
Utter the words “Japanese knotweed” to a homeowner and all the blood is likely to drain from their face. They may break into a cold sweat, eyes darting around frantically as they grab your shoulders and shake you, shouting: “WHERE??”
The notorious weed was first introduced into the UK by German-British botanist Philipp von Siebold in the 19th century as an ornamental plant, for its large, heart-shaped green leaves and hollow stems, with clusters of small white flowers that bloom in late summer. Its import proved to be disastrous. Without the checks and balances of its native land that kept it under control, the knotweed thrived in the UK, growing stronger, larger and more fiercely.