Japanese Knotweed


Bamboo-like jungle forming with green hollow vertical stems with purplish joints.


Spreads from the “knots” or underground rhizomes and root systems, also by seed, also dispersed by floods or disturbance of the soil. A tiny bit of rhizome left in the soil will sprout a new plant. It is monoicious so does not require male-female plants in order to reproduce. Will advance on foundations and asphalt driveways.

It is partially edible; see newsletter article with recipe idea here.


Once established extremely difficult to eradicate without professional treatment. Dig rhizomes (cut the rhizomes and root parts off the green stalk, and dispose as trash) or cut at base (lop or scythe) 3-4 times a year, each time letting it grow 3-4′ before cutting, to exhaust and shrink the rhizome.

When controlling a large area, work from the edges in (to stop further spread)!  Dig and pull the edges and work towards the center, cutting center if no time/labor to pull/dig.  A multi-prong approach, that may also include professional chemical treatment, may be necessary.

Links and Resources

For more information on how to identify and control Japanese knotweed, please refer to the resources below:

  1. Mass Audubon for identification
  2. Penn State Extension for identification and control
  3. Invasive.org for identification and control
  4. Newsletter article on edibles here