Japanese stiltgrass looks a bit like a miniature bamboo. Not the tall variety that you get bamboo poles from but one of the smaller varieties. Stiltgrass only gets at most about 6-8 inches high but if not controlled, it can get up to two feet high. To see a picture, click here.
Annual but Long-Lived Seeds
It is an annual, so that makes it slightly easier to deal with. However, the seeds can be viable for years, so if you pull them and they are close to going to seed, don’t compost them. You will regret it next year.
Remove by Weeding / Pulling
Luckily, they barely have any root structure at all so they are easy to pull up. They appear in the summer but grow extensively in the fall. Pull them before they can go to seed. Pull the weed after a rain or wet the area you will be weeding. This goes for any weed. It is much easier to pull them and have the roots come to when the soil is wet. When it is dry, they tend to snap off and leave the roots in the ground and you will just have to come back and do it all over again.
Stiltgrass likes moister and shady conditions which grass doesn’t do too well in. You can condition the soil to make it better for your grass so it can compete better with the stiltgrass. You could also help things by doing some pruning of trees in the area to get more sunlight to the ground.
If the soil is too moist, core aeration can help. Also, once the stiltgrass is pulled, you should put down something to prevent the seeds from germinating. A natural product is corn gluten which should be put down in the spring. Or you could use Preen. You might want to retreat after 3 months with either Preen or the corn gluten.