Japanese Stilt Grass, a Prolific Invasive Plant in Connecticut

The transition area between our front lawn and adjacent woods is a ‘wild’ area filled with woodland grasses, ferns, and mosses – lovely and very low maintenance, until now.  Last July I identified Japanese stilt grass in a section about six to eight feet wide and long. Japanese stilt grass is a truly scary invasive that is overtaking roadside edges, drainage culverts, and wooded areas in my neighborhood and elsewhere in Connecticut.

Japanese stilt grass spreads by seeds and possibly resprouts from rootlets not completely removed when pulling the plant.

This is what Japanese stilt grass looks like now, at the end of May on my Connecticut property.

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Here it is even closer.

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It doesn’t appear to be troublesome at first. It looks unassuming in the foreground below.

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It’s actually a rather attractive low-growing plant that holds a lime-green shade all summer long. But don’t be fooled by its mild-mannered look. Left alone it will fill in so thickly that native grasses and other plants will be smothered. In the same area it looked like this last August.

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Normally, Japanese stilt grass germinates in June. This year it germinated in May. Normally Japanese stilt grass blooms in August. This year watch for it to begin blooming in July. One plant … one of these thin stalks of greenery … typically produces about 100 seeds. Seeds remain viable for about seven years. Do the math. One stalk can cause 100 more stalks any time during the next seven years.

It has, does, and will spread.

We followed advised control steps: weed whacked it before it began to bloom and let it dry and remain in place. Any raking disturbs underlying soil and brings seeds to the surface to sprout. We left the area alone till Autumn. No new plants showed up.  Then we spread wood chips harvested from some of the felled trees on our property.

This year the stilt grass is back, presumably from seeds that must be in the soil. There must have been some in the area in previous years that went unnoticed and seeded. I’m pulling as much of the stilt grass as possible without moving the wood chips aside. I don’t plan to let it get as thick as it was last year. Continued pulling will have to continue throughout the growing season.

Pulled plants should be placed in a container and sent away with the trash. Ideally, to be sure the plants are degraded fully, let them sit in a plastic bag in the hot sun for a few days before throwing the bag in the trash. Do not compost Japanese stilt grass. It is not clear that home composting gets hot enough to kill it off. Do not throw Japanese stilt grass into the woods thinking it will die off; it may regrow from rootlets.

If you find this plant in flower beds, do not ignore it. It will quickly become a major problem.  Read UConn’s Invasive Plant Worksheet for more information.

Garden thoughtfully …

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3 comments for “Japanese Stilt Grass, a Prolific Invasive Plant in Connecticut

  1. May 29, 2012 at 8:34 am

    I have my eye out for all the usual invasive suspects around here, but I did not know about stilt grass. I am not sure if I’ve seen it — it does look “ordinary” and like a lot of other grasses. With this info now, I’ll have to see if I have Japanese stilt grass invading anywhere near me. Thanks for the info. ugh.

    • May 29, 2012 at 9:34 am

      Laurrie, you’ll really want to aggressively controll Japanese stilt grass if you find any. Hope you don’t.

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