Invasive Plants

Japanese Knotweed

Japanese Knotweed, Reynoutria japonica


Sometimes referred to as bamboo, Japanese knotweed is found across PEI. It is a very invasive plant, native to Asia, that out-competes other plants, creating a monoculture.  This reduction in plant biodiversity reduces wildlife habitat and food, resulting in fewer wildlife species being present.

Japanese knotweed is a non-woody, perennial plant that dies back to the ground each year and can grow up to a height of 3m annually.  It spreads mainly by underground stems (rhizomes).  These rhizomes can grow 20m horizontally and 3m down.  They cause issues with infrastructure and can even come up through pavement!

At Victoria Park in Charlottetown, we experimented with different ways to manage knotweed patches (cutting the knotweed to deplete the supply of food in its rhizomes, laying down tarps over the knotweed patch and putting soil on top of some of the tarps).  Black tarps created a lot of heat which “cooked” the the shoots but still allowed the plants to grow. The tarp that was covered with the soil created dense shade and prevented and water from getting to the knotweed plants.  There was no green growth under the tarp/soil combination.  

There are various other ways to manage Japanese Knotweed, including regular mowing to prevent its spread and herbicide use, if done responsibly and following regulations. 

You can help stop the spread of invasive plants. If you have this plant growing on your property, please do your part to manage it and protect PEI's natural environments.