Japanese knotweed


I have some Japanese knotweed. But I’m not sure what type of this weed



Thankyou for contacting the Toronto Master Gardeners.

To help you confirm the identity of your plant, some excellent and clear images of Japanese Knotweed are included in the link to Ontario Invasive Plants Council’s site below. The plant has pretty white flowers,  heart  shaped leaves with prominent veins, hollow, jointed stems with reddish brown solid nodes (looking similar to bamboo) that die back each fall leaving  dead stalks standing over the winter. New growth from some of the lower nodes along with new stems from the over-wintering root system emerge in the spring.  The plant grows very rapidly – up to 8 cm (3 in.) in a day and reaches a mature height of 1-3 m (3-10 ft.) by the end of July. It is considered highly invasive.

If you want  to control it and you have just a small patch, you can try digging it out including all roots and rhizomes ( the underground roots and stems) but since it is almost impossible to dig out the complete root system , another way to approach controlling it is to  try cutting it off at ground level,  repeatedly – multiple times over the course of the season whenever you see new growth . You can expect to do this for several (perhaps up to 5) years but the cutting will weaken and eventually kill the root system.  This approach is recommended as, as mentioned ,it is almost impossible to eradicate the complete root system and is also less destructive if the plants are growing in a garden bed.  Some excellent images to further help you identify your plant as well as a description of the impact of larger infestations, and how to deal with them is covered on the Ontario Invasive Plant Council’s site at the following link: (Scroll down to  “Mowing , Cutting and Digging “.)


You may also find the information from one of our earlier posts to be of interest:



I hope this has been helpful