The problem with the herbaceous knotweed plant is that a completely new weed can grow back from even the smallest of segments ? a section as small as your fingernail left in the ground is able to grow back fully. Cut stems can readily grow in lawns, soil or even in water. In spring, this plant will emerge and rapidly grow into a plant which is up to three metres high.
Small sections of this plant can be spread widely by soil transportation and also by small pieces being carried in waterways. This plant is such a problem in the UK that any soil removed from an area known to have knotweed present cannot be re-used and is supposed to be buried at a depth greater than five metres. The intentional spread of this plant is now illegal in the UK.
The cut plants can survive for up to three years, and are highly resistant to composting techniques. In fact, one of the worst things that can be done is to cut back your Japanese knotweed plant and then put it into the compost. When you come to use the compost on your garden, you can be sure that you will be fostering a great collection of new knotweed plants.
So, what can be done about japanese knotweed? Over an extended period of time you can repeatedly and harshly cut back and dig out the plant and its root system. Although it is difficult to remove all of the plant, over a number of years it is possible to weaken the plant so much that it becomes less of a problem. You must NOT compost the plant, and should not remove the cut sections to another site. Burning is the most effective way to remove the waste sections, where allowed. You must also ensure that rain water cannot wash away your cut sections or roots because this is seen as an intentional spreading of the weed.
Another method of control is to use a weed killer such as Roundup, which can begin the battle of removing this plant. However, even though this type of weed killer is very powerful, it may take many years to completely eradicate the Japanese knotweed from your garden. If you treat the plants more than once a year, such as at the start and middle of the summer, you will be more likely to remove the problem. Consulting a professional is a good idea, they will know the best course of action.
Do not mow or flail knotweed as the tiny fragments will create more plants. If you cut or remove a plant you must either burn it yourself or carefully remove it to a licenced point for destruction. Do not chip the remnants of your plant ? the chips themselves may grow back into new plants.
Acting quickly at the first sign of the Japanese knotweed is the best course of action. If you are harsh in your removal of the plant (disposing of it safely) then you can prevent the spread of this invasive plant. Don't forget that this plant is strong enough to cause structural damage to buildings. It can grow back from the smallest fragment and it is very aggressive in its growth. If in doubt at all, call in an expert company to treat and remove your knotweed.
As the Japanese knotweed spreads throughout the UK, along waterways, roadsides and on abandoned land, vigilance is required to make sure that it does not push out many of the weaker native plant forms. There are a number of sites on the Internet who make it their mission to remove this foreign invader. We must all do our part to remove this weed as much as is possible.
