Knotweeds (Reynoutria syn. Fallopia spp.)

Knotweeds (Polygonum polystachyum syn. Koenigia polystachya)



Robust herbaceous perennials with hollow stems growing up to 1-5 m tall in dense thickets.  Small white inflorescences branch out from leaf axils in showy plumes.


This collection of Asian ornamentals form monocultural colonies in sunny areas.  On Galiano Island, they are uncommon on disturbed sites in rich soils.


Knotweed is capable of growing through concrete and asphalt, and forms dense monocultures that completely exclude native species.  It causes erosion in riparian areas.


Do not plant or transport knotweed.  Once a population is established, herbicide is necessary to remove it. Digging and mowing should only be performed if (a) the population is small enough to allow for complete removal, and (b) all material is bagged and disposed of appropriately in a landfill.

Our Experience

Prevention is the best approach to limit the spread of knotweeds.  Established populations should be removed by professionals wherever they occur.

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