Invasive Cogongrass Set to Bloom In Coming Weeks

by | May 22, 2023

As the weather across North Carolina continues to warm up, an invasive species will soon show its true colors.

A weed called cogongrass will develop its seed head later this month or in early June, revealing its presence and offering the North Carolina Department of Agriculture & Consumer Services’ Plant Industry Division a chance to work toward eradicating it.

North Carolinians in Pender and Sampson counties should be on the lookout for cogongrass’ distinctive puffy white seed head atop a tall blade of grass.

Cogongrass seed heads in bloom. Photo: NC State Extension

“The grass starts to shoot up in mid-to-late May and if you have an early spring like we did this year, then maybe by late May you’ll start to see some blooms,” said NCDA&CS Weed Specialist Jared Driscoll. “June is the standard time in North Carolina to see these cylindrical seed heads. That’s the number one way to identify cogongrass.”

Besides the dandelion-like seed head, there are a couple of other ways to identify cogongrass. Cogongrass blades are about an inch wide and grow up to six feet tall. The plant grows in tight, circular clumps and is very difficult to pull up by hand.

Cogongrass is native to southeast Asia and has been in North Carolina since about 2012. Its footprint in North Carolina is shrinking, but there is still work to be done before achieving eradication.

In addition to throwing the ecosystem out of balance by displacing native plants and insects, one of the primary dangers of cogongrass is that it burns at a higher temperature than native vegetation, leading to more dangerous fires than crews would otherwise have to deal with.

“Cogongrass is allelopathic, which is a fancy plant science way of saying it produces its own chemicals that inhibit the growth of other plants around it,” Driscoll said. “Already, cogongrass grows very dense and nothing will grow in the middle of a cogongrass infestation. If you’re a forester and you’re doing a prescribed burn and there’s cogongrass around, it gets complicated.”

North Carolinians should be on the lookout for cogongrass in the wild, but they should also be aware of variations on the plant being illegally sold in nurseries. If consumers see a plant labeled as either Japanese Bloodgrass or Red Baron, they should report that to the Plant Industry Division as those plants are variations of cogongrass that can revert back in the wild.

The Red Baron form of cogongrass. Photo: NC State Extension

Community members should report potential cogongrass sightings by calling 1-800-206-9333 or by emailing Departments employees can then verify whether the plant is indeed cogongrass and take action.

“If a landowner suspects they have cogongrass, we ask that they alert us so we can confirm the identification and treat it,” Driscoll said.