I am actually working with my town on JKW, but while this is a long list, this is absolutely the only agreed scientific way to control it at this time. It tends towards dormancy when under attack, so you never know if after it disappears that it shoots up again in 10 years. It grows under cooled lava and waits - that aggressive.
- DO NOT MOW OR CLIP. Knotweed can grow from any intact node of the living canes as small as a thumbnail.
- Cutting or pulling the above ground growth down can cause the plant to grow aggressively underground, where the invasive rhizomes can shoot deep and wide, making your problem worse.
- Tarping or covering does NOT WORK - it will go quiet and grow around it; you also want a healthier plant to spray in the fall.
- The chemical to use is Glyphosate. To avoid any myths -- glyphosate itself is not the horrible chemical itself that causes cancers; The other additives (surfactants) in RoundUp can be, but you can use it if it's all you have. You need to use PPE.
- The knotweed cane is hollow on the inside; it will not help to put anything in the center; less likely to have the herbicide be effective
- The reason cutting and stem injection is often less effective is that nutrients are not pulled down via the inner hollow portion, but the cell wall. Foliar (leaf) and outer stem application pulls down when absorbed via this more effective process.
- Waiting to foliar spray after flowering and before frost allows the plant to use its effort above ground, then in the fall, it naturally tries to pull energy and nutrients into its rhizome (root) network for winter storage; this is generally good in late Sept or early Oct around here
- When we spray the leaves just after flowering, a healthier plant pulls all the chemicals underground through the leaves, which is what actually disrupts it. Only cutting will do nothing to stop it. Burning it does nothing. Pulling it makes it aggressive.
- If near water, there are some other chemical solutions so need to watch that
- The research is clear and I will have that compiled for my stuff, but mechanical removal will never work. There's no guarantee that it's gone forever with chemicals, it only controls it.
In order to use the plant’s processes against itself, having normal growth allows it to sink the herbicide application most efficiently through the foliar and stalk spray. After flowering, it is moving nutrients for the winter in order to go dormant and have food over winter. A weaker plant could go dormant and not efficiently sink the herbicide to the rhizomes. This delays progress or stimulates lateral growth underground (as it knows it’s being attacked). Applying to normal leaves lets us use its own process like a Trojan horse.
Here's the science for those interested: https://link.springer.com/article/10.1007/s10530-018-1684-5
So say I use glyphosate. When and where do I spray? There are maybe 7 plants total. I pulled all of them up by their roots (it looks like) including the one I took a photo of. Two snapped off at mulch level. I don’t see any other growths besides this extremely localized area. These were all about a foot tall two weeks ago before I pulled them then.
You spray in the fall season ONLY: after flowering but before your first frost. Do not spray before this or it won’t be as effective. They will grow back from wherever they are broken off in the ground at the rhizome and usually pretty quickly unless they were seedlings, which these don’t look like. Also, you should just know that this can be a multi-year process because of the longevity of this plant. It may also come back after the first year of application in a bonsai form. Google bonsai Japanese knotweed for examples. Let it grow and spray that in the next fall season again.
Spray the leaves in September/october. You will most likely have more grown back by then. I pulled mine all too before I learned to let them grow and spray the leaves in the fall - 3 summers in and they’re still popping up but definitely not as bad as the first year
This is correct and backs up all the research I've done on it. We have lots of knotweed around because it easily contaminates construction fill. You'll find it commonly by highway overpasses, onramps, and in odd spots here in CT.
We have actually had better control cutting and injecting. But it is very time consuming and doesn't make sense fir large stands.
For large stands, we do a summer cut back with a fall foliar spray. The summer cut back forces it to pull stored sugars from the root system for regrowth, and the glyphosate application after growth further reduces the energy being stored over winter. Usually about 3-5 years we have elimited large stands.
https://extension.psu.edu/japanese-knotweed
The hybrid cutting and then spraying worked well for me but you do have to be careful with the cutting to make sure stalks are bagged. I left my bags in the sun to bake.
Yep the mid-season cut and spray in the fall method can totally work. Good especially if it’s old knotweed that is too tall to spray safely. Otherwise it’s better to have more surface area to transmit down into the rhizome and just let it grow and spray once. But this can work as a variation, for sure! I’ve read the PSU stuff. Check out the link from above too, especially the conclusion:
“Though no control treatment delivered complete eradication of F. japonica within 3 years of the first treatment application, glyphosate applied at an appropriate dose, phenological stage (Fig. 1) and level of coverage (using foliar spray and stem injection application) was found to be the most effective control treatment. An immediate recommendation for stakeholders is to discontinue the use of other widely used herbicides for control of F. japonica (particularly synthetic auxins) and unnecessary physical control methods (cut and fill, summer cutting and excavation) that add equipment and labour costs and increase environmental impacts, without improving control compared to spraying alone.”
I have a terrible infestation in my backyard but it’s near a little bit of a water source. You make an exception in your comment about water so curious on what the chemical move is for me?
They do make glyphosate products specifically formulated for use near water, aquatic versions, e.g. [https://www.forestrydistributing.com/aquatic-glyphosate-herbicides](https://www.forestrydistributing.com/aquatic-glyphosate-herbicides) - I've heard when 10 feet or closer and anywhere with chance of overspray. As with all applications, you're looking to dilute to 2-3% gly or per label.
Edit: some also recommend milestone with the ai aminopyralid around water, but I have no experience.
Glyphosate is not the best chemical for it; It often will make the plant just go into root dormancy, then it will pop back up years later (still better than nothing). Please look into imazamox (I use clearcast), it works great for foliar spray and stem injections. Aminopyralid also seems very promising for Japanese knotweed.
Imazapyr is the best chemical for eradication, but has the most downsides (like killing any other plant in the vicinity, including mature trees). I would never recommend using imazapyr in any situation.
Here's the actually nuclear option, burn down the neighbors houses. Now you're the only one in the neighborhood. You now have the nicest lawn in the neighborhood.
That’s not the nuclear option. Pulling it just removes what you see. What’s left will grow back more vigorously. You need multiple applications of glyphosate.
Do not throw it in the yard waste bin. That will just spread it to your garden. Contact your town and ask how to handle invasive species like this. We have a special place to take the trash - and be sure to put it in garbage bags and have nothing fall of your car on the way there.
And you can be fine - soon you neighbours also may have knotweed
Maybe there was a miscommunication? My yard waste bin is a large plastic trash bin that gets picked up and dumped god knows where every Friday or when I put it out. Same company that removes my trash. Should I not put it in there?
The main recommendation I hear for Japanese knotweed is to solarize it in a black plastic garbage bag until it is really dead. This stuff is one of the worst invasive species on the list and solarizing it kills it so it can't keep growing wherever it is dumped.
Depends how it's made. Up here, Walker Industries has massive tarped concrete bunkers where bacteria superheat & kill everything. It's tightly controlled and you get no biological components.
However, if trucks are just dumping stuff into a pile that gets turned over now and then, it could be a different story.
There are certain invasive plants that should be put in a garbage bag and disposed of in the trash. That’s what I do with garlic mustard. I’m not sure about knotweed, but the stuff is pretty awful. It’s not a bad idea to keep it separate.
Be warned it'll grow right back out of the shoots you're throwing in there...I hate this frickin stuff so much. It is so terrible for the ecosystem. I pull mine constantly and after 5 years it's getting a little less intense. I use a little tool to stick down and lift up to get as much as I can out, then let it bake in the sun on my drive before throwing it in the trash.
It’s everywhere now where I live. Mainly along the roads on verges etc where people don’t treat or live.
They used to sell this as a decorative plant in Home Depot. Can you imagine..
Yea man, I had that around one of my friends houses, we cut it down . Sprayed it with straight round up concentrate, put plastic down and about 12 inches of mulch… a month later it was pushing the plastic and mulch in the air unless some areas it just pushed through the plastic
I bought this house in the winter (Michigan) and now that we have nice weather, my entire yard is about 50% weeds, 30% grass, and 10% dirt. I don’t even know where to start…
You only got 10% dirt? My yard was apparently a flagstone patio before I bought the house. The old owner pulled it up and put sod down, but they never removed the sand layer under the stones so 2 years later I've got mostly dirt with grass patches more scraggly than an incels beard.
We had knotweed. Let it grow all summer, don't cut it, don't dig it out or dig near it. At the end of August, early September spray the shit our of it with roundup. Repeat next year. Watch closely for new growth every year, it will try to come back.
Check your local laws on property sales infested with knotweed.
I'm not sure if you have the same or similar protections, but in the UK, not declaring or purposefully hiding a knotweed infestation prior to a sale can open you up to an expensive fight.
Properties with knotweed over here are priced lower than usual and still often take longer to sell due to how costly, in both time and money, knotweed can be to maintain.
You can deal with it for years and it could still come back if you stop the treatment once you think it's gone.
Japanese Knotwood: Nuke it from orbit...nasty stuff. Also, be careful if you remove it and transport it. It was introduced in my area to help with erosion prevention on the Erie canal. Invasive species
Eat it! It's delicious and it will help control the spread. I usually use it in anything that you add asparagus to, just keep in mind it's quite acidic. Makes great pickles too!
As someone who has a large patch, don’t dig it up or cut it down. The only thing that has been effective is stem injections at the end of the season in September/October. Then cut the husk once it’s fully dried out in Januaryish. We have done this method the last 3year and out patch has more than halved in that time.
Confirmed knot weed. I'm currently dealing with a massive invasion on my new property.
I'm told to let them flower, then spray glycophosphate this summer/fall.
Don't try to cut it or pull it. You'll just promote the roots to spread
That is for certain knot weed possibly even Japanese Knotweed. To kill it will take time and effort. Your options that are proven to work are:
1. Bury it under 10’ of soil.
2. Dig it up and be sure to get every little piece and bag it and get rid of it.
3. Get yourself a needle like used to inject chicken or meat when cooking. Get commercial grade glycophosate not just round up, but like concentrated round up which is much higher glycophosate than store bought. You can get it from DoMyOwn website. Let the shoots grow to about 6” or so and cut them so the hollow tube is left and go around with the needle and squirt about 1 tablespoon of the glycophosate down in each one.
It will take a couple years using option 3 but it does work to kill it all off. Then keep an eye for any stragglers and try to figure out the source (Ie nearby woods, creek beds etc where it may have spread from if it wasn’t a planted intentionally as a decorative.
I had the Japanese crap all over a hill in my back yard pretty much got it all gone with option 3. Option 1 and 2 were not in the finances or time.
Tried #3 and got hit with it in the face after injecting a few, learned really quickly to angle the injections downward. Did not seem to help so I am trying #2...
I may try to get a pro to do this as I feel like I keep losing ground.
Injections don't work from what I've found. You have to spray the foliage as it leafes out and then wait until it's dead to cut it. I'm on year 3 of trying to get rid of mine and this is the only thing that is working.
Professional landscaper who has dealt with this forever and it is truly diehard. One property that I tend to is next to the national guard compound and it grows to the fence in through the asphalt into the bank parking lot. A lot of weed trees grew up there as well mostly on the national guard side and one came down and took out an important cable to the bank. All hell broke loose in the following day the national guard without the with chainsaws and equipment on both sides of the fence and waged war on the weed trees and our little buddy knot weed. They sprayed the hell out of it, came back and sprayed the hell out of it again and let me say that That was 5 years ago and there are still fragments of that plant that attempt to come up every year. And I guarantee you the chemicals that they had it they're disposal were nasty. It is a tough plant.. It's under control now because they are on top of it whenever it shows it's leafiness up to two or three inches but the fact that it's still perseveres is amazing.
And this weekend I was a guest at a lovely New England estate that I once did a lot of work for, and as I strolled through the extensive gardens yesterday I noticed that the latest tenders are not vigilant and I saw baby not weed growing up in the peonies.. oh boy.. but other than inform me the owner I have no more skin in that game thankfully Now wonderfully retired I just get to go look at other people's work and smile
Yup it’s awful stuff. Glyphosate is the stuff to use. Probably what the army used too. The significant quantity of research pointed to Glyphosate as being the most effective chemical to permanently eradicate knot weed when used in proper concentrations at the proper application times. As you know, getting the roots and underground shoots to die is the only way to truly kill it off and not just have it come back weaker. Also really important to not let it go to seed.
In England, you can’t sell property anymore with Knot Weed on it! That’s how bad it is.
I just found this out recently, as well. Wasted time doing the injection method only to realize that spraying the leaves in the summer/fall AFTER they flower is the only way to kill it properly.
At least it doesn't have a waxy layer like ivy. So this makes it easier - just time consuming.
100%! I spray mine in the spring/summer just to keep them from getting big and healthy, but you def have to hit it when the energy is returning back to the roots.
It's all about timing. If you spray in the fall, after they've flowered, they're finally storing energy in their roots - before that, transport only goes from roots to shoots, not shoots to roots, so any weedkiller you use won't get to the roots where it's needed.
100%. I spray in the spring to keep them small and struggling and then spray through fall until they turn black. When I moved there were about 200 canes, roughly 12 feet tall, now I have about 50 that I don't let grow over 3ft. What a nightmare plant, honestly!
https://extension.psu.edu/japanese-knotweed
Was able to get rid of mine in just two seasons following this advice. Basically cut it all back end of May, beginning of June. Let it grow back and use up resources. Then later in August/September spray glyphosate (8 weeks after cutting) so it sucks it into the rhizomes. Should mostly die off after first season, but repeat for second season as necessary being watchful for regrowth. I waited another season before digging up as much of the dead rhizomes as possible.
This is so useful. This will be my third summer fighting them. I'll try the eight week method. But it'll be so frustrating watching them grow for 8 weeks.
Aminopyralid/Milestone is expensive but works better on knotweed than glyphosate. You just can't use it near vegetable crops especially legumes, locust trees, or on grazing land. That said, knotweed is a serious enough problem to warrant it
Don't dig it up, trust me. You won't be able to get the full rhizome and by digging it up it will cause it to spread and create more. You'll have dozens in just a couple months.
Lord, I’m getting so many different opinions here. What do you think I should do? I’m not saying any one person is wrong, I’m just going to wake up tomorrow and see what the general consensus is, because frankly, I don’t know anything about this.
They are right that you won’t get the full rhizome but if you get 80% then it will sprout again and you get 80% of it the next time and eventually the season will be over and what’s left will rot over winter. I’ve had success doing it but only on a small patch
Sell the house. That’s what I did. I did actually move but not just because of the knotweed. I dug it up before figuring out what it was. It made it angry and sent runners underground everywhere. If you are going to try and dig it out, destroy everything. Remove the soil completely in whatever way is legal or morally not reprehensible for you and replace with new soil. Otherwise go the round up approach. Or both. I tried injecting, cutting off in the fall and injecting stalks, spraying the foliage and waiting for it to die and then cutting. Knocked it back a fair amount. Then put blue tarp over the whole area and couple inches of mulch and some raised garden beds. Still had some shoots find a hole in the tarp a few times a year and had to spray and then remove some runners around the edges. After a few years it got manageable. Then I moved. Not sure how the new owners have fared. Honestly, Best of luck. On the plus side it actually particularily ugly and not poisonous.
I know someone who does that with bamboo, do you have to worry about the chemical causing collateral damage to any plants that have been invaded by the knotweed?
I got sick to my stomach just seeing the picture. I have it here in New York. The first summer I cut and sprayed with round up every weekend, that only seemed to encourage it to spread outward.
Last year I read to leave it be until fall, spray it after flowering but before frost. It killed me to just let it sit all summer. I see some sprouting so far this year. Hoping I made at least some progress.
Good luck!!
This. I did this. Still seeing random sprouts but I also can’t get 100% sprayed because it’s down a ditch and coming from upstream the creek at the bottom of said ditch. So I constantly monitor for sprouts and get them sprayed young. Use the 360 roundup for extra protection.
Use milorganite to get your lawn to grow. (Everything will though) super cheap and amazing. Your lawn will smell like a deuce for a day or two after though.
Spend this year cutting out weeds.
Seed in late fall. Cover with peat. (Thatch first if you are going to overseed)
Next year will have a super green full lawn.
Just spent the better part of yesterday cutting all over 1ft. I plan to hit the patch weekly as this is year 5 of my war which I am not winning. Last few years I've gone with poison which just killed it all but the knotweed came back quickly.
If I can't gain ground this year I'm calling in a pro, this shit is crazy!
Sounds like I’m lucky that I’m limited to just a few square feet of it, that I can tell. Only spot seems to be right outside my spare bedroom window. Probably just gonna dig the fuck out of that area and hope for the best.
Dig it up and make sure nothing is left. Don't leave pieces, clean it all up as some can grow into a few plant.
Just a few feet should not be hard to remove but like others said be sure to dispose of it properly, check with your town. Sounds like you can beat this with a few hours of work, well worth doing it now before a 4 feet become 8 and then some. Good luck!
No, don't cut i! You need to let it leaf out and spray with concentrate BioAdvanced Brush Killer once per week and then only cut it down when it's fully dead. Cutting it or digging it causes the plant to react by accelerating its growth rate under ground and will cause new shoots to sprout quickly.
https://extension.psu.edu/japanese-knotweed
As I wrote in another comment, you have to wait to spray after cutting. If you spray early it only kills foliage not the root system.
Sorry to hear you have this. FYI In the UK you are required by law to declare this when selling a house. It has to be declare even if it has been treated.
US here. Every house comes with a fifth of Bourbon and a shotgun. Honestly, I’m not sure about the laws here, but I had two inspections done, one from my lender and one from my own pocket, and not a thing was said about the yard.
😂 I had to Google the horror. I read horticultural vinegar down the spinal cavity is a pretty solid. If it were me I’d do that or gasoline. No way it lives through napalm.
Oh no!!!! I'm on year 3 of trying to get rid of mine. Use BioAdvanced concentrate and spray it as it leaves out. Don't cut them down until they're dead, it will make them grow faster.
Can I ask where you're located?
I'm zone 5b (northern IL) and we recently went through this. I had friends who were literally having nightmares about the knotweed in our yard!!
Knotweed Excavation https://imgur.com/gallery/t8pu9KT
When we first bought the house, we replaced and installed a fence for our dog, where the fence guys chopped down anything nearby, including the knotweed. When we had someone from a plant nursery come identify things in our yard for us, he called the cut bulbs "old growth peonies". I was watering the damn things until I was video calling with my mom and she said "those aren't peonies" (oh, how much I've learned since then!)
Anyways - 3 years later and the method we've used was mostly successful. That first year, we let it grow and expend a ton of energy putting up shoots. Then we hired someone to pull it all up. If you let it sit out and die (or get sent for compost heat treatment) it's fine. But any bit leftover will try to grow again - if it has the energy.
Our trick since has been to dig the root out as deep as possible, as early as possible so it doesn't get any energy.
However, the only effective time to use herbicides is the fall, after they've flowered, when they're finally trying to store energy instead of use it. I never wait for them to flower before I pull them up, but if I see anything in the fall I do spray it.
My extension office and city have been of no help in eradicating this. It has spread to all 5 neighboring lots, but due to our treatment plan, I only get a handful still popping up.
Happy to talk details if you need it! You're going to want to control these as best as possible tho, as knotweed roots have been known to crack concrete (I'm concerned that there's siding at the back of your photo...)
As you’ve seen in the comments, knotweed brings out the crazy in some folks. There’s a knotweed support group on Facebook that can be really helpful for guidance, but the group is closed for the season. It will open back up for new members in the winter.
What I did: No cutting at all. No burning. No digging. In the fall, once it has flowered but before the first frost, spray the plants thoroughly with a glyphosate mixture at a rate of 3-4%. (You may need to spray it while flowers are still on depending on when your frost is.) At this time of the year, the plant is sending energy down into the deep tap root, and the low dosage glyphosate will slowly take the chemical into the taproot, killing it over a few weeks. A high-mixture percentage of glyphosate will burn the leaves and not harm the tap root. It’ll send out new roots during the winter, and you will find new shoots the following spring. Glyphosate treatment any other time of year will burn and kill the plant you see, but the deep roots will still live, and they will grow out and send up more shoots in a different area. (The same thing happens if you burn or dig it.)
I followed this plan that was recommended to me last fall, and was 95% successful.
This is a helpful resource:
https://www.nwcb.wa.gov/images/weeds/Knotweed-Control_Whatcom.pdf
Almost wondering if this is from the piss poor mulch job that someone tried to do. The weeds seem a lot more concentrated within the mulch along my patio.
I’m pretty sure this is how I got it, I similarly have only a couple small patches in the mulched areas right next to my house. I think it gets cut down and sent off with yard waste to get mulched, then establishes itself at its new home when the mulch gets used 😭
Every time a new stalk pops out I’ve just been digging down as far as I can, cutting it, and applying 50% glyphosate straight away to the cut stem. I’m hesitant to let it leaf out and leave it all summer like the advice you’re getting here because I want to starve it out - it can’t expend resources to spread underground forever if it never gets sun. Since it’s only a small amount I just watch it like a hawk all summer and cut the new stalks immediately as they emerge. So far this year I’ve seen much less of it than last year, and hasn’t spread to any new areas yet…
I had this in the backyard of my NYC apartment. Could not get rid of it. This is going to be a lot of work to dig up all the underground roots and burn. This stuff is relentless.
If herbicides are ok, just hire a chemical weed control professional. I killed a lot of this for USACE and private landowners using aminopyralid. It won't happen in one treatment but it can be done.
Been battling this in my backyard since I bought my house five years ago..there’s a Japanese knot wood support group on Facebook you might want to check out; it has tons of good information. ETA: I just read through the comments on this thread and a lot of the suggestions and information given are inaccurate and ineffective, and could potentially make things worse for you. Japanese knotweed can grow through volcano lava, so most methods of removal just don’t work.
Depending on the size it will need stem injection with glyphosate to destroy it. This is at certain times of the year and has to be done more than once. Specialist company needed to do it properly. Waste needs to be disposed of properly and depending where you are there could be laws governing how it is to be disposed of.
Look up the facebook group Nixtheknotweed for a guide to killing it simply by cutting it to the ground with proper timing 3x per warm season for 3 years. Ignore the people saying it’s impossible to kill, you just need persistence and knowledge. It seems impossible if you’re ignorant of the plant and try to tackle it blind. Every time someone posts a photo of knotweed on the internet a bunch of dummies give their 101 impossibly laborious ways to wage war stated as fact. That’s not the advice you want to follow.
If you’re in Delaware I recommend contacting the Delaware department of agriculture for guidance. I thought we had Japanese Knotweed in our yard after seeing this post and they were very responsive, helped me accurately identify the weeds in question and gave me guidance on what to do.
They said for Japanese Knot Weed, if it’s a new growth you can dig it out, then if it’s still a problem come late spring/summer spray it.
https://delaware.gov/contact/
Japanese knotweed. Dig down 3' and 3' around but do so like an archeologist. Follow the rhizomes. They'll break off into tiny pieces if you cough or sneeze and each will reproduce an entire new plant. Dig it all up and find what direction it's running, it likely is elsewhere if you see one. The bigger and thicker, the more likely there's tons of rhizomes. I have mine mostly under control it's been a few years but I pluck starters every summer
Japanese knotweed. Inject roundup into the stem with a syringe. Digging it encourages spread of the roots. I had hundreds of these bastards in my yard when I bought my home. I managed to kill it all off after two years.
2oz crossbow 2oz roundup mix with water in a 0ne quart water spray bottle. Spritz to wet not run off. Treat at first signs and continue to treat new growth that shows up.
Your story is so similar to mine. Bought a house and discovered this on my property the first spring/summer. We have garlic mustard too (it’s even worse if you can believe it) on the other side of our fence that borders a green belt. The state and county I’m in has a noxious weed department - they have been coming out every year to spray the knotweed and garlic mustard free of charge (well, taxpayer funded ha). Going into year 3 and the knotweed is almost all gone, and the garlic mustard starting to turn. See if your county has something similar!
Edit: I tried mechanically pulling at first too, and it did fuck all. The root system gets super deep and wide spread and it’s almost impossible to dig out perfectly without fragmenting. I wouldn’t even try tbh.
Don’t touch it until you join the Facebook Japanese knotweed support group and do research on it. If you handle it wrong you will make the problem worse.
We tackled a ~20ft X 20ft plot of this a few years ago. First we tried cutting it, then pulling it, then I literally torched it, then we tried this stuff called RM43, total vegetation killer...It mostly worked, we still get a couple shoots every year but they are easier to pick/manage. I've heard using something like RM43 and then laying black plastic for about 5 years is supposed to get rid of it if you want to do the long slow game.
There’s another way. Make a fermented fertilizer with all your yard clippings and use it to fertilize a competitive but useful species e.g. mint or marigolds or nasturtium. More knotweed = more fertilizer.
[link to fertilizer](https://youtu.be/6izQfXMO9nY?si=ubBLEooJ6UDLEnTR)
Japanese knotweed. Welcome to my nightmare. Best bet is repeated glyphosate but honestly you might have to wait until fall for it to make it down to the roots. The rhizomes are everywhere and the tiniest bit will start growing a new plant. Sorry
How big is the area? If budget is low everytime a small sprout come up dig beside is and get it from the deepest point. Add weed killer down there. Try to take it out in one piece and place itnin bin. Small pieces of root system can regrow.
You can opt for getting concentrated glysophate and stem injecting it and just keep doing that until they are all gone. Wait til the olant fully dies before removing it. May even was to torch after pull to ensure any rhizomes on the surface die.
Well if you're alone is covered in that, you have to immediately have an exorcism. You're screwed.. Japanese knot weed once established is very difficult to eradicate. If the area is not really large, I would consider it covering it with plastic for a year lol It's that serious. You can spray it and it is possible to get rid of it but it is truly difficult. You simply can't dig it out even a tiniest little bit of plant will regenerate itself and only thank you for spreading it around and helping cultivate the soil.
You can mow it and to mow it and to mow it and it will not go away. Persistent and the minute you stop oh boy up it comes..
I just pulled mine and planted other stuff that was local. Seems it was out competed. Still get one or two a summer, but I'd say it's mostly gone
Reading the other comments it appears I did exactly the wrong thing. Seems to have worked tho
Looks like bamboo. Similar to knot weed both vary invasive . Sad to say. But may have to treat area with heavy brush killer. It will kill your grass as well. You can try digging but the grow by spreading out under ground like rysome similar to ground ivy and mint.
Once killed you can replant with grass seed.
If you wait until it goes to flower it’s at its weakest. Use a mix of Glyphosate and Crossbow. Anything short of killing it causes it to go in a defensive mode and puts all its energy into the roots.
There is a Facebook support group for Knot Weed, join it and the community notes and members can help you in your journey to remove it. I'm on year two, not a lot left, previous owner did a chip dump and creates knot weed patches all over my yard.
I once purchased a beautiful variagated variety of it that looked gorgeous in the garden and claimed it was slow growing and not invasive. I had it about 3 years before I moved. Wonder how it's doing now.
If you can remove all the root ball cluster junk underneath. Then you may be able yo get rid of it. You just have to get ALL of it. Though. It’s entirely possible the ‘infection’ is too far gone. Good luck~
My pain and anguish can actually have purpose. If this is your owned home and/or you’re in this house for the long term you have some options. None of them are great.
I had this at a rental property and I gave myself tendinitis pulling this crap up.
You need to dig until you can find the main root system. Let me tell you if probably monstrous and the roots could be as thick as a carrot. I can send photos of what we dug up.
Your goal is to unearth some big roots and chop an end off so you can submerge them in 5 gal buckets of salt water. Like 50/50 salt water. They will drink that water and it is the ONLY WAY to actually get to the whole root system. It will take months or doing this maybe even a year. Then you just continuously mow or cut down anything above the surface.
But even if you tried like I did to pull it all out, you can never get it all. I had price growing from a 1/2inch piece of root that got left behind. I tried roto-tilling and that just spread it. You can’t cover it up it will find a way through.
If you can figure out where it’s from and out in a physical barrier that could help slow the spread but it goes so deep it’s still a tricky thing.
Please ask any questions you have. It would make that whole ordeal so much better if I can help someone else.
Japanese Knotweed. I’m currently trying to rid of an established hedge 100 feet long of this crap. Thanks for everyone else sharing their tips! This stuff is HORRENDOUS!
I managed to get rid of knotweed on a big section of my lawn without using chemicals by just mowing weekly during the growing season for... 5ish years. It's now contained to the woods between properties and doesn't sprout up through the grass anymore.
Demon plant some a-hole landscape designer brought here Japan. Only thing I’ve seen beat it is smithing it in grass clippings. Honestly, I’ve tried everything from burning to chemicals. We had this wood line that this grew from it would invade into the grass one summer I just started burying it in grass clippings and I started gaining on it.
I have had success with mowing and carefully disposing of the clippings, and spraying with glyphosate in the fall after flowering. I also have dug out the crowns. If you keep on top of it and especially spray in the fall, you’ll get rid of them. I think your case of them isn’t nearly as bad as mine, as I had a lot of land filled with established ones.
I read so many things online and I have not had any issues with spreading by mowing, but the issue I think is people may be careless with mowing and spread it elsewhere. Trust me, you don’t want to have to look at this plant growing all over your neighborhood, it’s very ugly. It’s super common where I live.
If you don’t have many of them, you could also try digging it and throwing it away in the trash. Just dig the spot it’s in. They say if you break a root/rhyzome that it will just spread more, but I had success with this. I’ve been at it for 2 years now and I would say I am at 50% reduction of a very heavy infestation. Best attack is the glyphosate in the fall and keeping them from growing full size, and digging out any large crowns. I did glyphosate in the fall last year and that stunted a patch tremendously. You just spray the leaves with it. It will kill the grass around it but it’s worth it.
I read somewhere that battling knotweed will need to become your new hobby. I think you’ll be ok, but you have to get started asap.
I am sorry. My neighbors have been dealing with it for years. I think this plant is Satan. Do you have anyone you particularly hate you know might buy this property from you? Have you thought about the witness protection program? If it learns where you move, there is a good chance it will follow you... Again, I am sorry.
Knotweed.
I’m in the northeast and have dealt with it before. Let it grew until about June and then cut it down. In mid-August/early September you spray the plant with glyphosate.
You need to cut it down in June otherwise the plant will be 10ft tall by the end of the growing season making it difficult to spray.
I am actually working with my town on JKW, but while this is a long list, this is absolutely the only agreed scientific way to control it at this time. It tends towards dormancy when under attack, so you never know if after it disappears that it shoots up again in 10 years. It grows under cooled lava and waits - that aggressive. - DO NOT MOW OR CLIP. Knotweed can grow from any intact node of the living canes as small as a thumbnail. - Cutting or pulling the above ground growth down can cause the plant to grow aggressively underground, where the invasive rhizomes can shoot deep and wide, making your problem worse. - Tarping or covering does NOT WORK - it will go quiet and grow around it; you also want a healthier plant to spray in the fall. - The chemical to use is Glyphosate. To avoid any myths -- glyphosate itself is not the horrible chemical itself that causes cancers; The other additives (surfactants) in RoundUp can be, but you can use it if it's all you have. You need to use PPE. - The knotweed cane is hollow on the inside; it will not help to put anything in the center; less likely to have the herbicide be effective - The reason cutting and stem injection is often less effective is that nutrients are not pulled down via the inner hollow portion, but the cell wall. Foliar (leaf) and outer stem application pulls down when absorbed via this more effective process. - Waiting to foliar spray after flowering and before frost allows the plant to use its effort above ground, then in the fall, it naturally tries to pull energy and nutrients into its rhizome (root) network for winter storage; this is generally good in late Sept or early Oct around here - When we spray the leaves just after flowering, a healthier plant pulls all the chemicals underground through the leaves, which is what actually disrupts it. Only cutting will do nothing to stop it. Burning it does nothing. Pulling it makes it aggressive. - If near water, there are some other chemical solutions so need to watch that - The research is clear and I will have that compiled for my stuff, but mechanical removal will never work. There's no guarantee that it's gone forever with chemicals, it only controls it. In order to use the plant’s processes against itself, having normal growth allows it to sink the herbicide application most efficiently through the foliar and stalk spray. After flowering, it is moving nutrients for the winter in order to go dormant and have food over winter. A weaker plant could go dormant and not efficiently sink the herbicide to the rhizomes. This delays progress or stimulates lateral growth underground (as it knows it’s being attacked). Applying to normal leaves lets us use its own process like a Trojan horse. Here's the science for those interested: https://link.springer.com/article/10.1007/s10530-018-1684-5
Wow. Great post! I admitted defeat and moved (see previous comment) but this is a great summary I wish I had at the beginning of my battle.
So say I use glyphosate. When and where do I spray? There are maybe 7 plants total. I pulled all of them up by their roots (it looks like) including the one I took a photo of. Two snapped off at mulch level. I don’t see any other growths besides this extremely localized area. These were all about a foot tall two weeks ago before I pulled them then.
You spray in the fall season ONLY: after flowering but before your first frost. Do not spray before this or it won’t be as effective. They will grow back from wherever they are broken off in the ground at the rhizome and usually pretty quickly unless they were seedlings, which these don’t look like. Also, you should just know that this can be a multi-year process because of the longevity of this plant. It may also come back after the first year of application in a bonsai form. Google bonsai Japanese knotweed for examples. Let it grow and spray that in the next fall season again.
Spray the leaves in September/october. You will most likely have more grown back by then. I pulled mine all too before I learned to let them grow and spray the leaves in the fall - 3 summers in and they’re still popping up but definitely not as bad as the first year
This is amazing info, thank you so much for taking the time to share.
This is correct and backs up all the research I've done on it. We have lots of knotweed around because it easily contaminates construction fill. You'll find it commonly by highway overpasses, onramps, and in odd spots here in CT.
We have actually had better control cutting and injecting. But it is very time consuming and doesn't make sense fir large stands. For large stands, we do a summer cut back with a fall foliar spray. The summer cut back forces it to pull stored sugars from the root system for regrowth, and the glyphosate application after growth further reduces the energy being stored over winter. Usually about 3-5 years we have elimited large stands.
https://extension.psu.edu/japanese-knotweed The hybrid cutting and then spraying worked well for me but you do have to be careful with the cutting to make sure stalks are bagged. I left my bags in the sun to bake.
Yep the mid-season cut and spray in the fall method can totally work. Good especially if it’s old knotweed that is too tall to spray safely. Otherwise it’s better to have more surface area to transmit down into the rhizome and just let it grow and spray once. But this can work as a variation, for sure! I’ve read the PSU stuff. Check out the link from above too, especially the conclusion: “Though no control treatment delivered complete eradication of F. japonica within 3 years of the first treatment application, glyphosate applied at an appropriate dose, phenological stage (Fig. 1) and level of coverage (using foliar spray and stem injection application) was found to be the most effective control treatment. An immediate recommendation for stakeholders is to discontinue the use of other widely used herbicides for control of F. japonica (particularly synthetic auxins) and unnecessary physical control methods (cut and fill, summer cutting and excavation) that add equipment and labour costs and increase environmental impacts, without improving control compared to spraying alone.”
I have a terrible infestation in my backyard but it’s near a little bit of a water source. You make an exception in your comment about water so curious on what the chemical move is for me?
They do make glyphosate products specifically formulated for use near water, aquatic versions, e.g. [https://www.forestrydistributing.com/aquatic-glyphosate-herbicides](https://www.forestrydistributing.com/aquatic-glyphosate-herbicides) - I've heard when 10 feet or closer and anywhere with chance of overspray. As with all applications, you're looking to dilute to 2-3% gly or per label. Edit: some also recommend milestone with the ai aminopyralid around water, but I have no experience.
This person kills weeds \^
Glyphosate is not the best chemical for it; It often will make the plant just go into root dormancy, then it will pop back up years later (still better than nothing). Please look into imazamox (I use clearcast), it works great for foliar spray and stem injections. Aminopyralid also seems very promising for Japanese knotweed. Imazapyr is the best chemical for eradication, but has the most downsides (like killing any other plant in the vicinity, including mature trees). I would never recommend using imazapyr in any situation.
Looks like knot weed…..
Just did some quick research. Fuck.
If you pull it and throw it in the woods…. It will just invade that too..
I have a yard waste bin that I’ve been pulling and throwing into. No woods here, it’s a suburb. Everyone’s lawn is so nice except mine lol.
you know what to do..
Loading my shotgun up as we speak.
maybe a little more bad neighbor, and a little less Satan
Lmao BUT MAH RIGHTS
you know what - do you, what's the worst that can go wrong?
Felonies, loss of gun ownership rights, job loss, exorbitant fines, property loss. Other than that, not much.
You have every reason to live!
Lmao evillllll…. Also I will now be going around sharing the morning glory!
Pull em and toss around neighbors lawn so eventually they all look like yours.
The nuclear option. I like it. Can’t have a bad lawn if everyone’s is bad!
Here's the actually nuclear option, burn down the neighbors houses. Now you're the only one in the neighborhood. You now have the nicest lawn in the neighborhood.
But also the worst one
That’s not the nuclear option. Pulling it just removes what you see. What’s left will grow back more vigorously. You need multiple applications of glyphosate.
I agree, pulling it out will leave to root in pieces to grow. Use a paintbrush to apply to the stem after you cut off. Repeat as necessary.
I recommend getting a fire pit and disposing of it that way.
Do not throw it in the yard waste bin. That will just spread it to your garden. Contact your town and ask how to handle invasive species like this. We have a special place to take the trash - and be sure to put it in garbage bags and have nothing fall of your car on the way there. And you can be fine - soon you neighbours also may have knotweed
Maybe there was a miscommunication? My yard waste bin is a large plastic trash bin that gets picked up and dumped god knows where every Friday or when I put it out. Same company that removes my trash. Should I not put it in there?
The main recommendation I hear for Japanese knotweed is to solarize it in a black plastic garbage bag until it is really dead. This stuff is one of the worst invasive species on the list and solarizing it kills it so it can't keep growing wherever it is dumped.
You're fine. It gets recycled into compost and sold back to you.
Pretty sure knotweed needs to be disposed of properly so as to not infect this “compost that gets sold back to you”
Depends how it's made. Up here, Walker Industries has massive tarped concrete bunkers where bacteria superheat & kill everything. It's tightly controlled and you get no biological components. However, if trucks are just dumping stuff into a pile that gets turned over now and then, it could be a different story.
This is why you have to contact the city to find out how best to dispose of invasive plants from the yard.
I found a nerf gun pellet in my municipal compost, along with shards of glass and bits of plastic sooooo….
Okay, that’s more or less what I figured.
There are certain invasive plants that should be put in a garbage bag and disposed of in the trash. That’s what I do with garlic mustard. I’m not sure about knotweed, but the stuff is pretty awful. It’s not a bad idea to keep it separate.
Be warned it'll grow right back out of the shoots you're throwing in there...I hate this frickin stuff so much. It is so terrible for the ecosystem. I pull mine constantly and after 5 years it's getting a little less intense. I use a little tool to stick down and lift up to get as much as I can out, then let it bake in the sun on my drive before throwing it in the trash.
Do not throw it with yard waste. It needs to be bagged up, thrown in the trash, and sent to a landfill (or you can burn it).
Throw it in theirs. Problem solved!
Shit, I’m worried enough about dandelions blowing their seeds into my neighbors lawn.
Burn it!! If that doesn't work move! I've been fighting a patch for 24 years now and I still get the occasional stem rearing it's ugly head.
It’s everywhere now where I live. Mainly along the roads on verges etc where people don’t treat or live. They used to sell this as a decorative plant in Home Depot. Can you imagine..
I watch mine burn in the fire pit.
Yea man, I had that around one of my friends houses, we cut it down . Sprayed it with straight round up concentrate, put plastic down and about 12 inches of mulch… a month later it was pushing the plastic and mulch in the air unless some areas it just pushed through the plastic
I bought this house in the winter (Michigan) and now that we have nice weather, my entire yard is about 50% weeds, 30% grass, and 10% dirt. I don’t even know where to start…
Yea this shit is no joke
You only got 10% dirt? My yard was apparently a flagstone patio before I bought the house. The old owner pulled it up and put sod down, but they never removed the sand layer under the stones so 2 years later I've got mostly dirt with grass patches more scraggly than an incels beard.
We had knotweed. Let it grow all summer, don't cut it, don't dig it out or dig near it. At the end of August, early September spray the shit our of it with roundup. Repeat next year. Watch closely for new growth every year, it will try to come back.
Fertilome Weed Free Zone works well. Prepare the site and plan to overseed in early fall.
Check your local laws on property sales infested with knotweed. I'm not sure if you have the same or similar protections, but in the UK, not declaring or purposefully hiding a knotweed infestation prior to a sale can open you up to an expensive fight. Properties with knotweed over here are priced lower than usual and still often take longer to sell due to how costly, in both time and money, knotweed can be to maintain. You can deal with it for years and it could still come back if you stop the treatment once you think it's gone.
Japanese Knotwood: Nuke it from orbit...nasty stuff. Also, be careful if you remove it and transport it. It was introduced in my area to help with erosion prevention on the Erie canal. Invasive species
Why would they do this. This is probably the stupidest thing to do.
Just start looking for another house while you can still sell that one.
Too late, I already burned it down.
Join us newcomer. We, the knotweed plagued. Look around you, just look around you and see the glorious knotweed. All over. All encompassing.
I cut them down and am using a vacuum to force feed them Marlboros. Sometimes ya gotta think outside the box.
It is Japanese.... Wait till fall- cut it down to 6 inches and pour round up into the stocks...
you can cut it up and sauté it, it has a citrusy hit to it
Eat it! It's delicious and it will help control the spread. I usually use it in anything that you add asparagus to, just keep in mind it's quite acidic. Makes great pickles too!
As someone who has a large patch, don’t dig it up or cut it down. The only thing that has been effective is stem injections at the end of the season in September/October. Then cut the husk once it’s fully dried out in Januaryish. We have done this method the last 3year and out patch has more than halved in that time.
Confirmed knot weed. I'm currently dealing with a massive invasion on my new property. I'm told to let them flower, then spray glycophosphate this summer/fall. Don't try to cut it or pull it. You'll just promote the roots to spread
Yup camper here to say that any little breakage can spread herbicide is the only way to properly kill it
That’s what I say when the cop ask what’s in my pipe.
Yep, Japanese knotweed
I was going to say early this
Nah, that's not weed
That is for certain knot weed possibly even Japanese Knotweed. To kill it will take time and effort. Your options that are proven to work are: 1. Bury it under 10’ of soil. 2. Dig it up and be sure to get every little piece and bag it and get rid of it. 3. Get yourself a needle like used to inject chicken or meat when cooking. Get commercial grade glycophosate not just round up, but like concentrated round up which is much higher glycophosate than store bought. You can get it from DoMyOwn website. Let the shoots grow to about 6” or so and cut them so the hollow tube is left and go around with the needle and squirt about 1 tablespoon of the glycophosate down in each one. It will take a couple years using option 3 but it does work to kill it all off. Then keep an eye for any stragglers and try to figure out the source (Ie nearby woods, creek beds etc where it may have spread from if it wasn’t a planted intentionally as a decorative. I had the Japanese crap all over a hill in my back yard pretty much got it all gone with option 3. Option 1 and 2 were not in the finances or time.
Tried #3 and got hit with it in the face after injecting a few, learned really quickly to angle the injections downward. Did not seem to help so I am trying #2... I may try to get a pro to do this as I feel like I keep losing ground.
Injections don't work from what I've found. You have to spray the foliage as it leafes out and then wait until it's dead to cut it. I'm on year 3 of trying to get rid of mine and this is the only thing that is working.
Yup. I successfully got rid of a patch in my yard. Took 3 years of spraying twice a year, summer and fall. This is the first year it didn’t come back.
Professional landscaper who has dealt with this forever and it is truly diehard. One property that I tend to is next to the national guard compound and it grows to the fence in through the asphalt into the bank parking lot. A lot of weed trees grew up there as well mostly on the national guard side and one came down and took out an important cable to the bank. All hell broke loose in the following day the national guard without the with chainsaws and equipment on both sides of the fence and waged war on the weed trees and our little buddy knot weed. They sprayed the hell out of it, came back and sprayed the hell out of it again and let me say that That was 5 years ago and there are still fragments of that plant that attempt to come up every year. And I guarantee you the chemicals that they had it they're disposal were nasty. It is a tough plant.. It's under control now because they are on top of it whenever it shows it's leafiness up to two or three inches but the fact that it's still perseveres is amazing. And this weekend I was a guest at a lovely New England estate that I once did a lot of work for, and as I strolled through the extensive gardens yesterday I noticed that the latest tenders are not vigilant and I saw baby not weed growing up in the peonies.. oh boy.. but other than inform me the owner I have no more skin in that game thankfully Now wonderfully retired I just get to go look at other people's work and smile
Yup it’s awful stuff. Glyphosate is the stuff to use. Probably what the army used too. The significant quantity of research pointed to Glyphosate as being the most effective chemical to permanently eradicate knot weed when used in proper concentrations at the proper application times. As you know, getting the roots and underground shoots to die is the only way to truly kill it off and not just have it come back weaker. Also really important to not let it go to seed. In England, you can’t sell property anymore with Knot Weed on it! That’s how bad it is.
I just found this out recently, as well. Wasted time doing the injection method only to realize that spraying the leaves in the summer/fall AFTER they flower is the only way to kill it properly. At least it doesn't have a waxy layer like ivy. So this makes it easier - just time consuming.
100%! I spray mine in the spring/summer just to keep them from getting big and healthy, but you def have to hit it when the energy is returning back to the roots.
It's all about timing. If you spray in the fall, after they've flowered, they're finally storing energy in their roots - before that, transport only goes from roots to shoots, not shoots to roots, so any weedkiller you use won't get to the roots where it's needed.
100%. I spray in the spring to keep them small and struggling and then spray through fall until they turn black. When I moved there were about 200 canes, roughly 12 feet tall, now I have about 50 that I don't let grow over 3ft. What a nightmare plant, honestly!
https://extension.psu.edu/japanese-knotweed Was able to get rid of mine in just two seasons following this advice. Basically cut it all back end of May, beginning of June. Let it grow back and use up resources. Then later in August/September spray glyphosate (8 weeks after cutting) so it sucks it into the rhizomes. Should mostly die off after first season, but repeat for second season as necessary being watchful for regrowth. I waited another season before digging up as much of the dead rhizomes as possible.
I love seeing advice backed up with actual academic links
This is so useful. This will be my third summer fighting them. I'll try the eight week method. But it'll be so frustrating watching them grow for 8 weeks.
Aminopyralid/Milestone is expensive but works better on knotweed than glyphosate. You just can't use it near vegetable crops especially legumes, locust trees, or on grazing land. That said, knotweed is a serious enough problem to warrant it
(4) Wait until dark, stab it through its heart with a crucifix
10 foot of soil?!
Lol 10 feet of soil
Thanks for the info. 12 GA seems quicker, but reason shall prevail. I’ll probably dig it up as I’m only seeing 5 chutes right now.
Don't dig it up, trust me. You won't be able to get the full rhizome and by digging it up it will cause it to spread and create more. You'll have dozens in just a couple months.
Lord, I’m getting so many different opinions here. What do you think I should do? I’m not saying any one person is wrong, I’m just going to wake up tomorrow and see what the general consensus is, because frankly, I don’t know anything about this.
They are right that you won’t get the full rhizome but if you get 80% then it will sprout again and you get 80% of it the next time and eventually the season will be over and what’s left will rot over winter. I’ve had success doing it but only on a small patch
Sell the house. That’s what I did. I did actually move but not just because of the knotweed. I dug it up before figuring out what it was. It made it angry and sent runners underground everywhere. If you are going to try and dig it out, destroy everything. Remove the soil completely in whatever way is legal or morally not reprehensible for you and replace with new soil. Otherwise go the round up approach. Or both. I tried injecting, cutting off in the fall and injecting stalks, spraying the foliage and waiting for it to die and then cutting. Knocked it back a fair amount. Then put blue tarp over the whole area and couple inches of mulch and some raised garden beds. Still had some shoots find a hole in the tarp a few times a year and had to spray and then remove some runners around the edges. After a few years it got manageable. Then I moved. Not sure how the new owners have fared. Honestly, Best of luck. On the plus side it actually particularily ugly and not poisonous.
Dig down to china, saturate with carcinogens. That’s the gist I’m getting. I smoke cigarettes, so I’m not opposed to using questionable chemicals.
Spray it. Wait for it to come back and leaf out a bit. Spray it again. Repeat for potentially years. It just takes patience
Glyphosate *
I wonder if tordon would work. It seems to kill everything
I know someone who does that with bamboo, do you have to worry about the chemical causing collateral damage to any plants that have been invaded by the knotweed?
I got sick to my stomach just seeing the picture. I have it here in New York. The first summer I cut and sprayed with round up every weekend, that only seemed to encourage it to spread outward. Last year I read to leave it be until fall, spray it after flowering but before frost. It killed me to just let it sit all summer. I see some sprouting so far this year. Hoping I made at least some progress. Good luck!!
https://extension.psu.edu/japanese-knotweed Best method is to cut in June-ish, let it regrow and spray in August/September.
This. I did this. Still seeing random sprouts but I also can’t get 100% sprayed because it’s down a ditch and coming from upstream the creek at the bottom of said ditch. So I constantly monitor for sprouts and get them sprayed young. Use the 360 roundup for extra protection.
I am planning on doing the fall treatment method this year as well.
Rip to your lawn, and good luck on your new battle. Not an invasive you want to ignore, if you value your property at all.
This isn’t MY lawn… yet. This is the product of some lazy person before me. I’m about to go all Hank Hill up in this bitch.
Bwaaaaaaah!
“Why would anyone do drugs when they can just mow a lawn?”
Use milorganite to get your lawn to grow. (Everything will though) super cheap and amazing. Your lawn will smell like a deuce for a day or two after though. Spend this year cutting out weeds. Seed in late fall. Cover with peat. (Thatch first if you are going to overseed) Next year will have a super green full lawn.
Just spent the better part of yesterday cutting all over 1ft. I plan to hit the patch weekly as this is year 5 of my war which I am not winning. Last few years I've gone with poison which just killed it all but the knotweed came back quickly. If I can't gain ground this year I'm calling in a pro, this shit is crazy!
Sounds like I’m lucky that I’m limited to just a few square feet of it, that I can tell. Only spot seems to be right outside my spare bedroom window. Probably just gonna dig the fuck out of that area and hope for the best.
Dig it up and make sure nothing is left. Don't leave pieces, clean it all up as some can grow into a few plant. Just a few feet should not be hard to remove but like others said be sure to dispose of it properly, check with your town. Sounds like you can beat this with a few hours of work, well worth doing it now before a 4 feet become 8 and then some. Good luck!
Thanks! Gonna tackle it tomorrow after work.
Don’t cut it! Spray with glyphosate in the fall before the first frost.
No, don't cut i! You need to let it leaf out and spray with concentrate BioAdvanced Brush Killer once per week and then only cut it down when it's fully dead. Cutting it or digging it causes the plant to react by accelerating its growth rate under ground and will cause new shoots to sprout quickly.
https://extension.psu.edu/japanese-knotweed As I wrote in another comment, you have to wait to spray after cutting. If you spray early it only kills foliage not the root system.
Sorry to hear you have this. FYI In the UK you are required by law to declare this when selling a house. It has to be declare even if it has been treated.
US here. Every house comes with a fifth of Bourbon and a shotgun. Honestly, I’m not sure about the laws here, but I had two inspections done, one from my lender and one from my own pocket, and not a thing was said about the yard.
From the comments here, I hope I never get this devil weed in my yard.
What’s your address? I’d like to send you something.
😂 I had to Google the horror. I read horticultural vinegar down the spinal cavity is a pretty solid. If it were me I’d do that or gasoline. No way it lives through napalm.
Lol too close to my house for an option that devastating. As much as I’d like to do it.
Well it lives through volcanic eruptions so probably just laugh at napalm
Oh no!!!! I'm on year 3 of trying to get rid of mine. Use BioAdvanced concentrate and spray it as it leaves out. Don't cut them down until they're dead, it will make them grow faster.
Can I ask where you're located? I'm zone 5b (northern IL) and we recently went through this. I had friends who were literally having nightmares about the knotweed in our yard!! Knotweed Excavation https://imgur.com/gallery/t8pu9KT When we first bought the house, we replaced and installed a fence for our dog, where the fence guys chopped down anything nearby, including the knotweed. When we had someone from a plant nursery come identify things in our yard for us, he called the cut bulbs "old growth peonies". I was watering the damn things until I was video calling with my mom and she said "those aren't peonies" (oh, how much I've learned since then!) Anyways - 3 years later and the method we've used was mostly successful. That first year, we let it grow and expend a ton of energy putting up shoots. Then we hired someone to pull it all up. If you let it sit out and die (or get sent for compost heat treatment) it's fine. But any bit leftover will try to grow again - if it has the energy. Our trick since has been to dig the root out as deep as possible, as early as possible so it doesn't get any energy. However, the only effective time to use herbicides is the fall, after they've flowered, when they're finally trying to store energy instead of use it. I never wait for them to flower before I pull them up, but if I see anything in the fall I do spray it. My extension office and city have been of no help in eradicating this. It has spread to all 5 neighboring lots, but due to our treatment plan, I only get a handful still popping up. Happy to talk details if you need it! You're going to want to control these as best as possible tho, as knotweed roots have been known to crack concrete (I'm concerned that there's siding at the back of your photo...)
Yeah it’s right up against my house. I’m just across the lake from you damn near in Michigan. Thank you for the info! I appreciate it :)
As you’ve seen in the comments, knotweed brings out the crazy in some folks. There’s a knotweed support group on Facebook that can be really helpful for guidance, but the group is closed for the season. It will open back up for new members in the winter. What I did: No cutting at all. No burning. No digging. In the fall, once it has flowered but before the first frost, spray the plants thoroughly with a glyphosate mixture at a rate of 3-4%. (You may need to spray it while flowers are still on depending on when your frost is.) At this time of the year, the plant is sending energy down into the deep tap root, and the low dosage glyphosate will slowly take the chemical into the taproot, killing it over a few weeks. A high-mixture percentage of glyphosate will burn the leaves and not harm the tap root. It’ll send out new roots during the winter, and you will find new shoots the following spring. Glyphosate treatment any other time of year will burn and kill the plant you see, but the deep roots will still live, and they will grow out and send up more shoots in a different area. (The same thing happens if you burn or dig it.) I followed this plan that was recommended to me last fall, and was 95% successful. This is a helpful resource: https://www.nwcb.wa.gov/images/weeds/Knotweed-Control_Whatcom.pdf
Almost wondering if this is from the piss poor mulch job that someone tried to do. The weeds seem a lot more concentrated within the mulch along my patio.
I’m pretty sure this is how I got it, I similarly have only a couple small patches in the mulched areas right next to my house. I think it gets cut down and sent off with yard waste to get mulched, then establishes itself at its new home when the mulch gets used 😭 Every time a new stalk pops out I’ve just been digging down as far as I can, cutting it, and applying 50% glyphosate straight away to the cut stem. I’m hesitant to let it leaf out and leave it all summer like the advice you’re getting here because I want to starve it out - it can’t expend resources to spread underground forever if it never gets sun. Since it’s only a small amount I just watch it like a hawk all summer and cut the new stalks immediately as they emerge. So far this year I’ve seen much less of it than last year, and hasn’t spread to any new areas yet…
I had this in the backyard of my NYC apartment. Could not get rid of it. This is going to be a lot of work to dig up all the underground roots and burn. This stuff is relentless.
If herbicides are ok, just hire a chemical weed control professional. I killed a lot of this for USACE and private landowners using aminopyralid. It won't happen in one treatment but it can be done.
Time to call in tactical nuke asap
An interesting video for you: https://www.youtube.com/watch?v=Oc_oJ2tuJ6Q
[Not to worry, I’m taking care of it](https://imgur.com/a/p1kzuFL) /s
Sorry, meant to reply to a different comment that was sarcastic, but it seems to be gone now… Not sure why it replied to your comment.
It's still funny.
Lol glad you think so. Hit or miss with guns on here.
Been battling this in my backyard since I bought my house five years ago..there’s a Japanese knot wood support group on Facebook you might want to check out; it has tons of good information. ETA: I just read through the comments on this thread and a lot of the suggestions and information given are inaccurate and ineffective, and could potentially make things worse for you. Japanese knotweed can grow through volcano lava, so most methods of removal just don’t work.
Depending on the size it will need stem injection with glyphosate to destroy it. This is at certain times of the year and has to be done more than once. Specialist company needed to do it properly. Waste needs to be disposed of properly and depending where you are there could be laws governing how it is to be disposed of.
Look up the facebook group Nixtheknotweed for a guide to killing it simply by cutting it to the ground with proper timing 3x per warm season for 3 years. Ignore the people saying it’s impossible to kill, you just need persistence and knowledge. It seems impossible if you’re ignorant of the plant and try to tackle it blind. Every time someone posts a photo of knotweed on the internet a bunch of dummies give their 101 impossibly laborious ways to wage war stated as fact. That’s not the advice you want to follow.
If you’re in Delaware I recommend contacting the Delaware department of agriculture for guidance. I thought we had Japanese Knotweed in our yard after seeing this post and they were very responsive, helped me accurately identify the weeds in question and gave me guidance on what to do. They said for Japanese Knot Weed, if it’s a new growth you can dig it out, then if it’s still a problem come late spring/summer spray it. https://delaware.gov/contact/
I read recently, the roots can go a meter deep. I'm so sorry for your loss...of lawn.
Dig it up and burn in burn can
RIP. cut that shit down and spray down it's throat with plant killer. Then dig up the bulb. Then do it for the next 4 years.
Roundup
It’s always knot weed
If that is knott weed it's healthy to eat. You can turn it into a fruit leather
Turn burn it
Japanese knotweed. Dig down 3' and 3' around but do so like an archeologist. Follow the rhizomes. They'll break off into tiny pieces if you cough or sneeze and each will reproduce an entire new plant. Dig it all up and find what direction it's running, it likely is elsewhere if you see one. The bigger and thicker, the more likely there's tons of rhizomes. I have mine mostly under control it's been a few years but I pluck starters every summer
As long as it hasn’t been sprayed you can eat it. Check out the Black Forager on instagram for more information. Eat the invasives!
Japanese knotweed. Inject roundup into the stem with a syringe. Digging it encourages spread of the roots. I had hundreds of these bastards in my yard when I bought my home. I managed to kill it all off after two years.
Any invasive in my beds get a loving stroke of glyphosate.
That is Japanese Knotweed and it's the worst plant in the history of plants.
Round up once it’s a foot or two. Coat the leaves.
Uh oh
2oz crossbow 2oz roundup mix with water in a 0ne quart water spray bottle. Spritz to wet not run off. Treat at first signs and continue to treat new growth that shows up.
Your story is so similar to mine. Bought a house and discovered this on my property the first spring/summer. We have garlic mustard too (it’s even worse if you can believe it) on the other side of our fence that borders a green belt. The state and county I’m in has a noxious weed department - they have been coming out every year to spray the knotweed and garlic mustard free of charge (well, taxpayer funded ha). Going into year 3 and the knotweed is almost all gone, and the garlic mustard starting to turn. See if your county has something similar! Edit: I tried mechanically pulling at first too, and it did fuck all. The root system gets super deep and wide spread and it’s almost impossible to dig out perfectly without fragmenting. I wouldn’t even try tbh.
I think pickling the young shoots can be tasty. Check me on that one before you try it.
Reading the comments this sounds like a plant that is the equivalent of a hammerhead worm.
Don’t touch it until you join the Facebook Japanese knotweed support group and do research on it. If you handle it wrong you will make the problem worse.
🔥🔥🔥🔥🔥🔥🔥🔥🌲🔥🌲🌲🌲
We tackled a ~20ft X 20ft plot of this a few years ago. First we tried cutting it, then pulling it, then I literally torched it, then we tried this stuff called RM43, total vegetation killer...It mostly worked, we still get a couple shoots every year but they are easier to pick/manage. I've heard using something like RM43 and then laying black plastic for about 5 years is supposed to get rid of it if you want to do the long slow game.
Sheet mulch the area. Gets rid of it (?) & improve the soil / aesthetics for some native perennials.
100 percent Japanese Knotweed!!
There’s another way. Make a fermented fertilizer with all your yard clippings and use it to fertilize a competitive but useful species e.g. mint or marigolds or nasturtium. More knotweed = more fertilizer. [link to fertilizer](https://youtu.be/6izQfXMO9nY?si=ubBLEooJ6UDLEnTR)
Japanese knotweed. Welcome to my nightmare. Best bet is repeated glyphosate but honestly you might have to wait until fall for it to make it down to the roots. The rhizomes are everywhere and the tiniest bit will start growing a new plant. Sorry
How big is the area? If budget is low everytime a small sprout come up dig beside is and get it from the deepest point. Add weed killer down there. Try to take it out in one piece and place itnin bin. Small pieces of root system can regrow. You can opt for getting concentrated glysophate and stem injecting it and just keep doing that until they are all gone. Wait til the olant fully dies before removing it. May even was to torch after pull to ensure any rhizomes on the surface die.
Well if you're alone is covered in that, you have to immediately have an exorcism. You're screwed.. Japanese knot weed once established is very difficult to eradicate. If the area is not really large, I would consider it covering it with plastic for a year lol It's that serious. You can spray it and it is possible to get rid of it but it is truly difficult. You simply can't dig it out even a tiniest little bit of plant will regenerate itself and only thank you for spreading it around and helping cultivate the soil. You can mow it and to mow it and to mow it and it will not go away. Persistent and the minute you stop oh boy up it comes..
I just pulled mine and planted other stuff that was local. Seems it was out competed. Still get one or two a summer, but I'd say it's mostly gone Reading the other comments it appears I did exactly the wrong thing. Seems to have worked tho
It is very nutritious when cooked!! Bon apetit 🥴 But seriously, it is detrimental to the environment so please do what you can to remove it
Have fun. I digged it out 1,5m deep. It still comes back. Worst thing ever!
Looks like bamboo. Similar to knot weed both vary invasive . Sad to say. But may have to treat area with heavy brush killer. It will kill your grass as well. You can try digging but the grow by spreading out under ground like rysome similar to ground ivy and mint. Once killed you can replant with grass seed.
If you wait until it goes to flower it’s at its weakest. Use a mix of Glyphosate and Crossbow. Anything short of killing it causes it to go in a defensive mode and puts all its energy into the roots.
Reynorea japonica probably incorrect spelling
Ever seen little shop of horrors
Make sure to add a shot of Dawn to your herbicide mix as some leaves are hydrophobic and your mix won't stick.
Thinking a cane Begonia ‘Angel Wing'
I don’t know the name in english but in german it’s Springkraut it’s highly invasive and spreats like shit so HANS GET ZE FLAMMENWERFER
Strongest weed and brush killer you can get and keep on spraying... Then spray more.
There is a Facebook support group for Knot Weed, join it and the community notes and members can help you in your journey to remove it. I'm on year two, not a lot left, previous owner did a chip dump and creates knot weed patches all over my yard.
I once purchased a beautiful variagated variety of it that looked gorgeous in the garden and claimed it was slow growing and not invasive. I had it about 3 years before I moved. Wonder how it's doing now.
It’s evil. Best of luck to you
If you can remove all the root ball cluster junk underneath. Then you may be able yo get rid of it. You just have to get ALL of it. Though. It’s entirely possible the ‘infection’ is too far gone. Good luck~
Keep snapping them off. They will not last forever.
Kill your lawn.
My pain and anguish can actually have purpose. If this is your owned home and/or you’re in this house for the long term you have some options. None of them are great. I had this at a rental property and I gave myself tendinitis pulling this crap up. You need to dig until you can find the main root system. Let me tell you if probably monstrous and the roots could be as thick as a carrot. I can send photos of what we dug up. Your goal is to unearth some big roots and chop an end off so you can submerge them in 5 gal buckets of salt water. Like 50/50 salt water. They will drink that water and it is the ONLY WAY to actually get to the whole root system. It will take months or doing this maybe even a year. Then you just continuously mow or cut down anything above the surface. But even if you tried like I did to pull it all out, you can never get it all. I had price growing from a 1/2inch piece of root that got left behind. I tried roto-tilling and that just spread it. You can’t cover it up it will find a way through. If you can figure out where it’s from and out in a physical barrier that could help slow the spread but it goes so deep it’s still a tricky thing. Please ask any questions you have. It would make that whole ordeal so much better if I can help someone else.
Japanese Knotweed. I’m currently trying to rid of an established hedge 100 feet long of this crap. Thanks for everyone else sharing their tips! This stuff is HORRENDOUS!
I managed to get rid of knotweed on a big section of my lawn without using chemicals by just mowing weekly during the growing season for... 5ish years. It's now contained to the woods between properties and doesn't sprout up through the grass anymore.
Propane torch
Plant golden bamboo around it and see if it shades it out.... /s
The bigger one looks like a Caladium. The smaller emerging stuff looks like Lantana, which can be a real PITA. When all else fails....Roundup
Those are a total nightmare, the root/rootball is huge and so hard to dig out. I’m so sorry
Welcome to hell
You poor bastard
Demon plant some a-hole landscape designer brought here Japan. Only thing I’ve seen beat it is smithing it in grass clippings. Honestly, I’ve tried everything from burning to chemicals. We had this wood line that this grew from it would invade into the grass one summer I just started burying it in grass clippings and I started gaining on it.
I have had success with mowing and carefully disposing of the clippings, and spraying with glyphosate in the fall after flowering. I also have dug out the crowns. If you keep on top of it and especially spray in the fall, you’ll get rid of them. I think your case of them isn’t nearly as bad as mine, as I had a lot of land filled with established ones. I read so many things online and I have not had any issues with spreading by mowing, but the issue I think is people may be careless with mowing and spread it elsewhere. Trust me, you don’t want to have to look at this plant growing all over your neighborhood, it’s very ugly. It’s super common where I live. If you don’t have many of them, you could also try digging it and throwing it away in the trash. Just dig the spot it’s in. They say if you break a root/rhyzome that it will just spread more, but I had success with this. I’ve been at it for 2 years now and I would say I am at 50% reduction of a very heavy infestation. Best attack is the glyphosate in the fall and keeping them from growing full size, and digging out any large crowns. I did glyphosate in the fall last year and that stunted a patch tremendously. You just spray the leaves with it. It will kill the grass around it but it’s worth it. I read somewhere that battling knotweed will need to become your new hobby. I think you’ll be ok, but you have to get started asap.
I am sorry. My neighbors have been dealing with it for years. I think this plant is Satan. Do you have anyone you particularly hate you know might buy this property from you? Have you thought about the witness protection program? If it learns where you move, there is a good chance it will follow you... Again, I am sorry.
Knotweed. I’m in the northeast and have dealt with it before. Let it grew until about June and then cut it down. In mid-August/early September you spray the plant with glyphosate. You need to cut it down in June otherwise the plant will be 10ft tall by the end of the growing season making it difficult to spray.
bind weed?