Japanese Knotweed typically spreads as a result of the plants’ stems, or rhizomes (underground roots) being moved and spread around. Only the female form of the plant is present in the UK and therefore, it cannot pollinate and produce any viable seed, other than hybridising with other similar Knotweed species.
Trials have shown as little as 0.7 grams of rhizome material, which is smaller than your little finger nail can produce a new plant within 10 days.
Find out more about Japanese Knotweed, how it came to the UK and how it grows, on our page What is Japanese Knotweed?