Click below to listen to my Garden Bite radio show: Japanese Knotweed
Japanese Knotweed sounds fairly innocuous but I’m here to tell you – it’s not. The plants appearance is pretty lovely with heart-shaped leaves, bamboo stems and dainty, little white-flower tassels. What may be hard to see at first is it’s killer instinct, that according to one article I read!
The weed sometimes referred to as Fleeceflower can be found in 39 States and is listed as a noxious/invasive weed from New York to Colorado and up into Alaska. Europe is also looking to eradicate the Japanese invader. In Australia, it is illegal to have any of this species growing on your property.
Japanese knotweed has a large underground network of roots (rhizomes). To eradicate the plant the roots need to be killed. All above-ground portions of the plant need to be controlled repeatedly for several years in order to weaken and kill the entire patch. Picking the right herbicide is essential, as it must travel through the plant and into the root system below.
glyphosate is one of those herbicides but these methods haven’t been proven to provide reliable long-term results. Digging up the rhizomes is a common solution where the land is to be developed, as this is quicker than the use of herbicides, but safe disposal of the plant material without spreading it is difficult.
For more information see USDA Invasive Species
It gets tall!