Identification of Japanese Knotweed

(Question)

Hello, was wondering if you could tell me if this is Japanese knotweed and if so what is the best way to prevents it’s spread.

another question, i moved into a new place and Lilly of the valley has taken over a large part of the garden. Should I try to contain it or is it better to prevent any future headaches and just rip it all out.

Thank you for your time.
H

(Answer)

Hello, –The Ontario Invasive Plant Council describes the stem of Japanese Knotweed as Hollow, jointed stems have reddish brown solid nodes and look similar to bamboo.Your photo certainly looks like Japanese Knotweed (Fallopia japonica).  The stems die back each fall and the dead stalks remain 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.  If your photo shows the full extent of your Japanese knotweed, that is, just a small patch, you can control it by cutting it off at ground level. You will need to do this repeatedly – multiple times over the course of the season and for 3-5 years.  The cutting will weaken and eventually kill the root system.  This approach is recommended as it is almost impossible to dig out the complete root system and is also less destructive if the plants are growing in a garden bed.  The impact of larger infestations and how to deal with them is covered on the Ontario Invasive Plant Councils site at the following link:

http://www.ontarioinvasiveplants.ca/wp-content/uploads/2016/06/OIPC_BMP_JapaneseKnotweed.pdf

As for the lily of the valley, its another plant that is almost impossible to get rid of or contain. I am fond of the scent of lily of the valley so in my garden I try to restrict it to certain areas where its hard to grow other plants but it still pops up in most of my beds. Youll need to decide whether you want it in your garden or not and if not like Japanese Knotweed, it will be a multi-year effort to get rid of it.  I recommend cutting the plants off at ground level rather than pulling as you can rarely get the whole root and breaking up the root stimulates additional growth. Good luck!