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.

Autumn light: confirmation

A group of Calamagrostis acutiflora 'Karl Foerster', Miscanthus purpurescens, Panicum virgatum 'Dallas Blues', and Panicum v. 'Shenandoah'.

Following several days of intermittent, heavy rain, the early morning sun is backlighting a group of grasses in my Federal Twist garden, confirming my plans to add other groupings of grasses that echo one another in an apparently random, but complementary, way.

The forms and colors of each grass stand out against the dark backdrop of the woods, and the backlighting brings out the character of each. The fluffy, white plumes of Miscanthus purpurescens add an especially natural feel to the planting, almost like white smoke, and contrast with the more formal calamagrostis. The Panicum 'Dallas Blues' has begun its turn toward pale yellow, which I remember will darken to a rich russet throughout winter.

We are nearing the end of the second year of planting, which has been slowed by need to control invasive weeds - the worst is a smothering blanket of Japanese stilt grass (Microstegium vimineum), with enough poison ivy and multiflora rose to cause additional trouble - and by my budget. So as winter nears, planning for next year's planting begins (I should say "continues").