The Old Town and parts of Weston are full of sandstone retaining walls and narrow rear alleys. They are part of the character of the place, but they also hide what grows at their base, and knotweed can sit unseen for years before it pushes through.
The signs
Red-purple shoots at the foot of a wall in spring, a stand of tall canes above the wall line in summer, or dry brown canes in winter.
What to do
Leave it, take a photo and send it to us. If it is knotweed, the survey shows how far it runs under your garden and into the next.