Japanese Knotweed is a robust perennial with bamboo-like stems and heart-shaped leaves. It is highly invasive and can grow through concrete, causing damage to infrastructure. It spreads rapidly, forming dense thickets that outcompete native plants.
Best time to see a Japanese Knotweed
The best time to see a Japanese Knotweed is April–August, when about 68% of U.S. sightings happen, based on 35,820 research-grade iNaturalist observations.
Not certain it is a Japanese Knotweed? What plant is this? walks through what to check first and the lookalikes that catch people out.
Recent Japanese Knotweed sightings near you
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