Resilience, thy name is goutweed

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Confession – I have a goutweed problem. Like many gardeners, I wrestle annually with this invasive perennial, but I don’t think I’m winning. In fact, I probably didn’t take it quite as seriously as I should have when I first noticed it growing in a corner of the garden about four years ago. It took mere weeks for that tiny patch to double in size and it’s now conquered three areas of my yard. After watching its steady progression in my garden, I realized last summer, that I needed to get serious about getting rid of it.

Goutweed was originally introduced to North America as an easy care groundcover, thriving in shade, partial shade, and full sun. It will also grow in a range of soils, but spreads quickest in cultivated garden soil. In terms of survival skills, goutweed is the cockroach of the botanical world. It produces a web of underground rhizomes from which each leafstalk emerges. The leaves are comprised of three groups of three leaflets and can be green or variegated.

This is an area I doused with vinegar last summer. All the plants were killed, but the goutweed has now re-sprouted.

This is an area I doused with vinegar last summer. All the plants were killed, but the goutweed has now re-sprouted.

Green goutweed, the type that I (unfortunately) have is a beast to eradicate, yet is not considered a noxious weed in Canada. Certain states, like Massachusetts and Vermont, have added it to their ‘Prohibited Plant List’ and it can no longer sold or traded. Incredibly, there are still garden centres in my province that sell goutweed as a groundcover!  The variegated type, often called Bishop’s Weed or Bishop’s Curse, is slightly less thuggish, but if allowed to go to seed, it can produce all-green, super-aggressive seedlings.

Related Posts: Smack Talking Weeds

Three ways to deal with invasive weeds like goutweed:

  • Cook ’em – Solarizing invasive weeds is among the most effective of the organic methods, but it requires time, heat, and the ability to put up with an ugly piece of plastic in your garden for several months. Begin by finding a sheet of black or clear plastic that is large enough to cover the patch, plus a few extra feet in every direction. Water the area well and cover with the plastic, burying the edges to lock in the heat and moisture. You can also use bricks to weigh down the plastic if burying isn’t possible. Under the plastic, the temperature can rise to 130 F (55 C), killing weed seeds, pests, disease pathogens, and hopefully, goutweed. Remove the plastic after 6 to 8 weeks and wait several weeks to see if the goutweed rhizomes survived and will re-sprout. If there are no signs of goutweed after a month, you might, just might mind you, be in the clear.
  • Smother ’em – This is the first goutweed-busting method that I decided to try, with varying success. Begin by mowing or weed-whacking your goutweed into submission, cutting it as short as possible. Cover the area with cardboard, again being careful to expand several feet past the goutweed, and top with a thick layer of mulch – bark nuggets, shredded leaves, etc. Wait. Smothering can take a long time – up to two years. If using an organic mulch like shredded leaves, you can add some soil and plant directly in the materials after a year or two, but only IF NO GOUTWEED HAS EMERGED.
  • Spray ’em – Now before you get your knickers in a twist, I’m talking about natural sprays made with citrus oil or vinegar, 20% horticultural vinegar to be exact. I have had modest success with this industrial strength vinegar, but it also takes time, perseverance and hot, dry weather. I’ve got the time and the perseverance, but the hot, dry weather can be tricky in Nova Scotia. Last summer I sprayed one of my goutweed patches with vinegar three times – mid-July, early August, and late August. The first dose did nothing. The second dose curled and browned the leaves within days of spraying. The third dose knocked it down, and up until a few days ago, I thought it was gone… but then I noticed the sprout in the above photo. That said, this was a dense 5 by 20 foot forest of goutweed last summer and I’m down to one sprout. I think it’s time to pick up more vinegar and tackle those other two patches.

Bonus advice – Move. This is the only known method for 100% elimination of goutweed.

Do you have goutweed? What have you found effective for controlling this obnoxious weed?







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19 Responses to Resilience, thy name is goutweed

  1. Barb says:

    OMG! Goutweed! ARRGH! I have goutweed in my garden (was my mother’s) that my mother accepted from a neighbour 30+ years ago as my mother ‘had such a lovely garden with lots of variety’. It became the bane of her existence. As she aged and was no longer able to weed as she once had–it took over–smothered anything worthwhile. So, 16 years ago when I inherited the garden, I swore I would conquer it in her honour! At first on hands and knees digging for all those white rootlets, then pulling and smothering. I still have some left and will now try the vinegar as I do use it for weeds in walkways. I have also planted divisions from my mother’s original huge, thick, blue hosta in the beds to shade the goutweed to death. I’m close, very close….

    • Niki Jabbour says:

      Oh Barb, we have so much respect for you!! You should be so proud of yourself for sticking with it.. we hope when you finally eradicate that last sprout, you share it with us and we can all do a happy dance! – Niki

  2. Kate says:

    I purchased a house which had garden beds rampant with goutweed (green) and gooseneck loosestrife. Awful. One bed was so thick with them that I solarized the whole thing. In the other, I dug up the entire section where they were thickest, going down a foot or so and dragging up great networks of roots. The pile was huge. Then I replanted the bed and watched for the slightest sprout of either one. When I saw them (of course they sprouted) I touched one or two leaves with a drop of roundup. Yes, I know. But this was war. The evil elixir only affected the target plants. It’s 5 years later and I still find sprouts of goutweed (the loosestrife seems to be gone), but very few. Best of luck to you!

  3. Steven says:

    I have almost given up on trying to get rid of the goutweed we have, and think I will call in an excavator to get rid of it. We only have a couple of patches, but it is stubborn to get rid of. We tried the solar method, but didn’t work. I haven’t tried smothering them. At least it isn’t knotweed!

    • Niki Jabbour says:

      How frustrating!! I have heard of gardeners who spent big $ to get it removed only to have tiny leftover pieces of the rhizomes re-sprout.. so if you do go that route, look for someone with goutweed experience! Sounds foolish I know, but no point in spending $ to have it return.

  4. Brett Apelgren says:

    Just a question, but was is it so bad to use one application of Glyphosate rather than repeated uses of 20% vinegar which is Glacial Acetic Acid and also considered a hazardous chemical ok?
    Over use of Glyphosate is bad but bombarding a plant with repeated doses of an acid that only kills the top growth isn’t good either. And over use of acid will change the soul ph and kill the life in the soil.

    • Niki Jabbour says:

      Hi Brett, i agree that too much vinegar can be damaging to soil and it has taken a few months for my soil to get back in gear.. with help from plenty of rain to flush the soil. I wouldn’t recommend using vinegar repeatedly every year, but in order to kill a stubborn and aggressive plant like goutweed, it is quicker than repeated hand pulling. Unfortunately, glyphosate doesn’t usually kill goutweed with one application. Like vinegar, it can take several. Whatever you choose to use, I would recommend gloves and eye protection. You don’t want either getting on your clothes or yourself.

  5. Glynis Thomas says:

    Darn, the band-aid has been ripped off again.

    Whoever said, “a weed is just a plant growing where you didn’t want it,” never had Goutweed! Or Spotted Knapweed; or Japenese Knotweed; or Rosa Multiflora; or Nightshade; or Colts Foot; or Creeping Buttercup; or Angelic; and with all these someone gave me a lovely little blue plant that turned out to be Creeping Charlie (it really was a creep). … I was away from home for a while and they all got out of hand. I was heart broken and utterly overwhelmed but I love my garden and ultimately decided my very diverse, natural garden had to be saved. So, the gloves came off … um, I should say went on. The Goutweed had even managed to smoother some small evergreens, found its way under patio blocks and wound its way through many tree roots. So here are my three “SUCCESSES” so far, I think, I hope … please.

    (1) YES,TO SOLARIZING. Especially for a large area. One layer overlapped with a second layer if its a big area (leave no gaps, nothing heavy, you want to get it hot). You can also leave the cover on (if its a big area be willing to leave it there for several years to interfere with any photosynthesis for any left over bits. Plus you absolutely have to ensure you are covering an area well past where the tops are visible. The next hard part is making sure the area is left clear for a couple more years so you can find those little pieces that somehow, someway, got missed. Mowing works well, as low as you can get. AGGRESSIVE PERSISTENCE for an aggressive invader

    (2) YES, TO SMOTHERING. The black plastic is in effect also doing this. But the paper, cardboard and mulch was a fail. However, as one area had shrubs solarizing wasn’t possible nor was digging out the shrubs. So, I did us use the paper and cardboard but then covered in and around my shrubs with high quality landscape fabric and mulched heavily with cedar mulch. Success has been in stopping the Goutweed from growing over three feet and smothering my evergreens.

    YES, TO DIGGING. Forget mass digging it up though. Too expensive; too likely to spread it around; and likely to be ineffective, if not carefully done; besides you’re also tossing the topsoil away. CAREFUL, METHODICAL HAND DIGGING will work for a small area aka 10 feet by 10 feet. I started at one side, and did a small section every week. I used a long narrow small “pry bar” and worked the soil up and carefully followed along each root until I found the new tip ends. Once I had the area done, I checked every week, then every month, then every spring and now three years later I found what I hope is the last piece at the outermost edge. Time to replant with what I want – things for bees, birds, butterflies and my family. PS Spring digging is the best, a little frost heaving helps the process.

    HINT: For perennials or small shrubs you want to rescue, so you can solarize, dig up, then in a large bucket spray the dirt from the roots and carefully remove the Goutweed roots – they are usually smooth and a lighter colour than most roots (you’ll get used to spotting them). Then pot your plant up, give TLC and DO NOT REPLANT for at least two years (yup two, three is even better) you need that time for the darn little piece of root you missed to find its way up, and it will. (Sink the pot in the ground so the rim is above the soil and you’ll have a temporary garden for a while but if a new Goutweed plant makes it through you can hall the pant out and very carefully remove the offending piece, if necessary using the above method.)

    Will have to track down the HORTICULTURAL VINEGAR for where none of the above will work (multi-stemmed, large mature shrubs).

    Now onto the next spot and the next and the next and … Never give up. Cheers, Glynis

    Also, the Nature Conservancy puts out a reference manual for invasive control at http://www.invasive.org/gist/products/handbook.pdf see chapter 1.

    • Niki Jabbour says:

      Hi Glynis. thanks so much for your detailed comment!! Great info! And I also deal with a few more invasives that you mentioned – coltsfoot in particular.. it’s a battle, but one that I don’t intend to lose! 🙂

  6. Cindi says:

    I also have the dreaded weed. I put cardboard and black tarpe, waited two years and all seems ok two years later. Now I have another patch and it is all under a very large rhodo. I know rhodo roots are very close to the surface so i am not sure which method to use to kill the goatweed. I just keep on cutting it to the ground but it seems to be getting thicker. I don’t want to kill the rhodo. Any suggestions?.

    • Sharon Boddy says:

      I eradicated a patch in one area of my yard by first covering it with cardboard (you can also use plastic bags or a tarp) then covering the cardboard with autumn yard waste. I made the pile about a foot deep and, after doing this for two years, it worked. You could protect the rhodo by cutting out the bottom of a large planter and placing it over top, or cut the plastic or cardboard to fit around it. Hope that helps!

  7. Sharon Boddy says:

    If all else fails, goutweed is edible..tastes like celery. I gave up and now just toss it in salads or make it into pesto. Take caution, however, there are some lookalikes like water hemlock (leaves on that plant are much longer and narrower), so make sure it’s actually goutweed that you have before noshing.

    • Niki Jabbour says:

      Yep – I’ve tried it too!! But I’m still determined to get rid of it.. almost there, just a few spots left 🙂 And great tip on being sure you ID your plant properly – always a good idea! – Niki

  8. Sharon Boddy says:

    Forgot to mention. At this time of year, when all plants are bedding down for the winter, rip out as much as you can before doing the cardboard/plastic/leaf litter thing.

  9. Stephanie says:

    I pulled as much as I could and then planted a native (ragwort) and the native is winning. It’s been two years and I rarely see a little goutweed coming up. Hoping for none this year. Learned about it here: http://www.humanegardener.com/how-to-fight-plants-with-plants/

  10. JFinnegan says:

    So appreciate that I have finally narrowed in on the correct identification. At the same time, so frustrated… last spring in what I have affectionately referred to as my “cutting garden”, I literally dug about 8 inches down throughout the whole bed (roughly 5’x20′) and picked the roots apart from the “good ones”, sifting down with my hands to be sure to get every last piece of spaghetti (root) that I could find. I kept up with any re-appearances throughout the summer, and felt confident that perhaps I had a handle on this. Not so! Spring has sprung here in Maryland, and there it is again- EVERYWHERE!!! I had tried vinegar in the past… this time, the glyphosate was my last straw. I applied one week ago, on a sunny 70+degree day…used more than I thought I needed/should, and today, a few wrinkled/browned edges on the leaves, and the rest look bright and happy. Where did this come from??? I thought perhaps it was a seed I bought years ago “faux queen anne’s lace” had finally taken hold… I was terribly wrong.

    • Niki Jabbour says:

      Oh, I can relate! It’s a terrible, terrible weed! I actually ended up pulling out a whole section of the garden where the goutweed was growing and am replacing it with a stone patio. So frustrating! I wish you much luck in your continued battle.. sigh.. – Niki

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