The history of knotweed

So, who’s to blame for inviting this enraging weed into our yards?

The short answer is Philipp Franz Balthasar von Siebold*. A German physician and explorer, von Siebold volunteered for the Dutch military because he loved traveling and had a deep interest in horticulture. Eventually stationed at a trading post in Nagasaki Harbor at a time when foreigners were forbidden to enter Japan’s mainland, von Siebold charmed his way into the country. He made a name for himself and collected an enormous trove of botanical material. He was kicked out of the country in 1830 but exported much of his collection and published the celebrated Flora Japonica in 1835. Along with treasured plants like the hosta, various hydrangeas, and varieties of azalea, came Fallopia japonica, the dreaded villain of our story. Commercially available in Europe by 1848 and advertised as an ornamental shrub, knotweed received a warm welcome into private gardens across the European continent. It was recorded in the United States by 1873. Its campaign of terror was underway.

It wasn’t long before knotweed had overstayed its welcome. By the 1890s, perceptions of the plant had dramatically changed. Knotweed had spread outside private gardens, property owners viewed it as an unwanted invasive, and it was no longer widely advertised. Unfortunately, the damage was done. Within a decade, knotweed was choking private and public lands throughout Europe and the United States. While its presence has only worsened, there are some glimmers of hope. Public awareness, organized efforts to address infestations, and new treatment methods are beginning to show some positive results. Time will tell.

*Despite giving knotweed a free ride to Europe, Philipp Franz Balthasar van Siebold has a pretty amazing story. It’s worth reading about.