Share This Post

Table of Contents

If you use Knotweed Services to treat your Knotweed infestation, we guarantee that these Invasive Plants will not grow back. Our warranty gives you extra piece of mind along with our 100% success record. We have worked for thousands of home owners throughout the UK and worked for some of the largest blue-chip brands in the UK and we have never failed.

Is Japanese Knotweed Regrowth Possible After Treatment?

Yes, it is indeed possible for Japanese knotweed plants to regrow after they’ve been treated. To completely remove Japanese knotweed, more than one pesticide application is necessary (or an excavation), and even the tiniest fragments of root left in the soil allows the plant to reappear and potentially cause damage to properties.

We typically advise two pesticide applications every season for three years, followed by two years of monitoring, to guarantee that all Japanese Knotweed has been effectively eradicated.

An insurance-backed guarantee and a 10-year warranty are available for this programme. We successfully eradicate Japanese knotweed with a 100% success rate.

If herbicide is used to kill Knotweed, can it grow back?

Certainly. Any expert on Japanese knotweed will tell you that it usually takes more than one application of a herbicide to kill this invasive non-native plant and make sure it won’t grow back.

Instead, it’s better to use the herbicide more than once (ideally between May and September, before the invasive weed enters the dormant stage of its growing cycle).

As we said at the beginning of this post, if you want to get rid of Japanese knotweed for good, you have to keep at it. To completely get rid of the plant, your Japanese knotweed contractor will have to come back to your property more than once. One dose of weedkiller won’t do the trick.

You could be better off forgoing herbicides altogether and excavating if you’re in a rush. Excavation is more expensive, but when time is limited, there’s no better treatment option.

Why can Japanese knotweed come back after being treated with herbicides?

Herbicide treatments like stem injections can take at least three years to work, and it can take even longer if Japanese knotweed has spread over a large area. Since it doesn’t spread by seeds but by a root system called a Japanese Knotweed rhizome, this perennial plant can keep growing underground even if it looks dead on the surface.

Knotweed can still be found even if professional treatment plans haven’t yet been completed or have been carried out hastily. If you disturb it by digging, planting, building a house, or any other means, it can grow back. 

Reasons That Japanese Knotweed Grows Back After Treatment and How to stop it

1. The Use of a Low-Cost Alternative

If you or your gardener just buys Roundup weed killer and uses it once, it might stop some of the knotweed from growing at first, but in the long run, it will still grow and come back the next spring.

Solutions, like doing it yourself to keep costs down, can work in the short term, but they are not a good way to get rid of the problem in the long term and you’re almost guaranteed to see it sprout again, plus if you’re trying to sell your house – you won’t have a Japanese Knotweed management plan and this can cause complications with a mortgage lender. You need a Japanese Knotweed Specialist.

2. You've cut the Knotweed stems down 

If you’ve tried to get rid of Japanese knotweed by cutting it off at the root, this won’t stop the plant from spreading.

Knotweed spreads by a tenacious root system that will continue to develop even if there is no plant above ground. There have been cases of knotweed roots growing through buildings, roads, and pedestrian walkways. It’s a plant with incredible strength and power, and one that should be respected as such.

3. You didn't correctly dispose of Knotweed Waste

Japanese knotweed is on a list of plants that are considered a controlled waste under the 1990 Environmental Protection Act. This means that a licensed waste carrier must get rid of it in the right way.

Remove and properly (and legally) dispose of Japanese knotweed to prevent it from coming back to take over.

After being treated, can Japanese knotweed become dormant?

By overdosing on glyphosate or applying residual herbicides, it is possible to make Japanese knotweed go dormant.

These techniques may be used by unqualified and unaccredited businesses to provide property owners who want the plant removed immediately with a short-term solution at a lower cost. 

Unfortunately, using these methods might have a negative impact on the environment and be short-lived on halting the problematic plant growth. A season or two after receiving such treatment, the plant begins to die back while the rhizome system recovers from the chemical onslaught underneath. The underground stems will emerge from hibernation and resume its previous growth patterns when the correct circumstances are present.

Professional, PCA-accredited Japanese Knotweed companies that stop the spread of knotweed utilise glyphosate treatments that are lawful and adhere to dosage and application guidelines. 

They will be upfront about how long it will take to get rid of the plant and won’t guarantee a quick treatment for an infestation (which can vary depending on the severity of the infestation). 

They won’t promise a quick treatment for an infestation and will be open and honest about how long it will take to get eliminate the weed (which can vary depending on the severity of the infestation). 

Japanese knotweed treatment schemes that have received PCA accreditation can take many years to complete since companies need to return to the site to reapply the chemicals after each growing season to make sure that the plant’s new growth is maintained to a minimal until it is completely eradicated. 

Trustworthy Japanese knotweed experts like Knotweed Services offer insurance-backed guarantees as a result, giving the property owner peace of mind that the infestation will be completely eradicated.

Does it still spread whilst dormant?

Although Japanese knotweed has a high rate of spread, it does not do so when it is dormant, either above ground or beneath. During its dormant period, the plant does not absorb any nutrients from above the ground, therefore it has no energy to spread. The plant could, however, unintentionally spread if the ground is disturbed. It is more likely that the plant will emerge from hibernation to grow and spread once more if rhizomes are disturbed by a gardener or large machinery.


If you don’t have any experience with Japanese Knotweed, then it’s best to leave it alone until you find a company who does.

If you are looking for a reputable company with years of experience dealing with Japanese Knotweed then look no further than our team here at Knotweed Services. We offer a free identification service and our site surveyors will visit your site to assess the situation and provide you with a detailed report outlining what we believe needs to be done.

This includes a full assessment of the current state of the knotweed infestation as well as recommendations for future action. If you decide to go ahead with us we will carry out all work required to remove the knotweed completely. 

We have a 100% track record!


Are your pictures on a different device? Don’t have pictures available at the moment? No problem! Sending pictures to us is EASY at ANYTIME. You can contact us via the following:

SMS Text






1 Step 1
Fill in the form below, attach your pictures and we'll let you know if the plant in your picture is Japanese Knotweed.

Please choose from one of the following:

By sending this form I consent to let Knotweed Services (UK) Ltd collect and store the personal data contained in the above form submission, so that they can respond to my enquiry. 

FormCraft - WordPress form builder

More To Explore

Table of Contents Introduction Knotweed Services is a company that provides education, awareness, and professional services relating to Japanese knotweed. Japanese knotweed …

Can I get a mortgage with Japanese Knotweed? Need to know how to get a mortgage with Japanese knotweed? Knotweed Services UK …

WHAT A SEASON!!!! CONGRATULATIONS MEADOW PARK! Knotweed Services could not be prouder of Meadow Park U11’s INCREDIBLE achievements this season and it …

We use cookies to give you the best online experience. We do not pass over any personal information to 3rd parties via our cookies. If you do not accept cookies, our website may not display or function correctly.

Privacy Settings saved!
Privacy Settings

When you visit any web site, it may store or retrieve information on your browser, mostly in the form of cookies. Control your personal Cookie Services here.

These cookies are necessary for the website to function and cannot be switched off in our systems.

In order to use this website we use the following technically required cookies
  • wordpress_test_cookie
  • fc_sb_1

Decline all Services
Accept all Services