I have a huge Japanese knotweed in my side yard. It is popping up all over. How do I get rid of it?
Japanese Knotweed is difficult to get rid of unless you dig up all the roots and dispose of them, or patiently and repeatedly cut down the stalk of the knotweed until the roots are exhausted of energy and nutrients and it fails to return again. The City of Toronto suggests cutting down the Knotweed stem at the base once it has reached 5-6 feet, but before it flowers, to deplete the most energy possible from the roots and not allow it to reproduce. Repeat cutting the plant in early August and in early September. I would do a combination of trying to remove as much of the root system as possible, and then wherever the plant sprouts up again.
A city reference for you to read: www.toronto.ca/trees/pdfs/TOIslandInvasivesDistributionVersion.pdf