Japanese stiltgrass (Microstegium vimineum), an invasive grassy weed native to Asia is one of the most destructive weeds in our landscape. It is also one of the hardest to control. But with the proper steps, not impossible. Left unchecked, it is a real threat to our native species. It grows in shady, moist areas along stream beds and edges of woods, From there it can spread into lawns and planting beds. Because it grows in clumps, it can easily overtake the existing area.
Japanese stiltgrass is a grassy annual weed, growing new each year from seed and dying with the frost. It can grow up to 3″ tall and spread rapidly. A single plant can produce up to 1,000 seeds which can stay viable for 5 years. Deer and other animals avoid it and would rather eat the native plants which makes its spreading more concerning.
So how can it be controlled? Because it is an annual, stiltgrass can be attacked in several ways. A preemergent can be applied to prevent germination. The same ones that work on crabgrass will work on stiltgrass. They include Halts (pendemethelin), prodiamine, and even corn gluten in the landscape and trifurilin (Preen) in flower beds. However, it must be applied several weeks earlier than for crabgrass (mid to late March). Herbein’s has these products available for your convenience. Post emergent is harder to control. Regular crabgrass killers are ineffective. Hand pulling is possible for small areas but not practical for larger ones. Mowing will help with proper timing. It must be mowed just prior to setting seed (about mid-August) or else it will just encourage a more rapid growth. Products like Bonide Grass Beater and Ortho Grass B Gon will work in beds. For larger areas, a glyphosate (Roundup, Kleenup) product can be used. Directions must be followed especially around water. Acclaim an also be used bu can be rather expensive.
In closing, Japanese stiltgrass is a problem weed that takes time and persistence to control.
Your friends at Herbein’s are willing and ready to help.