Knotweed

Polygonum aviculare

Knotweed is a common summer annual broadleaf weed that is often referred to as Prostrate Knotweed, Knot-grass, Door-weed, Mat-grass, Pink-weed or Bird-grass. Its scientific name is Polygonum aviculare.

Identify

Alternate

Entire

Elliptical

Knotweed can be identified by its lateral growth patterns and ascending, branching stems. This broadleaf weed typically grows with its branches in a tough, wiry mat that rises only a few inches above the soil. On some occasions, Knotweed can grow vertically, usually in lawns receiving more shade. Knotweed stems are slender, branched and swollen at the nodes, and its taproot is thin.

Life Cycle

Although it's normally one of the first summer annual broadleaf weeds to emerge in the spring, it can also emerge throughout the spring and summer. Knotweed can grow in areas of lawns receiving a balanced mix of shade and sunlight but requires moist soil to germinate.

Control

Although hand-pulling can be an effective short-term method for removing Polygonum aviculare, it is not the most effective solution. Knotweed reproduces by seeds, which are extremely small (less than 1/25 of an inch). hand-pulling can disrupt the seeds from their pods, spreading them in your lawn. Professionally selected and applied broadleaf weed killers—based on your specific climate and geography—are the most effective method for control.