Cogongrass (Imperata cylindrica) is one of the world’s ten worst weeds and has already invaded 153 billion acres worldwide. Cogongrass is becoming established in Florida, Georgia, Alabama, Mississippi, and Louisiana and is now found in South Carolina. In Florida alone, it has infested one million acres, where it has displaced many native species of plants. Cogongrass will invade pastures, where it reduces the forage quality because its leaves are unpalatable to livestock. It can quickly displace other vegetation in forests and fields, including native plants that birds and small animals need for shelter and forage.
The Means of Spread
This weed spreads not only by an aggressive root system but also by fluffy white seed heads that produce an abundance of wind-blown seed in the early summer. It is very tolerant of soil type and wide variations in soil fertility, moisture, and light conditions.
Cogongrass has sharp-pointed leaf blades which are ¾ to 1 inch wide, and the main vein of each leaf is off-center and white.
For more information on cogongrass identification, please see: www.cogongrass.org/identification
Japanese bloodgrass (Imperata cylindrica ‘Red Baron’) is a 2-foot tall perennial grass with red and lime-green leaves. The problem is that Japanese bloodgrass (‘Red Baron’ bloodgrass) is a variety of cogongrass, and this red-leafed ornamental grass can revert to the extremely aggressive, 4 to 5 foot-tall, green form. Sales of this popular ornamental grass have been halted in South Carolina, but plants have been brought in from other states. Although this grass might make a nice colorful addition to the perennial garden, its highly aggressive nature warrants us to think twice about planting it.
For gardeners who would like to have a red-leafed ornamental grass in their perennial beds, there are other choices. There are several cultivars of our native switchgrass (Panicum virgatum) that have red foliage, which is especially prominent in mid-summer through fall. The species and the cultivars of switchgrass are non-invasive plants and form clumps that slowly spread by creeping rhizomes. They grow best in full sun gardens and are adapted to a wide range of soil conditions. These switchgrasses grow well in USDA zones 4 to 9.
- ‘Blood Brothers’: The green-blue foliage develops blood-red tones by mid-summer. This selection grows to 4 to 5 feet tall and 2½ to 3 feet wide.
- Prairie Winds™ (‘Cheyenne Sky’ PPAF): This cultivar grows to 30 to 36 inches tall and 14 to 18 inches wide. The foliage turns wine red in early summer.
- ‘Hot Rod’ (PPAF): This selection grows to 36 to 40 inches tall and has early red color development.
- ‘Prairie Fire’: This 4 to 5-foot tall selection spreads to 3 feet wide, and its blue-green leaves develop wine red tips in mid-summer.
- ‘Red October’ is a native big bluestem grass that has narrow, deep green leaves with red streaks. In the fall, the red hue changes to burgundy, and after the first frost, the foliage turns candy-apple red. When in bloom, it reaches a height of 5 to 6 feet. USDA Zones: 3 to 9.
- ‘Rotstrahlbusch’: This older cultivar grows 4 to 5 feet tall and 2 to 3 feet wide. The foliage changes to burgundy red by autumn.
- Ruby Ribbons™ (‘RR1’ PP#17944): This is a newer selection of switchgrass that grows to 3 to 4 feet tall and 2 to 2½ feet wide. The foliage matures by mid-summer to a purple-red.
- ‘Samurai’: This cultivar grows to 4 to 5 feet tall and 3 feet wide. The blue-green leaves develop red tones by mid-summer and intensify by autumn.
- ‘Shenandoah’: This is one of the earlier cultivars and grows 2 to 3 feet tall and 2 feet wide. The foliage becomes a dazzling red in fall.
Report Any Sightings
Clemson University’s Department of Plant Industry is a member of a task force, which includes the SC Forestry Commission and the US Forest Service, with the goal of preventing the spread of cogongrass within South Carolina. If you have Japanese bloodgrass or have seen cogongrass in your area, contact the Clemson Department of Plant Industry at 864-646-2140. Any sighting will be investigated.