Department of Parks and Recreation
Japanese Stilt Grass Alert
Japanese stilt grass (Microsteguim vimineum), is an INVASIVE grass. It is notorious for invading forest understudy and crowding out native plants, including young trees, essentially taking over all available growing space. Deer don't eat it and it is difficult to control once it is well established. We are trying to keep stilt grass out of Arlington 's natural areas. If you have this grass on your property, PULL IT UP!
Identifying characteristics:
- Lime green color
- Bamboo-like appearance
- Subtle silver streak in the middle of the blade
Japanese Stilt grass (Microstegium vimineum)
Where did it come from?
Japanese stilt grass is from - you guessed it – Japan , and other Asian countries including India, Nepal and China. Stilt grass was used as a packing material for porcelain from China in the 1900's and people think seeds in the packing material were unintentionally introduced to North America. Herbivores or other limiting factors are likely keeping it in check in its native Asian range and preventing it from growing out of control.
What is the problem here?
It appears that few factors are keeping Japanese stilt grass in check here. Japanese stilt grass spreads rapidly especially in areas that have been disturbed. Unlike most grasses, it can grow prolifically in the shade and densely cover the floor of a forest, thereby preventing the growth of other plants including young trees and shrubs. Our animals and insects don't seem to have a taste for it. It is difficult to get rid of once it covers large areas.
What does it look like?
Stilt grass is lime green in color. Blades have a subtle silver streak that runs down the blade slightly off center. It also has tiny “stilts” that run off the stem near the root like the stilts on corn stalks. Some people call it “little bamboo” because a clump of stilt grass resembles a tiny stand of bamboo.
What can I do to help?
Stilt grass is found in relatively small patches in Arlington compared to some surrounding localities. We would like to keep it that way. 
Stilt grass produces many seeds that disperse easily. You can help prevent stilt grass from producing seed especially in small patches near forested areas. If you have stilt grass on your property, the best way to get rid of it is to pull it up. Stilt grass has a shallow root system so it pulls up easily. Pulled grass will die quickly if it has a chance to dry out. For larger patches, you may be able to control it by mowing it to a short length in early September to prevent it from producing seed heads. Watch your mowed area closely to make sure it doesn't flower. If it does produce tiny flowers on the end of the blade, mow it again as soon as you see flowering. Another option for large patches is herbicide treatment. Spray the patch with a herbicide containing the active ingredients glyphosate or sethoxydim. Read the label for appropriate concentration. Be careful not to hit desirable plants with herbicide. Glyphosate herbicides affect all plants and sethoxydim herbicides affect grasses. You will probably just need to use one herbicide but many have to do several treatments over time to kill all remaining patches and regrowth.
Japanese stilt grass seeds may be viable for several years so expect to continue treatment for a few years. If treated correctly, and new seeds are not introduced the patch should become smaller and less dense over time.
Stilt grass readily invades areas where soil has been disturbed. Try to minimize soil disturbance in construction and gardening projects. If you do disturb the soil, watch that area closely so you can eliminate stilt grass and other invasive plants if they are appear.
Can I volunteer to remove stilt grass in Arlington County Parks?
Yes, absolutely you can! We appreciate any help we can get to help keep stilt grass out the parks. Call (703) 228-7636 to find out how you can help.
Where can I learn more?
To learn more about Japanese Stilt Grass, visit these websites:
- Alien Plant Facts for Japanese Stilt Grass - National Park Service
- Arlington Department of PRCR: Invasive Plant Program
- Become a RIP Volunteer!
