PlantFiles: Japanese Knotweed, False Bamboo, Mexican Bamboo
Polygonum cuspidatum

In the UK it is an extremely invasive, practically ineradicable weed.

This plant was out of control at my new house. Though it will take me a few years, I will conquer it. BEWARE: Do NOT plant this anywhere!!

This is indeed a VERY invasive weed. When we bought our place in Maine there were several stands of it and we were told that it's literally impossible to get rid of. Contrary to what we were told, we HAVE irradicated it in one large place where it was really an ugly landscaping problem.

We began the project in early spring, but I think you could do this at any time of year. First we moved, scythed, dug out and pulled up all of it we could. Next we lay porous landscaping/ground cloth over the whole area, using lots of pins and very generous seam overlaps. On top of that we put down about 4" of topsoil and planted grass seed. The idea was to suffocate and exhaust the stuff. It's worked very well and is almost gone. We did have some work it's way up through the seams and some little guys pop up around the edges and through several tears in the fabric - we just keep pulling them up. Over time they started getting weaker and weaker and smaller.

Finally this year, we've had almost none of it return. The grass there isn't doing very well because we didn't make the soil deep enough, but at least half our yard isn't lost to knotweed. We may not have totally irradicated it, but . . . it's a pretty good solution for some situations!

Suggestions for improvements to this method:

1. If I did this over again, I'd actually tuck&fold the seams to make them even more impenetrable, and I think we would have defeated it even sooner!

2. Make the area as smooth and free of sticks and roots as you can. Our area was partially woodsy and there were some raspberry plants we didn't remove carefully enough - their stems caused holes in the landscape fabric where several knotweeds popped up later.

3. My next problem is how to improve the lawn there - the soil is not really deep enough for it. I'm considering removing the topsoil and grass - and starting over with more landscape cloth and adding better, deeper soil.

The False Bamboo has been a thorn in the side of the city development office where I live. It is an extremely hardy weed which can only be killed by basically killing the ground it resides in.

I like the landscape fabric idea to choke it out, but I would add this to the recommendation: Instead of using landscape fabric, use the same rubber membrane that roofers use on flat roofs. It is stonger, thicker, and all but impossilbe for plants to poke through. It also has a greater lifespan than frabic and comes in wide sheets. This also works great under decks and patios with gravel or sand on top to control weeds under these structures.

The agriculture guru from my city recommended this though. There is a chemical herbicide for woody stemmed weeds called Crossbow from Dow Agro Science. It sells for about $66 a gallon here in it's concentrated form. It gets mixed with water (he even recommends doubling or tripling the dosage to kill this particular plant), and then gets sprayed on. This will kill everything in that soil! The grass and any plants you want to keep are also goners. He recommended doing this over and over until there are no more shoots popping up and then to re-fertilize the area and start over.

I hope some of this helps. Good luck and may fortune smile upon you.

Since I planted it last year the Japanese Knotweed, Fallopia Japonica, forms a beautiful blind behind my barn. It is fast-growing, has great foliage and provides an attractive display of white flowers in late summer, like white lilac, or some of the elderberries (sorbaria sorbifolia). As a precaution, it should be planted inside a defined border where it cannot escape, like a mowing edge and/or thick pavement. Its controversial press shows that a 'weed' is only a weed where it is not wanted. If you are not convinced, check the scent of Joe Pye Weed or Butterfly Weed, or the great foliage of Variegated Bishops Weed.

If you plant this, you had better start saving your money, cause your gonna need a lot of roundup. This got started in my yard from a piece on a backhoe bucket ( at least thats all I can figure out ). I found this on another site: "Their rhizomes spread underground 25 feet in all directions, sending up shoots tough enough to pop through pavement." another site I read a few years ago said roots up to 60 feet deep. But I finally got rid of it ...........I moved : )

I love to consume polygonum cuspidata...AKA Tiger Cane...or Japanese Knotweed. I would like to purchase a live plant to propagate.

There are several stands of this in my neighborhood so we'll have an invasion for many years. I first saw it when I bought my old house - a large tropical looking plant was in the back yard - a friend said KILL IT NOW - IT'S BAD! I decided to wait till fall to hack it down - and that was long enough for it to send roots far far away. I'm still trying to find and pull the long roots and stop it from coming back.

They have insignificant white blooms, then unfortunately, also throw seed. Even Round Up didn't stop mine, and I am about to try that again...along with some violent shovel work. Please don't let it get a foothold in your neighborhood.

This is an obnoxious invasive that should never be planted.

Noxious weed in WA state. Need information on how to eradicate!

"In 1981, The Wildlife and Countryside Act made it illegal to spread Japanese Knotweed." Don't plant it in the UK - it's extremely invasive. If you have some in your garden, keep pulling it up and burn it.

Japanese knotweed came with the house I bought four years ago. I did pretty extensive research regarding getting rid of it, and tried several things. The most effective is just to spray the leaves as it comes up in the spring, using a heavy councentration of Roundup. I have one very large stand under control--it is almost eradicated, but it will never be completely because it grows along the stream behind our house, and I don't use the Roundup anywhere near the stream. There is another stand behind our barn that I haven't concentrated on, although I spray the perimeter to keep it contained. I will probably continue to let it exist and try to control its spread because I don't need any more land to mow, and it does provide a nice screen.

DO NOT PLANT IT, EVER. Also, don't bother to try to dig it up. And DO NOT discard any piece of anywhere, including the town dump--it's just mean to other people.

AWFUL! It is choking the riverbank and elbowing out native species. Just as bad as blackberry bushes here. It doesn't even look that nice in my opinion. You are out of your mind if you plant this monster.

I will echo the sentiments expressed by all others who posted a negative for this plant. Difficult if not impossible to contain without labor intesive removal combined with chemicals. This plant will get away from you as it repeatedly escapes cultivation.

I live in Cornwall, in the south west of Britain, where the climate is damp and mild. Japanese knotweed is a major invader in this area and hard to deal with because it is an enthusiastic vegetative reproducer. Our local horticultural college is carrying out experiments to ascertain how best to get rid of it. However, I have just heard a report on the radio from a member of a group of gardeners who take care of a local cemetery. They have problems with knotweed too but seem to have round an effective -- if perhaps rather labour-intensive -- way of getting rid of it. They regularily pull it up wherever it raises its ugly head and then throw what they have pulled onto some raised surface: pallets, stone or concrete slabs -- where they leave the knotweek to dry out completely before disposing of it. Apparently this is effective. The regular pulling weakens the plants and drying out stops the reproduction which can happen if you try to compost it.

A neighbor gave me a cutting of false bamboo from her garden about 20 years ago. I planted it by my rabbit barn mainly as a sun screen, but I also liked the tropical look of the plant. I knew nothing about how to grow or plant it, but it grew into a large bushy crop in no time. It is extremely hardy, and I'm sure it would have grown out of control if not for the rabbits, who really like to nibble the new shoots. They also like use the base of the plant as their potty. In the last 20 years it has not grown beyond the 6 square feet or so of ground I first planted it in, and I've had no problems with it in the rest of my yard. However, my neighbor has spent the last 20 years trying to eradicate it from her garden with only limited success.... perhaps the secret is to use rabbit poop.

This plant is terribly invasive and is on the Washington State Noxious weed list.

Have tried to get rid of this for 30+ years, it came with the house. It is a constant battle. I try to dig out what I can when I see it popping up.

The only good thing about it is the old dried stocks will make a loud crack when you add it to an outdoor fire!

There is a large stand of this noxious plant behind my stockade fence and I have been fighting it for the last 9 years. It sends up sprouts every spring and I attack it with a shovel and try to pull up as much root as possible. This battle goes on all summer and the worst part is that the sprouts and stalks ( if they aren't caught in time) grow right through other plantings like strawberries and iris, etc. and controlling the knotweed results in damage to desirable plants.

This noxious weed is one of the three main invasives I see taking over the Alki Peninsula. Ravines and empty lots in my neighborhood are full of it where they should have native elderberries and the like.

I've been growing this plant for more than 25 years. It makes a great privacy screen. I keep it under control by pulling new wandering shoots. My neighber even ask for some plants. He also enjoys the living privacy fence they create. So the plant is alive and well in southeastern Michigan.

It is growing adjacent to a creek. It dies back completely in the winter when the temp sometimes goes down to 10 or 15 degrees and stays for weeks. I pull it all out when it first shows up, but two weeks later there is even more of it. I would never use poison close to a stream (or anywhere else for that matter) so guess I am stuck with pulling, chopping, glaring, and cursing...:) I live in Lake Stevens, WA.

All you negative comment folks are missing out on a long life!

This plant contains in it's root, a recently discovered elixir made from grapes called resveratrol. It's all the fashion to take this in the alternative medical world, for all kinds of conditions, and lately it's been tested in 500mg/day doses to be a cell rejeuvenator. Besides, as a pesticide, the extract of the root has been sprayed to give plants more resistence to molds and fungus, such as powdery mildew.

I just discovered one company that gets their resveratrol from Giant Knotweed, another name for Polygonum cuspitdatum. I'd say you have a wealth of health in your landscape if you're blessed with abundance of this plant. Dig up the roots and make tea, and live happily every after.

And, it's also a Chinese herb, which you have to pay good money for, but, that will at least let you check with an herbalist to be sure it's good for you.
Here's one site I checked for Hu Zhang (the Chinese name) [HYPERLINK@alternativehealing.org]

On this site they say the herb prevents thrombosis of the epithelial cells in the arteries ... Other doctors say it helps memory, controls blood sugar, and that it actually helps the cell normalize.

Don't be so quick to pull out the "weeds" in your yard. Native Americans believe that what grows around you are the healing plants you need. Take another look. The internet might help you identify your health problems, through the kindness of the weeds in your backyard.

Be Well

Yes, this plant is invasive - around Dutchess county, NY it is a roadside weed. We have controlled it by mowing and pulling up new shoots in spring. That being said, the plant makes a great instant screen, growing 10' or more in about a month. Late summer. another bonus - bees love the small white flowers that appear. Since our north american honeybee population is declining, and I use beneficial insects in my organic gardens, this is a positive thing, although someone else may find a bee and wasp attractor less than desirable. One last thing - do not plant near foundations as it eats concrete if left long enough.

It is an on going battle to rid my garden of this plant.

This plant was growing in the back corner of the yard when we purchased our house. My husband was actually fond of it, but he finally agreed to let me mount an attack effort on it. We tried Round-up, digging as much of the roots as possible, etc. Nothing worked. We turned off the water to the area (we live in the desert!) and actually trained our dog to trot out to that corner every time he needs to do his business . . . but after all our efforts for four or five years, the stuff still manages to come back with a few shoots every year. Unbelievable! The dead stalks do serve one useful purpose; I break them off every spring and use them as unobtrusive supports for the peonies.

I hate, hate, hate this plant!! I inherited it when I bought my house and have been trying to get rid of it for 4 years. It covers almost a 1/4 of woodland property and has choked out trillium, jack in the pulpit, mayapple and many more desireable plants. I dig and dig and pull it out frequently and I'm making some progress, but very slowly. This stuff laughs at Roundup and I don't want to use more chemicals due to the sensitive native plants and wet woodland area it is in. Another note - I am a horticulturist and in Michigan it is illegal to plant Jap. Knotweed and/or knowingly grow it. A hefty fine can result. Do not plant Jap. Knotweed.

Maybe I should have looked further---- My knotweed fits all other discriptions except MINE has the most beautiful pink/red seedheads in the fall that almost GLOW !
I love this plant. It does spread but I dont mind having to control it. This year I cut early sprouts - to a foot high in size - and made soup with them ( web has recipies ).
Geno

This is one of the only plants I would never recommend anyone plant. Here in upstate NY (I can't believe someone in this area actually planted this thing), Japanese knotweed is pretty much taking over all the areas alongside creeks that furnish paths for wildlife. It forms huge thickets, crowding out every other plant form, and nothing can eat it. The flowers are usually so sweet that their scent is sickening, but this year in addition they smell exactly like tom cat pee. And this plant can grow through 6 inches of pavement. Garlic mustard is as nothing compared to it. As for harvesting the roots for alternative medicine, don't make me laugh. The roots of a healthy patch of Japanese knotweed are like solid wood. So don't plant it, please!

I have hated this plant for two years when I saw it in my friend's backyard when he moved. Now, two years later since I have moved into a new home, I have inherited my own rather large infestation of this foul and cumbersome weed. Just in the past few days, I decided to look it up and finally found out its name. Now that it has a name, I hate it even more. I actually have been dreaming at night about cutting it down, that's how obsessed I am with erradicating it.

Thanks for all of the notes on getting rid of it. The only problem with my land is that the knotweed crosses over property lines. So I will do my best to stop it to where my land ends, then continue to fight it every year for the rest of my life. I only have flashes of myself when I am 80 years old, out back with a machatte, cursing this living garbage for the next 45 years.
Ugh.

I live in France where this plant spreads mainly by folks buying gravel/sand/etc that came from infested river banks, among other means of propagation. I would call it a hideous pest but in fact it's rather pretty. Unfortunately its invasive nature and incredibly rapid growth rate would still make me call it hideous.

I don't have any on my 4 acres yet but if some shows up I am glad to have found this website to learn more. I don't know if I can buy Crossbow from Dow Agro Science here in France but if Knotwood rears its ugly/pretty head I will find that out quick. Else I'll use repeated Roundup until it's dead. We have no creeks on our property to worry about polluting with Roundup. Not that I like resorting to chemicals from evil mutinational corporations.

Nobody talks about goats. Won't goats eat this crap up?

Ceferino
Alsace, France

I'm on the fence. I have the ornamental 'Variegata' which I was told is not as aggressive. I have some in the shade that is still tiny after 3 years. But I also put some in a sunnier area (3-4 hrs) and that got a little scary. This past spring I saw some shoots go under a stone border and pop up on the other side in the lawn.

So I just pulled all of it out last night from the sunny area. I made some divisions of it in pots with the intention of planting them in other shade locations. But now reading all these negatives, I am quite afraid to do that.

I did take care to keep all the parts of it separate from other yard debris. My gut told me that would probably be wise but I was unsure how necessary a precaution that was. Boy, I am glad I did that after reading all these comments. I have it all in a black plastic back that will go to the landfill, but now I am not sure if that is good enough. Maybe I will dump it all out and let it dry and fry to its death first.

And I think I will also revisit the area where it was and dig around for more roots. I think there was a big root growing into a boxwood that I kinda disregarded.

Listed on Minnesota DNR invasive list
"Ecological Threat:
Japanese knotweed spreads primarily vegetatively to form dense thickets that suppress native vegetation.
It can pose a significant threat to riparian areas, such as disturbed stream sides, lakeshores and other low lying areas, where it can rapidly colonize. It tolerates full shade, high temperatures, high salinity and drought.
It is currently occurring from Maine to Minnesota and south to Louisiana and scattered in midwestern and western states. It was introduced to the U.S. in the late 1800s for ornamental purposes and erosion control."

The most current name is Fallopia japonica. This is a invasive weed with no redeeming qualities and is likely one of the worst weeds out there. Research shows that this plant has begun to hybridize with a closely related introduced species (F. sachalinensis) and their hybrid, F. x bohemica, has even greater potential for further spread than its parents.

I had never experienced the vile plant until I moved to upstate NY. The previous land owners planted several stands of it to hide the garbage dumping that had been done all over the property. Shame on them! I cut and dug and waged war all fall on a single stand-only to see it return in double measure the following spring. I have read that in some places it is illegal to bring this plant in, due to its invasive qualities. And yes, when you pile up the canes to burn, it sounds like artillery fire! My neighbor two doors down came over to see what kind of gun or M-80's I was setting off. I am back in MI now and if I never see another one of these horrible curses, I'll be a happy gal. phooey and bleah!!!

Misery loves company and I laughed through most of the comments, only to be slapped into seriousness by the few people who praise this plant.
We did the dig out, cover with heavy duty landscape frabic and then with 1-2' of dirt when we moved here. Problem is, you'd have to extend the landscape fabric at least 2 yards past the dug out area, and we couldn't due to our neighbor's trees. And we couldn't attach the landscape fabric to our own garage to make a tight seal. We're forever mowing new sprouts. This just makes the plant mad -- last year, it broke through the concrete floor and is now growing happily inside the garage!
At my first house, I had monstrous Alianthus and went through many truck jacks and come alongs pulling those out. Trying to jack a huge crown of knotweed is a method of propagation.

Will spreads by sending rhizomes at least 20 to 30 feets away from the parent plant. The only nice thing is that you can use the dried stalks as stakes but still weak compare to bamboo stakes. I have been wondering if they can be used for industry product - they have plenty of cellulose - for paper, ethanol, or for fires that produces energy when shredded and compacted together in a block - at least find a use for them as they are hard to get rid of.

Our small lot was surrounded by knotweed on three sides... I can't say that it's eradicated, but once I adjusted to the thought that I'd just have to do knotweed patrols all summer, it's been ok. A boundary area of mowed grass, even without any landscaping fabric under it, stops it pretty well--or at least, keeps it contolled. I believe that the knotweed becomes confused and confounded in its efforts to grow in the lawn--it keeps trying to come up, keeps getting mowed down, and gradually loses a fair amount of vigor. I haven't had problems gardening in the areas beyond the mowed strip--very little knotweed arrives there, and I can easily pull out those few light surface roots once in the spring. Also, the dense shade of our conifer border slows it down enough for me to have a fighting chance--I go out every couple of weeks and pull it or wack it with a handtool. Frequently, I can talk my boys into doing this for me--it's fun and easy to chop at, when it's young. I dry the roots in my driveway.

The only thing that I have found that works well for killing Knotweed
is stem injection. I had to shell out the money for the specialized tool and it's very tedious injecting each stem, but it works.

I live in Connecticut and this weed is very invasive. I have failed so far in getting rid of this weed. I'm going to try Spectracide Brush Killer it says it will kill Knotweed but its not specific about the Japanese kind. We're going to dig down 6" - 12" (spray with weed killer) and put down weed blocker fabric with staples to hold it down in place. Then put down fresh top soil and more weed blocker fabric with staples and mulch. We never plan on planting anything here because we're afraid the Japanese Knotweed will grow back. I hope this works! :-)