Reproduction occurs both by rhizomes (lateral growing roots) and seeds, making this plant extremely hard to eradicate. The plant has also been known to reproduce simply from cuttings which allows for many means of dispersion.
The stands are so dense that they shade out other plant species, reducing wildlife habitat for native species. This plant is extremely hard to eradicate once established, so the key it preventing establishment by manually removing immature clusters. Along river banks, the shallow root growth can cause unstable banks, which is exacerbated by knotweed dying back in the fall.
As previously stated, knotweed has the ability to regrow full plants from its cuttings as well as from its rhizomes (root structure) and seeds. Due to this, knotweed cannot simply be cut down, but must be dug up with the entire root structure and disposed of fully. Plants should be removed from the site and either disposed of in black plastic bags, or at the town composting facility. A "cut-and-dab" approach can be used if woody root can be exposed. Foliar spray is not recommended as it can be harmful to the surrounding floura and fauna. See the invasive removal page
for how to carry out these methods. Any removal within 100 feet of wetland resource areas, including certified vernal pools, or within 200 feet of a perennial stream may require approval from the Concord Natural Resources Commission. Please contact the Division of Natural Resources before you begin.
The following native plants can serve as a good replacement to knotweed in a garden:
New England Aster (Aster novae-angliae)
Blue False Indigo (Baptisia australis)
Sweet Joe-Pye-Weed (Eupatorium purpureum)
Queen-of-the-Prairie (Filipendula rubra)