Japanese Knotweed is a fast growing non-native plant that if left unchecked can consume your entire garden and in some extreme cases, even your house.

How can you identify Japanese Knotweed?

Japanese Knotweed looks different depending on the time of year, but one of its most easily identifiable features are the leaves.

The leaves are heart or spade shaped, with a curved point at the tip. They will generally stay the same shape but will change colour throughout the year.

In Spring the shoots appear and look like reddish asparagus stalks. When they appear, the leaves will start off light green.

In Summer, the stalks will grow and the leaves will darken. Summer is when the plant will grow the most and by the end of the season it can reach 2-3 metres tall.

In Autumn the plant will start to wilt and the leaves will become yellow and fall off. The stalks will become brown and hollow out.

In winter the surface plant will die off and will then lay dormant until the spring when its life cycle starts again.

Why is Japanese Knotweed a problem?

It’s such a problem, for landlords and homeowners especially, because without it being kept under control it spreads, and can take over a garden space suffocating everything in its path. It can even work its way into brickwork, causing serious structural damage over time.

This can complicate getting a mortgage as you may not be able to get one unless the house has been treated by a professional who can also give an insurance-backed guarantee.

How can you get rid of Japanese Knotweed?

There are a few ways that you can get rid of japanese Knotweed, but the tricky part is disposing of the remains as it is not normal household waste. It’s classed as controlled waste and therefore can only be disposed of by a licence holder.

Cultivation

First of all, the most obvious solution seems to be to just dig it all up. Unfortunately, because of the nature of the plant, this isn’t so easy. The roots of the knotweed can spread 3 metres deep and 7 metres wide, and if even the smallest part is left in the soil, it can regrow from that. This means if you don’t know what you’re doing and break up the roots in the ground, you could actually be multiplying your problem by creating new plants come next spring.

Spray

The second way you could get rid, is by using a chemical weedkiller. The plant will need to be treated multiple times, and may sprout back differently and more bushy looking.

Weed killer is to be used with caution as you run the risk of killing everything else in the garden and making the soil uninhabitable, so unless you know what you are doing, it’s recommended that you use a professional registered with PCA Invasive Weed Control Group. This group was formed by the RICS (Royal Institution of Chartered Surveyors) has worked with the PCA (Property Care Association)

The benefit of this is that the work will likely be insurance-backed, so should it pop up again in future, you are covered!

Disposal

Burn

You can burn anything you pull up, or dig out. But first you will need to check with your local council that burning is okay. You will then need to bury the remains.

Bury

To bury the remains you will need to wrap the remains in a weed protective barrier and then bury it at least 5 m down.

Professional Disposal

You can get in the professionals to remove and destroy the waste but it is your responsibility to check they are registered waste carriers.

Failure to follow the rules and regulations could result in a £5000 fine or a 2 year prison sentence.

For further information check out the Royal Horticultural Society’s website linked here.