No photo available yet
Submit a photoJapanese Knotweed
Reynoutria japonica
⚠️ PROHIBITED NOXIOUS — must be destroyed. A hollow bamboo-like perennial (2–3 m tall) from East Asia with heart-shaped leaves and sprays of small white flowers in late summer. Notorious for pushing through concrete foundations, asphalt, and building walls. Roots can extend 7 m sideways and 3 m deep. Extremely difficult to eradicate — fragments as small as a fingernail regrow. Never attempt to mow or till.
Quick Facts
Distribution
Scattered in Alberta, especially urban areas; spreading
Light
Full sun to part shade
Bloom Time
Aug–Sept
Soil
Adaptable — thrives anywhere
Water
Moderate to high
Growing & Cultivation
Propagation
DO NOT PROPAGATE. Control: repeated glyphosate stem injection over 3–5 years is the standard professional approach. Do not compost or move soil from infested sites — rhizome fragments spread the plant.
