11/09/2026
It didn't arrive as a pest, it arrived as a prize. A German doctor, von Siebold, sold it from his Dutch nursery as a fashionable ornamental, and in 1850 a shipment reached Kew. The Victorians loved the bamboo-like stems and fast cover, and planted it across gardens and estates. That's the origin of nearly every plant we now fight.
It's a single female clone that can't set seed, so it doesn't spread by seed, it spreads by soil. A fragment of root under a gram, carried in a bucket of muck or a load of spoil, is enough to start a fresh infestation.
You'll often hear the Victorians planted it to reinforce railway embankments. That may be true in part, but the actual evidence it was planted for that is thin. The likelier reason it hugs the railways is boring: railways shift huge volumes of soil, and every load risks carrying a fragment.
And that's exactly why it's a construction problem, not a gardening one. Moving soil is what spreads it, and moving soil is a large part of construction. So it can arrive on site in imported fill or disturbed ground, and it gets found later. By then it's a delay, a remediation cost, and a dispute over who knew what and when.
Know what's on your site and what you signed before you start.