Japanese knotweed is native to eastern Asia and was first introduced into North America in the late 1800s. It was used as an ornamental plant on properties and also for erosion control due to its deep and interwoven root system.
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.
Knotweed Help is a trading style of Cobleys Solicitors Ltd
Japanese Knotweed patches turn brown and appear dead In winter
When trying to differentiate Japanese knotweed leaves and Hybrid knotweed leaves, take a close look at the edges. Hybrid plants tend to have crinkled edges, whereas the original plant’s are smooth. Japanese knotweed leaves also tend to be a lighter shade of green and have a broader base (which some describe as more shield-like), whereas hybrid leaves have a more accentuated heart-shaped profile. You may also notice fine trichomes or hairs on the underside of hybrid leaves whilst Japanese knotweed are hairless underneath .
As accredited knotweed experts, we’re well-versed in all Japanese knotweed identification methods as we provide a free and reliable identification service. If you’d like this free Japanese knotweed identification service, please fill in our contact form at the side of this page including images of the potential infestation. To help you correctly identify Japanese knotweed, we’ve also produced a clear succinct guide that highlights the most reliable ways to recognise Japanese knotweed below.
On this page, we’ll look at how to identify Japanese knotweed, characteristics of Japanese knotweed, different types of Japanese knotweed, plants that look like Japanese knotweed and many other Japanese knotweed related topics and subtopics.
Young Japanese knotweed shoots are typically brown with specs of dark green
Japanese knotweed has a robust root system that is comprised of a network of rhizomes. These tough, woody roots can be collected together in large crowns which can be difficult to remove from the ground without the help of machinery. Japanese Knotweeed Rhizomes are dark brown on the outside and orange on the inside, you can usually break them in your hands unless they have grown into a larger clump or ‘crown’ .