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Knot in my backyard

Japanese Knotweed (Fallopia Japonica), while once appreciated as an ornamental plant is now known to cause severe damage to property, reduce land value and be expensive to treat.

This perennial and extremely invasive plant has the ability to grow through tarmac and concrete and damage the foundations of property. The smallest piece can re-grow and spread both by natural means and human activity.

Causing the spread of Japanese Knotweed is an offence under the Wildlife and Countryside Act 1981 and it is the responsibility of the landowner on which the plant grows to ensure it is managed safely.

Although it may take years to totally eradicate, there are a number of measures that can be taken to avoid the spread and damage to land and property that this plant can cause.

You can start by identifying whether you have Japanese Knotweed in your garden. In early spring red/purple shoots appear from the ground and grow rapidly forming canes. As the canes grow the leaves gradually unfurl and turn green.

The plants are fully grown by early summer and mature canes are hollow with a distinctive purple speckle and form dense stands up to three metres high. The plant flowers in late summer and produces clusters of spiky stems covered in tiny creamy-white flowers. Look out for the stem of the plant having a bamboo like appearance, the shovel shaped leaves and the fact it can grow by 10cm a day.

There are various approaches you can take to control the spread of Japanese Knotweed and primarily these involve spraying the plant with herbicide that contains glyphosate, such as Round Up, Tumbleweed and Tough Weed Gun. You can also cut the plant back and of course a combination of both can be even more effective.

It is however important that you do not mow or flail Japanese Knotweed as this could cause it to spread. Cutting with sharp hooks, slashers or hand pulling is recommended to avoid any dispersal. 

You should also avoid chipping Japanese Knotweed as mechanical chippers don't kill the plant and if you spread the chipped material on soil it could regrow.

The persistence of Japanese Knotweed rhizomes (underground stems) makes the plant hard to eradicate. Therefore be aware that you will need to treat Japanese Knotweed for a number of years, even though you may think you have killed it after the first treatment.

If Japanese Knotweed is regularly pulled up or cut the plant is weakened and over a number of years will begin to die off. A good way of disposing of the plant once pulled or cut is to thoroughly burn it on site in a controlled manner, such as in a metal bin.

While you can dispose of Japanese Knotweed by taking it to a deep landfill site by prior arrangement, it must be safely contained. A specialist contractor can also take it away for you, but do not take Japanese Knotweed material to your local recycling centre.

If you have large stands of Japanese Knotweed to treat you may wish to consult a qualified contractor. Licensed Japanese Knotweed sprayers must have a current National Proficiency Test Certificate.

Waltham Forest Council does not offer a service to deal with Japanese Knotweed but Council contractors, Urbaser, may offer a private, paid-for treatment service and can be contacted on 020 8520 9232. Charges for this service are payable directly to the contractor.

More information on Japanese Knotweed and other invasive plants can be found at or If Japanese Knotweed is growing on council land please contact Waltham Forest Council on 020 8496 3000.

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