Wigan's terraced streets often have small flagged yards opening onto shared alleys. Knotweed finds its way through joints in the flags, along the base of walls and under gates.
Signs
Red shoots between flags in spring, a clump of tall canes in a corner in summer, or dead brown canes in winter.
What to do
Leave it alone, take a photo and send it to us. If it is knotweed, the survey will show how far it reaches under the yard and into neighbouring ones.