Nimblewill is a warm-season perennial weed found throughout North America east of the Rockies. Nimblewill (Muhlenbergia shreberi) invades cool-season grasses by both seed and stems. It has a shallow root system.
Nimblewill is a perennial that goes off color with cool weather. Where the turf is not fertilized, nimblewill becomes aggressive. Nimblewill is more aggressive in shaded areas. Turf that is mowed low will resist the invasion of nimblewill. Nimblewill is more aggressive in moist rich soil.
Thick sod reduces the opportunity for it to take hold, however, in thin areas, or surrounding garden beds, it can quickly spread into lawn areas. Remove the plants by pulling out by hand. Nimblewill sets seeds in early fall; then lay dormant until next spring.
Once it takes hold there is no selective control for removing it from the lawn. Must use a non-selective herbicide that will kill all plants, then reseed area such as Roundup.
Other common names of this plant are drop-seed and wire-grass.
Nimblewill spreads from area to area by seeds and spreading stems
Nimblewill forms dense patches, often a 1' or larger by spreading stems. It has fibrous roots and the stems often root at the lower nodes
Nimblewill produces blue-green, short, flat leaves up to 2" long
Long slender flower stalks appear in late summer
Nimblewill tolerates both sun and shade and is often found in moist conditions
The cultural conditions that favor nimblewill are usually hot, full-sun with low maintenance inputs. It may be possible to limit the spread of nimblewill by fertilizing the cool-season turf in the spring and fall when the nimblewill is dormant.
Due to the perennial nature of nimblewill and its well-developed stolon system it is very difficult to remove by mechanical means. Methods include digging up the offending patches, including several inches of soil and replacing with new topsoil and reseeding. However, any stolons that remain can potentially develop into new plants.
This method uses clear plastic fastened securely to the ground over the nimblewill areas. Be sure to cut the plastic slightly larger than the patches. Leave the plastic in place for 5-7 days in the spring or summer when the weather is nice. The plastic will trap heat close to the soil surface and hopefully devitalize the plant material. After removing the plastic you may reseed the area. This method can be very effective for nimblewill because the vegetative tissue is close to the surface.