Japanese knotweed is not just an aesthetic nightmare but a legal one as well, here is everything you need to know about a rapidly spreading problem.

The Royal Horticultural Society has given some advice on how to deal with this type of infestation.

What is Japanese Knotweed?

This is a fast growing, clump-forming perennial, with tall, dense stems. They don’t just grow upwards they also bury themselves deep in the ground, which ultimately can affect the foundations of your house, making it difficult to sell.

Where does it come from?

It was originally brought to Europe from Japan by Phillipe von Siebold in 1829 and sold as an ornamental plant. It spread because bits would break off and it does not take much to start growing a new plant.

How can I spot it?

In Spring, reddish-purple shoots emerge from crimson-pink buds. These will grow rapidly in the Summer, producing dense strands of bamboo-like canes, which can grow to 7ft. The leaves are heart shaped.

Is it easy to get rid of?

Japanese knotweed is notoriously difficult to get rid of by hand and with chemicals.

How can Japanese knotweed affect the foundations of my garden and house?

Japanese knotweed buries itself deep into the foundations of your house and can grow from a tiny amount of the stem.

The legal issue with Japanese knotweed is that, if you are selling your house, it is your duty to get rid of the infestation or at least prove it is being managed by professionals. When selling, you must state whether you have Japanese knotweed anywhere on your property, even if it is a tiny amount. You must provide a plan of how it is being managed, without this it will slow down selling/buying.

New legislation in 2014 states that:

It is not illegal to have Japanese knotweed in your garden, but on your property you should aim to control this invasive non-native plant to prevent it becoming a problem in your neighbourhood. If it has a "detrimental effect of a persistent or continuing nature on the quality of life of those in the locality", the legislation could be used to enforce its control and property owners may be prosecuted.

When tackling Japanese knotweed, cultural control methods pose some problems.

Digging out this deeply penetrating plant without professional help, even if feasible, creates problems over disposal as Japanese knotweed is classed as 'controlled waste' under the Environmental Protection Act 1990. This requires disposal at licensed landfill sites.

Specialist Japanese knotweed contractors must be registered waste carriers to safely remove the weed from site but check first before employing their services.

On no account should Japanese knotweed be included with normal household waste or put out in green waste collection schemes.

Can I deal with it chemically myself?

It usually takes at least three to four seasons to eradicate Japanese knotweed using weedkiller.

Professional contractors, however, will have access to more powerful weedkiller that may reduce this period by half.

For home gardeners, perhaps the most effective and simplest method to tackle Japanese knotweed is with a glyphosate-based weedkiller such as Scotts Roundup Tree Stump & Rootkiller.

This has label recommendation for controlling Japanese knotweed, instructing it to be applied to the cut canes. SBM Job done Tough Weedkiller (soluble sachet only) also has label control for this weed.

Alternatively, try other tough formulations of glyphosate (e.g. Scotts Roundup Ultra, SBM Job done Tough Tree Stump Killer (soluble sachet only), Doff Maxi Strength Glyphosate Weedkiller or Westland Resolva Xtra Tough Concentrate).

Glyphosate-treated knotweed will often produce small-leaved, bushy regrowth 50-90cm (20in-3ft) in height the following spring. This is very different in appearance to the normal plant and it is essential that this regrowth is treated.

Bear in mind that the home gardener will not get an insurance backed guarantee without using a professional company for the control of Japanese knotweed. This may be important if planning to sell your property in the near future or if a neighbour is threatening litigation from the spread of knotweed from your property

Are there any good qualities to Japanese knotweed?

It is used in traditional Chinese medicine and traditional Japanese medicine to treat fungal infections, various skin inflammations, and cardiovascular diseases; one active ingredient is thought to be resveratrol and its glucoside piceid.

It is also used by beekeepers as it is an important source of nectar for the bees.

There are lots of professional knotweed extractors, you can look online to find the one that will suit you best. It is so important not to leave Japanese knotweed to its own devices.