Growing Japanese Knotweed / Fallopia japonica

In the UK people have trouble getting get homeowner's insurance if they have this growing on their property. If you seal off an area with a tarp or concrete on top, and seal off six feet underground on every side, then it still takes 20 years for the rhizomes to die. I strongly discourage you from growing this plant. "Invasive" is an understatement for the devastation it can cause an ecosystem.

That said, in many places it's extremely easy to find and could be wild-harvested in a basically unlimited amount. Where do you live?

Normally I would be cheering you on for growing your own anything. I love herbal medicine and gardening and everything about this question! I just did a lot of research on JK while house hunting recently and actually backed out of a purchase because of a stand of JK growing on the property. It's just too hard to control and mitigate.

Depending on where you live there's a fair chance it already grows nearby. I'm in the northern panhandle of WV and it grows everywhere around here. I see it in Pittsburgh too. Grows along the Ohio River and any and all streams around here plus fields etc. Can literally grow anywhere.