Imperata cylindrica
Federal Noxious Weed: Do Not Plant
Common Name: cogon grass 
Type: Ornamental grass
Family: Poaceae
Native Range: Japan
Zone: 5 to 9
Height: 2.00 to 4.00 feet
Spread: 2.00 to 4.00 feet
Bloom Time: Rarely flowers
Sun: Full sun to part shade
Water: Dry to medium
Maintenance: Medium
Suggested Use: Naturalize
Tolerate: Drought, Black Walnut, Air Pollution
This plant is listed as a noxious weed under the Federal Noxious Weed Act of 1974 (7 U.S.C. 2802 ©) and as such may be moved into or through the United States only under permit from the USDA Plant Protection and Quarantine Program, and under conditions that would not involve a danger of dissemination.

Culture

Easily grown in dry to moist, well-drained soils in full sun to part shade. In warm winter areas, it naturalizes aggressively by both rhizomes and self-seeding to form dense monocultures which displace native species. It is tolerant of shade, poor soils, and drought. It tends to be less aggressive in the cooler conditions of USDA Zones 5-6.

Noteworthy Characteristics

Imperata cylindrica, commonly known as cogongrass, is now considered to be one of the ten worst weeds in the world. It is native to Korea, Japan, China, India, and tropical eastern Africa. It was introduced into the southeastern U.S. in the early 1900s, unintentionally in the form of packing materials contained in shipping cartons imported into the U.S. and intentionally as a forage grass and/or erosion control plant. This grass is now listed as a Federal Noxious Weed under the Plant Protection Act which means it may not be imported or transported between States without first obtaining a federal permit. It has also been declared a noxious weed by a number of States including Florida, Alabama, Mississippi, North Carolina, South Carolina, Georgia and Hawaii.

This is an opportunistic, rapid-growing perennial grass that spreads invasively in warm winter locations, particularly evident in the southeastern U.S. from South Carolina and Florida to Texas. It is typically found in a number of different sites including roadsides, pastures, mined areas, fields, sand dunes, utility right-of-ways and dry scrubs. It grows in spreading clumps to 2-4’ tall. Yellowish green leaves (to 30” long and to 3/4” wide) feature finely serrated edges, off-center light green to white midribs, and sharp tips. Flowers in cylindrical spikes to 16” long bloom in early spring (March-May), albeit infrequently, in the northern parts of its growing range, but can flower year round in semi-tropical to tropical areas.

Some authorities currently list this grass as being present in five or more varieties, including var. major (the highly invasive variety described herein which is found in the wild in east/southeast Asia and the southeastern U.S.) and var. rubra (non-invasive ornamental red leaved cultivars still sold by nurseries in some states under the common name of Japanese bloodgrass).

Genus name honors Ferrante Imperato (1550-1625) an apothecary (pharmacist) of Naples.

Specific epithet means long and round, cylindrical.

Problems

No known serious insect or disease problems. Green-leaved species plants are highly invasive.

Garden Uses

Under Federal law, it is illegal to transport cogongrass into or within the United States without first obtaining a permit. Several states have laws forbidding its sale or growth.