Garden Diary: Battling Japanese Stilt Grass

Every summer an invasive grass fills my garden like a gently rising flood. Until mid-summer it's hardly noticeable, then suddenly it springs up to two or three feet, thick masses that lean over and flatten in rain, literally swamping smaller plants. The annual guerrilla action of Japanese Stilt Grass (Microstegium vimineum) sends me into periods of depression and despair alternating with hope for its eventual eradication.

Most agricultural research in the U.S. offers limited measures for control of large areas of infestation. There are three methods for control: use of herbicides, hand pulling late in the season (late to limit time for regeneration from the seed bank), and mowing late in the season (early mowing seems to promote rapid regrowth and seed formation).

Fortunately this is an annual grass, so it should be controllable with a preemergent or some other herbicide applied later in the season. Since I rely on seeded plantings to be an important part of my garden, particularly for weed suppressing groundcover, I'm reluctant to use a preemergent. For the same reason, I'm reluctant to use herbicide later in the season.

Last summer I tried mowing in early fall, but not early enough I'm afraid, because seed formation already had begun. This summer, I'll try hand pulling, which is quite easy in wet ground but a real chore over an acre, followed by mowing. Yes, I'll also mow the first year seeded plants, but most of those will probably not be harmed and will return the following year with more vigor.

If anyone who reads this has had any success eradicating Japanese Stilt Grass, I'd appreciate hearing how you did it.

And that photo at the top? It's not my garden.