20 May 2005 Page 1 of 3 

Plant Conservation Alliance®s Alien Plant Working Group 

Xeeds HoneXild: Alien Plant Invaders of Natural Areas 

http://www.nps.gov/plants/alien/

FACT SHEET: COGON GRASS

Cogon Grass 

Imperata cylindrica (L.) Palisot 

Grass family (Poaceae) 

NATIVE RANGE 

Southeast Asia, Philippines, China, and Japan 

DESCRIPTION 

Cogon grass is a perennial, rhizomatous grass that grows from 2 to over 4 feet in 

height. The leaves are about an inch wide, have a prominent white midrib, and 

end in a sharp point. Leaf margins are finely toothed and are embedded with 

silica crystals. The upper surface of the leaf blade is hairy near the base; the 

undersurface is usually hairless. The flowers are arranged in a silvery, 

cylindrical, branching structure, or panicle, about 3-11 inches long and 11⁄2 inches 

wide. 

ECOLOGICAL THREAT 

Cogon grass can invade and overtake disturbed ecosystems, forming a dense 

mat of thatch and leaves that makes it nearly impossible for other plants to 

coexist. Large infestations of cogon grass can alter the normal fire regime of a 

fire-driven ecosystem by causing more frequent and intense fires that injure or 

destroy native plants. Cogon grass displaces a large variety of native plant 

species used by native animals (e.g., insects, mammals, and birds) as forage, 

host plants and shelter. Some ground-nesting species have also been known to 

be displaced due to the dense cover that cogon grass creates. 

DISTRIBUTION IN THE UNITED STATES 

Cogon grass is distributed throughout the south and southeastern United 

States as far west as eastern Texas. There have been reports of cogon grass 

surviving as far north as Virginia, West Virginia and Maryland. 

HABITAT IN THE UNITED STATES 

Cogon grass is a hardy species, tolerant of shade, high salinity and drought. It 

can be found in virtually any ecosystem, especially those experiencing 

disturbance. Cogon grass has been found growing on sand dunes in the 

southeast, along roadsides, forests, open fields, and up to the edge of standing 

water. 

BACKGROUND 

Cogon grass was introduced to the United States both accidentally and intentionally. 

Cogon grass was first introduced to the U.S. at Mobile, Alabama, via shipping crates that 

contained cogon grass as a packing material. It was also brought in and distributed by 

the U.S.D.A. for use as a forage grass and for soil erosion control. Cogon grass is also 

sold by the nursery trade as an ornamental grass, valued for its attractive foliage and 

hardiness. 

BIOLOGY & SPREAD 

Cogon grass reproduces both vegetatively and from seed. A single plant can produce 

several thousand very small seeds that may be carried great distances by the wind. 

Vegetative spread of cogon grass is aided by its tough and massive rhizomes that may 

remain dormant for extended periods of time before sprouting. Rhizomes of cogon grass may be transported to new sites 

in contaminated fill dirt or by equipment used in infested areas. 
20 May 2005 Page 2 of 3 

Plant Conservation Alliance®s Alien Plant Working Group 

Xeeds HoneXild: Alien Plant Invaders of Natural Areas 

http://www.nps.gov/plants/alien/

MANAGEMENT OPTIONS 

An integrated approach to cogon grass management, including chemical, 

mechanical and cultural methods, is necessary to achieve successful, long 

lasting control. Effective management of cogon grass has been achieved by 

the following combined mechanical-chemical protocol. First, the infested 

area is mowed in late spring to remove last year’s growth and the 

accumulated thatch layer. About six to eight weeks later, when about eighty 

percent of the cogon grass has resprouted to a height of 6-12 inches, the site 

needs to be disced as deeply as possible. Discing may not be possible in all 

areas, due to the sensitive nature of some ecosystems. When adequate 

regrowth of the cogon grass has occurred, systemic herbicides (chemicals 

are carried through the plant tissues to the roots) are applied. 

The best time to apply herbicides is in the early fall before first frost. A 2% solution of glyphosate (e.g., Roundup®) is 

recommended in areas that will be immediately revegetated, because glyphosate has no residual soil activity. In areas 

where immediate revegetation is not planned, and non-target plant damage is not a concern, application of a 1-1.5% 

solution of imazapyr (e.g., Arsenal®) may be considered. IMPORTANT: Because imazapyr is highly active in soil, it has a 

high potential for leaching into groundwater, so should only be used when groundwater impacts can be eliminated or 

minimized. Additionally, nearby trees or other plants may be damaged by improper application of this herbicide. 

Revegetation may be necessary following herbicide treatment, to prevent soil erosion and to help reduce reinfestation by 

cogon grass. For roadside areas, revegetation with bahia grass and bermuda grass have been used successfully for 

these purposes. In natural areas, the choice of which species to use for revegetation becomes more difficult. For some 

areas, assisting the process of natural revegetation succession may be the best choice. Once decisions are made 

regarding the ultimate goal of the restoration project, revegetation plans should be made accordingly. Regardless of the 

goal, the area should be revegetated quickly to allow a stable plant community to be established. Lastly, it is important to 

exercise diligence, as it will be necessary to scout areas that have been treated for cogon grass and spot treat new plants 

with herbicides. 

It may not be possible to use all of the methods prescribed above in every situation, but most effective control will be 

gained by using as many of the steps outlined above as possible. In areas where burning, mowing, or discing, are not 

possible, spot treatment with herbicides will help to control cogon grass. Revisit treated areas frequently and retreat with 

herbicides as necessary. The best time to begin a control program is late spring to mid-summer when cogon grass is 

experiencing peak growth. Some control measures, such as mowing and spot spraying with herbicides, can be 

implemented year round. 

Fire 

Burning has also been used successfully in controlling cogon grass. As with mowing, burning stimulates the growth and 

spread of cogon grass, making followup control a necessity. If you are interested in attempting this technique, contact 

management specialists listed below for more specific information. Also, be sure to obtain all required permits before 

attempting a burn even on small infestations. 

USE PESTICIDES WISELY: Always read the entire pesticide label carefully, follow all mixing and application instructions and wear all 

recommended personal protective gear and clothing. Contact your state department of agriculture for any additional pesticide use 

requirements, restrictions or recommendations. 

NOTICE: mention of pesticide products on this page does not constitute endorsement of any material.

CONTACTS 

For more information on the management of cogon grass, please contact: 

• Donn G. Shilling, Ph.D., University of Florida, Weed Science / Agronomy, Center Director and Professor, West 

Florida Research and Education Center, (850) 484-4482 or 983-2632, dgs at gnv.ifas.ufl.edu 

• Eric R. R. L. Johnson, University of Florida, Graduate Research Assistant, Weed Science / Agronomy, (352) 392-

7512, Voice mail (352) 392-6598 ext 310, errlj at nersp.nerdc.ufl.edu 
20 May 2005 Page 3 of 3 

Plant Conservation Alliance®s Alien Plant Working Group 

Xeeds HoneXild: Alien Plant Invaders of Natural Areas 

http://www.nps.gov/plants/alien/

SUGGESTED ALTERNATIVE PLANTS 

A number of native plants should be considered for replanting areas that were infested with cogon grass. Along roadsides, 

bahia grass (Paspalum notatum) is a possible choice. Each scenario will require a different approach to return an area 

previously infested with cogon grass to a healthy ecosystem. Specialists in cogon grass management should be 

contacted for assistance. 

OTHER LINKS 

• http://www.invasive.org/search/action.cfm?q=Imperata%20cylindrica

AUTHOR 

Eric R. R. L. Johnson, University of Florida, Weed Science, Gainesville, FL 

Donn G. Shilling, Ph.D., University of Florida, Weed Science, Milton, FL 

EDITOR

Jil M. Swearingen, National Park Service, Washington, DC 

PHOTOGRAPHS 

Jeffrey Lotz and Luanne Marsh with the Florida Dept. of Agriculture, Division of Plant Industry 

REFERENCES 

Gaffney, J. F. 1996. Ecophysiological and technological factors influencing the management of cogon grass (Imperata 

cylindrica). Dissertation. Agronomy Department, University of Florida, Gainesville, Florida. 

Johnson, E. R. R. L. and D. G. Shilling. 1998. Hernando County Final Report. Agronomy Department, University of 

Florida, Gainesville, Florida. 

Lippincott, C. L. 1997. Ecological consequences of Imperata cylindrica (cogon grass): Invasion in Florida Sandhill. 

Dissertation. Botany Department, University of Florida, Gainesville, Florida. 

Swearingen, J. 2009. WeedUS Database of Plants Invading Natural Areas in the United States: Cogon Grass (Imperata 

cylindrica). http://www.invasive.org/weedus/subject.html?sub=2433. 

USDA, NRCS. 2009. The PLANTS Database (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 

70874-4490 USA.