- Japanese knotweed shoots are capable of growing through tarmac and concrete.
- A piece of rhizome less than 0.7g, smaller than a fingernail, is capable of growing into a new plant and starting a new infestation.
- The plant is so resilient it is even immune to burning and can rise from the ashes to grow once again.
- Japanese knotweed can grow up to 40mm per day during late spring/early summer.
- It is estimated that there is at least one infestation of the plant in every 10km2 in the UK.
- The biggest cause of the Japanese knotweed spread is fly-tipping.
- Japanese knotweed has been known to spread after travelling from machinery used on building sites.
- The plant stores nutrients in a maze of roots underground thus enabling it to hibernate in the winter months.
- Dead Japanese knotweed stalks and stems can take up to 3 years to fully decompose.
- Japanese knotweed is a distinctive plant and early identification is essential to prevent further contamination. The weed assumes various states through the year which can make it difficult to identify. To the untrained eye it can seem quite unassuming, even pleasant.
The first signs of Japanese knotweed growth are distinctive red and purple shoots.
These are often accompanied by rolled back leaves which grow rapidly from the stored nutrients in the rhizome.
The stem resembles bamboo, though more green in colour with purple speckles. Inside, the cane has distinctive chambers that retain water and nutrients.
As the first frost appears, the plant’s leaves turn brown. During this period Japanese knotweed withdraws back into its rhizome.
The canes lose colour and turn into woody stalks which can take years to decompose.
New shoots can be found growing through the dead canes in the early Spring.
Legislation: Law & Acts
Japanese knotweed is governed by numerous laws and acts concerning the way in which it is treated and disposed of, due to its damaging ability to spread aggressively if mishandled.