Japanese Knotweed is a highly invasive weed RHS Advice on Japanese Knotweed RHS Advice on Japanese Knotweed Japanese knotweed Japanese knotweed RHS Advice on Japanese Knotweed RHS advice Japanese knotweed "Japanese knotweed" “RHS on Japanese Knotweed” https://www.rhs.org.uk/advice/profile?PID=218 RHS Advice on Japanese Knotweed Japanese Knotweed