Containing Japanese knotweed with root barriers

Root barriers can be used to contain Japanese knotweed growing either laterally or vertically.

Vertical root barriers are typically used at boundaries to prevent encroachment to or from adjoining land. They are installed to a depth of 2-3m depending upon the depth of the knotweed rhizome. A trench is dug with a mechanical excavator and the root barrier positioned prior to backfilling with appropriate fill material.

Horizontal root barriers can be used to protect specific surfaces such as roadways, drives etc. where it has not been possible to remove all Japanese knotweed rhizome. The root barrier simply forms a barrier, which actually encourages more lateral spread. A sacrificial zone is usually provided at the edge of the root barrier, such that if new growth does appear it can be treated with herbicide.

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"a useful means of containing knotweed at boundaries to prevent encroachment and to protect specific surfaces such as asphalt, driveways, etc from new knotweed growth"