Chinese Silvergrass

 

Ecological Considerations:

Miscanthus sinensis is a highly variable robust perennial grass that grows commonly in large clumps and can reach 12 ft. high. The clumps or bunches can grow as wide as 3 feet. Chinese Silvergrass propagates primarily by seed. Its branches are flexible and spread or droop. The leaves are elongate and can grow 3 ft.long and as wide as an inch. The leaves have a silver white midrib. The tips of the leaves are sharp and recurving.

Mature plants have large, feathery flowers in September and October. Chinese Silvergrass grows in open disturbed areas, along roadsides, on the edges of woodlands, in vacant lots, and on steep embankments.

Chinese Silvergrass prefers light, well-drained soils that are low in nutrients. It grows well in full sun.

Problems Posed by this Plant:

Chinese Silvergrass can form large, dense clumps that displace native species.

Native Species Affected by this Plant:

Factors Affording a Competitive Advantage to this Plant:

Chinese Silvergrass self-seeds readily and also propagates aggressively, vegetatively via rhizomes.

Propagation Mechanisms and Related Issues Affecting Efforts to Remove and/or Eliminate this Plant from Taylor Point:

Miscanthus sinensis sets a significant amount of airborne seed. Seed is the primary method of disbursement. Chinese Silvergrass also reproduces effectively vegetatively via rhizomes. Efforts to remove plants are often confounded by the persistence of the rhizomes and their capacity to regenerate once disturbed.

Documented Best Removal Practices and Options/ Pros and Cons of Various Options: 

More than 50 ornamental forms of Miscanthus sinensis are sold in the US nursery trade. Ornamental plantings should be watched carefully for self-seeding into nearby woodlands, or natural areas. In the fall, when flowers are conspicuous, usually October, is a good time to look for self-seeded plants. It is advisable to hand pull or dig out new plants, taking care to dig out the entire root system, and to remove flowers to prevent further self-seeding. Removing seedheads as they appear will reduce the seedbank and control the spread of plants.

For more extensive colonies, repeated mowing, as short as possible throughout the growing season can eliminate Miscanthus sinensis usually in 2 seasons. Mowing is best done before the formation of flower head, which occurs in September through October.  In areas bearing a strong seed bank, several years of mowing may be necessary. Areas should be mowed at least twice per year or monthly during the growing season. However, cutting the plants back in late winter or when they are dormant will not reduce or eliminate them and can actually enhance growth if the cuttings are removed, similar to haying.

If mowing is not feasible, remove seed-heads to reduce the likelihood of spread to new areas.

Burning is known to increase the growth and seed set of Chinese Silvergrass. Burning can only be effective against this invasive grass if the burning is followed by chemical treatment. Burning in late winter or early spring will remove all of the previous years growth. Plants will regrow with increased vigor, and, if allowed to flower, the seed set can actually be enhanced after burning. Burning, however, can clean an area so that all foliage will be green and actively growing for effective and efficient chemical control.

If burning followed by chemical control is pursued, managers should, in late winter or early spring, before new growth starts, burn the previous year’s growth entirely, back to the ground. This removal ensures vigorous new growth and the lack of any dead leaves or culms, thus establishing ideal conditions for chemical control.

When new growth is about 12” tall, in mid spring or early summer, spray all green tissue with glyphosate. Allow plant to die, and when completely brown, cut the dead foliage back to the ground. Repeat the process the following year, if necessary.

Chemical spraying of the cut surfaces after cutting plants back (often recommended for controlling woody plants) is NOT an effective way to control Miscanthus. An adequate amount of actively growing green foliage should be present for good chemical control.