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What is Japanese Knotweed? An Illustrated Guide

Japanese knotweed is a highly invasive weed that is difficult to kill. It has quickly taken over many areas of the country including the waterways of eastern states such as North Carolina, New York, and New Jersey. As Japanese knotweed continues to invade the coastal waters of the US, it’s a good idea to arm ourselves with the right information so that we can better understand how this weed operates. Unlike killing other weeds, knotweed is a bit more difficult to eradicate.

How big can Japanese Knotweed get?

This is crazy but Japanese Knotweed can grow up to 3 inches a day and can reach up to 10 feet tall. The roots can send shoots up to 70 feet away from the nearest stem, and the roots can dive as deep as 20 feet!

How can identify Japanese Knotweed?

Japanese knotweed is fairly easy to identify with its green heart-shaped leaves, its stems are speckled with purple dots which are on its bamboo-like, segmented stems. From August to September knotweed will produce creamy white flowers. 

What kind of damage can Japanese Knotweed cause?

Knotweed can cause damage to the foundation of homes, can break apart concrete and asphalt, can negatively impact a home’s value, and they can even clog, crack or break drain pipes. 

How can I protect my home from knotweed?

If knotweed should become present in your lawn; cut the stems down to the ground, dispose of clippings, cover the area with a tarp, and consult with a professional to see what other steps can be taken to eradicate the weed.


At the end of the day, Japanese Knotweed is an invasive, fast-spreading, difficult to eradicate weed that should not be overlooked. For more information on Knotweed Check out Tar heel Basement Systems. And be sure to check out our lawn care and home maintenance blog for more great info. 

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