What is Japanese Knotweed?
In the late 19th Century, the Victorians discovered this beautiful, fast-growing ornamental Japanese plant, and introduced it to the UK.
150 years on, its prolific nature – in the Summer months it can grow up to 10cm a week! – is causing huge problems and there is little in the UK that naturally stops it growing.
Its roots go up to seven metres and then new shoots appear. The roots also go very deep, which is why there is such concern about the plant’s effect on foundations.
How to tell if it’s Japanese Knotweed:
The stems look similar to bamboo.
Dead canes will snap.
The leaves come out of the stem alternately on each side, rather than in pairs.
The stems are often a bright red and green.
The roots snap like a carrot.
The roots have an orange circle in them.
Why can’t I just dig it out?
Unfortunately, digging out the roots generally spreads the problem, unless you are prepared to remove a lot of soil (up to a depth of 3 metres, and 7 metres from the original plant), where it can be guaranteed that the plant and its roots have been removed.
Or cut it down?
Cutting in the short term (this gives you about a week in high-season) removes all visible shoots and stems, but the roots simply produce more stems or grow up elsewhere in the garden –you’re not removing the problem, just moving it.
Many customers often report to us that they have been cutting it down year after year but every year it gets more prolific, springing up all over the place. Treating the Japanese Knotweed as soon as possible is the cheapest and most efficient method of removal.
Did you know?
Japanese Knotweed is such a problem in the UK that it is now illegal to knowingly transport or remove Japanese Knotweed. A plant just the size of a penny can grow quickly, so you can see why it’s such a problem.
Where has the knotweed in my back garden come from?
Most of our customers have no idea where the knotweed originated. Often it is transported unwittingly in builders’ waste, contaminated compost and from other such sources.
When it’s flowering, will the seeds grow into new shoots next year?
Most of the Japanese Knotweed in the UK is female (with the exception of a few sites) so pollination is not currently a problem. There is the potential for cross-fertilisation but currently the plants produced from this are nothing as fierce as Japanese Knotweed.
What is Common Ragwort?
Ragwort is usually found on waysides, grazing land and uncultivated ground and is seen from spring to autumn.
It poses a significant risk to animal health, with potentially fatal consequences if it is ingested by horses or livestock, either in its green or dried state.
It should be treated in late spring or autumn, however, cutting, wilting and treatment with herbicides make ragwort more palatable to livestock and poisoning mainly arises from eating contaminated hay.
What is Giant Hogweed?
Giant hogweed (Heracleum mantegazzianum) is a close relative of cow parsley originally from Southern Russia and Georgia. It can reach over 3m (10ft) in height. It is potentially invasive and the sap can cause severe skin burns.
It is widely distributed in the wild and poses a serious risk to people who are unaware of its potential for harm.
Because of the severity of the threat, Giant Hogweed is listed in the Wildlife and Countryside Act making it an offence to cause giant hogweed to grow in the wild in England and Wales. It can be the subject of Anti-Social Behaviour Orders where occupiers of giant hogweed infested ground can be required to remove the weed or face penalties.
Local Authorities have powers under certain circumstances to require giant hogweed to be removed.
Giant hogweed is a controlled waste (similar to Japanese knotweed) so if it is taken off site, can only be disposed of in licensed landfill sites with the required documentation.
The smaller, native hogweed, Heracleum sphondylium, is not classed as controlled waste but should still be disposed of with care to avoid human contact.
What is Himalayan balsam?
Himalayan balsam (Impatiens glandulifera) is a highly invasive annual, which has spread rapidly throughout the UK since its introduction in 1839. Native to the Himalayas, this vigorous growing annual has the ability to reduce biological diversity by out-competing native plants for space, light and resources.
Why is it a problem?
Growing mainly in damp woodlands and riverbanks, its prolific seed production coupled with a highly effective dispersal mechanism (seeds can be projected up to 4m) makes it spread quickly. Reaching heights of around 2½m, it often creates dense shadow, killing off native species. When it dies back in winter, especially on riverbanks, it can leave the area bare of supporting vegetation and therefore prone to erosion.
During the summer months it competes further with native plants as its high-sugar nectar and long flowering period attracts pollinators away from native species, reducing plant diversity in the area.
How can it be controlled?
Currently, chemical and manual controls are the only management options available for this species. Ideally, it needs to be dealt with before it sets seed. If control is undertaken early enough to prevent flowering (and if this is achieved before seed has set) then eradication is possible in two or three years. The plants, which are shallow-rooted, should be pulled out and disposed of by composting carefully, or by burning if seeds are present. If this is done on a regular basis and the plant is not allowed to set seed, it will eventually die out. Regular strimming of larger areas is also an option, as long as it is done often enough to prevent flowering.
This species is listed on Schedule 9 of the Wildlife and Countryside Act in England and Wales therefore, it is an offence to plant or otherwise cause to grow these species in the wild.