet in height. The leaves are mostly basal and hairless, although there are often hairs present at the throat of the sheath, where the leaf spreads out to become the blade. Leaf blades are usually 3/8” to ¾” wide, and are erect with gracefully drooping tips. Their whitish midveins are obvious on the undersides of the leaves. Bloom clusters or panicles, which in the Mid-Atlantic appear from September into October, can be dense or open, are usually heavily branched, with colors ranging from pinkish to silvery white. The seed heads and leaves both dry to a golden brown color in the winter. Miscanthus sinensis is native to lowland and mountain slopes in Japan, Korea and China. It grows best in rich, well-drained soil in full sun, but is fairly drought-tolerant and can easily withstand Maryland winters.

In Maryland, Miscanthus can be found along roadsides and disturbed areas, spreading beyond the bounds of tended gardens. In most cases reported, these escapees are the straight species or “wild type,” Miscanthus sinensis. Although Miscanthus does spread vegetatively, its ability to colonize new areas is dependent on wind-blown seed. Species and cultivars that produce less viable seed are thus less likely to become invasive. In research conducted in Minnesota and funded in part by the Perennial Plant Association of America, Hockenberry-Meyer et al. tested seed viability in the straight species and 38 different cultivars from USDA hardiness zones 5, 6 (most of Western Maryland) and 7 (Maryland’s lower Piedmont and coastal plain). They found that the following cultivars set less than 18% viable seed, and so were good candidates for non-invasive garden plants.

• ‘Autumn Light’
• ‘Dixieland’
• ‘Kirk Alexander’
• ‘Little Kitten’
• ‘Morning Light’
• ‘Rigoletto’
• ‘Silberfeil’
• ‘Strictus’
• ‘Variegatus’
• ‘Yaka Jima’

The researchers’ recommendations for growing, selling and buying Miscanthus cultivars appear on their website: http://horticulture.cfans.umn.edu/miscanthus/recommendations.htm. For the gardening public, they suggest buying only named Miscanthus cultivars, not the species, and to label and watch any plants in your garden carefully for self-seeding. To avoid any potential problem, consider using a native warm season grass like Switchgrass, Panicum virgatum, or Indian grass, Sorghastrum nutans.

The non-invasive members of the genus Miscanthus are not only beautiful, they are workhorses. A natural hybrid of M. sinensis and another species, M. sacchariflorus, called M. x giganteus is being grown extensively in Europe as a biomass fuel and for fiber. U.S. scientists are also working with this pollen-sterile hybrid, which can grow to 12 feet tall. The Minnesota team reported on their website that, as of three years ago, it had not set viable seed at any location throughout the world.

For more information about other Invasive Species of Concern, visit www.mdinvasivesp.org or call the Maryland Department of Agriculture at 410-841-5920.

For more information on the Internet:

Grass Manual on the Web, (scroll down to Miscanthus)

USDA NRCS Plants Profile

The Nature Conservancy

University of Minnesota