Japanese Stiltgrass

If you drive along the shady, back-roads of Bucks County you’ve seen Japanese stiltgrass. It is the green grass growing on the road sides. While it provides a pretty fringe to the roadway, this is a nasty invasive plant. One of my early encounters with it was when a naturalist at Bowman’s Hill Wildflower Preserve called about 20 years ago to ask me what could be done to control it. It was crowding out the dainty wild flowers.
Japanese Stilitgrass, Microstegium vimineum, is a summer annual grass that is native to Asia and was probably introduced to the U.S in the early 1900’s. It germinates in early spring and dies each fall when we have a killing frost, surviving only as seed.
Stiltgrass has a lot in common with crabgrass. Same life cycle. In fact, most of the controls used for crabgrass, chemical and non-chemical, work for stiltgrass. Stilt grass appears to be much more shade tolerant than crabgrass which is why it creeps in corm those shady areas and into garden beds and lawns.
Establishing dense, competitive turf is the answer where stiltgrass threatens lawns. . Use a shade tolerant grass species such as fine fescue in shady areas and fertilize to keep it dense. Apply a pre-emerge crabgrass control product in early April to prevent stilt grass germination. In landscape beds, preemerge herbicides will do the trick or you can simply pull and mow it all season.
Unfortunately, in unmanaged areas it will continue to dominate those fringe spaces, crowding out other plants.