The plastic need to prolong 5 to ten ft outside the house the boundary area with the knotweed advancement. Use rocks or other heavy products to weigh down the tarps, so they don't shift or blow absent. As this masking will need to stay in position for years, disguise it https://japanese-knotweed-control44219.blog2freedom.com/37879604/5-simple-statements-about-japanese-knotweed-control-explained