Help me kill the Goutweed (Aegopodium)

vicki_vale(z6 NY)June 25, 2008

Further to the post regarding the sale of goutweed:

Please help! The goutweed at my mom's house has reverted to the super-invasive green color type and is escaping into the lawn. It has already drowned out it's variegated siblings, overwhelmed the smaller shrubs, and engulfed all of the perennials.

How do I kill it? I am reluctant to pour Roundup on everything.

Will blanketing all the beds with cardboard & mulch for a year be successful? How much do I need to cover the beds, to prevent their roots from reaching horizontally underground and popping up even further into the lawn? Is a 2' wide "safety zone" enough to contain this beast?

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I hate to tell you but you now have a problem you may not be able to solve. I have seen so many attempts to snuff out this beast and all have been unsuccessful without the aid of something like Round-up and a massive amount of time spent on supervising the problem so it doesn't return.

Two examples...

Five miles up the road a neighbour finally decided to tackle the green goutweed (gg) four years ago by cutting it right to the ground, then placing a black cloth weed barrier, and on top of that placing a heavy mulch of wood chips one foot thick. The cloth was overlapped by 6 inches where it met. This area was on his front lawn, an area about 30 feet by 100 feet.

Next year the gg started coming up where the cloth had been overlapped! You could see the rows. He uncovered the whole thing and this time placed 3 thicknesses of weed barrier and covered again with the mulch.

Forward to this year - it's back! EVERYWHERE!

Example #2

Neighbour a few houses down let this pretty ground cover grow under her trees. Then it started taking over the lawn. They have a walkway which is poured cement leading to their house. It is 4 feet wide, not sure how deep. That's the only thing which is stopping it from invading the other side of the property for now. She also meticulously deadheads all flowers so there are no seeds.

Don't waste your time. Go for the Round-up. I'm usually not so aggressive about plants, but this one and Japanese Knotweed and Purple Loosestrife are big problems and I invest too must time in my gardens to even consider being nice to these thugs.

    Bookmark   June 26, 2008 at 8:38AM
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I agree, be vicious!!! Even with roundup you may have to go to the extreme of covering it and mulching to try to choke out survivors. It should be outlawed. Can't believe they still sell the stuff.

    Bookmark   June 26, 2008 at 10:51AM
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I also suggest installing an edger temporarily to contain invasive roots. Do not attempt to pull out the plant lest you inadvertently create more new plants. Use roundup and allow the herbicide to trickle down to the very roots. Then mulch heavily.

    Bookmark   June 26, 2008 at 1:53PM
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When using roundup on aegopodium the best results occur on new growth. Use a string trimmer (it is the easiest)-cut the aegopodium to the ground. Wait for the new growth then apply the roundup. It will not eradicate completely but kills it quicker than applying to mature growth. Good luck.

    Bookmark   June 26, 2008 at 9:25PM
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cookie8(zone 5 ON)

I put down weed barrier and 2 inches of river rock and it still came back! Get tough.

    Bookmark   July 2, 2008 at 9:51PM
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wyndyacre(z6B SW Ont.)

The method described by Tegwyn works very well....I used the same method to rid myself of a very large (30x50') area of goutweed except that I ran it over first with a lawnmower with a bagger on it.
I then sprayed the new growth about a week later (it grows up quickly) with Roundup. Cutting it down allows you to spray new growth which takes up the Roundup spray quickly thru photosynthesis. It also allows you to use less spray because you are spraying short new growth instead of all that tall older growth.

It helps if you know how Roundup will only kill plants that are works by being drawn into the root from the leaves by photosynthesis. The plant must be actively growing and have foliage. Saturating the soil will not kill plants and will only be a waste of spray.
It will not kill neighbouring plants that the spray has not will not be picked up by those plants from the ground thru their roots. If you have desirable plants mixed in with the gout weed, you can cover them with a plastic bag or nursery pot temporarily while you spray.

I recommend buying the jug of concentrate and mixing your own spray according to directions. It seems to work better than the spray bottles of premixed stuff. Perhaps they are a weaker mixture.

Then just remember to wear plastic gloves (I use surgical gloves that can be thrown away), rubber boots that can be rinsed after (not fabric shoes) and last but not least....begin spraying at the farthest point and walk backwards as you spray so you don't walk thru the sprayed foliage. You don't want to end up with footprints of dead lawn where you walked after with Roundup on your boots!

Don't laugh....I've seen many people do this! :)

Don't allow your pets or children to run thru the area while it is wet. It is safe when dry and breaks down in the soil quickly. You can plant in the soil in 4 days although you won't see the gout weed dying for about 2 weeks.
Be does work!

I only had to respray some tiny pieces the next year, up against rocks or desirable plants that got missed the first time.

    Bookmark   July 8, 2008 at 7:08PM
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liatris52(Cdn z6b)

Our neighbour had a flourishing garden of goutweed and when we moved in, we were dismayed to find it marching right across our lawn and garden. We've been here five years, in an inner city neighbourhood of Toronto. We've controlled the goutweed by pulling it up, pullin it up and pulling it up some more. Then lots of mulch. We've planted some tall plants like cupplant that shade out the goutweed and lots of ferns that do the same. It's not gone but a has retreated to the back corner of the lot where it comes up from behind the back neighbour's fence. Our neighbour to the south gave up on his back lawn, covered the whole thing with about three inches of cardboard and mulch on top of that. I bet when the mulch and cardboard break down we see goutweed again!

I thank you for your round up tips and will keep that in mind should the invader again push itself forward -- which wouldn't surprise me in the least.

By the way, I eat the goutweed. It's tasty and at least I get something out of this pest.


    Bookmark   July 15, 2008 at 7:32AM
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bluebloom(z8 PNW Canada)

Oh my, seeing this post reminds me that we have some (variegated) goutweed popping up in a spot that we painstakingly cleared of it over 10 years ago! At that time it was the main "garden" (along with chickweed) under a large conifer when we moved in, and there was a large patch in the back also. We went over every inch on our hands & knees, digging down with a hand fork as far as we could see roots, and taking all out that we could see.

In a couple of difficult spots (eg. hard inpenetrable soil or in between rocks/fence), we carefully painted a little bit of Roundup on to leaves that we bruised. Can't remember what we used to do that (that may have been the last time we used Roundup - but might be trying it again in a similar careful/limited fashion on a weed blackberry bush that is too difficult to get all out by hand digging).

Early on we had put some topsoil/compost mix on that area, then a few years later extended the garden by making a lasagna bed which also included that area to some extent. But I guess we left at least one little determined piece of root behind.

JD - interesting that it's edible! Wonder how the variegated version compares to the green for taste/edibility. Funny I actually like the looks of goutweed now more than then, so MAY pot some up (on concrete, and no letting flowers go to seed!!!)... bonus if it can be harvested for good eats.

    Bookmark   July 18, 2008 at 7:45PM
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mike_in_paradise(6U 5A Cn Jun9Sep29)

I cleared out some property that I bought 3 years ago. This was heavy brush and cleared in the fall.

When I went back the next spring this is what I found. Very evil stuff.

By mikeinparadise at 2008-08-01

At least it hid all the stumps...

I pulled all the stumps and tilled it and of course it came back.

Soooo I decided to try planting clover to see if it would smother out the goutweed. So far it is doing a good job but it needs to keep spreading. Not sure how it will work under the trees as I have not done that part yet.

By mikeinparadise at 2008-08-01

By mikeinparadise, shot with Canon PowerShot A20 at 2008-08-01

Of course this will only work for a lawn and then you end up with clover but I am liking the clover.

    Bookmark   August 1, 2008 at 1:43PM
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hi, I have goutweed in flower beds which I'm controlling (just) through digging and physical removal, but now it's spreading through my lawn. Will encouraging the growth of the grass control the goutweed, and what would be the best way to do this? Thanks

    Bookmark   August 5, 2008 at 12:50PM
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I know that it's been a few years since this post was written, but I just wanted to add a special note. Anyone who lives in eastern NA & thinks they have a problem with Goutweed may want to double-check they don't actually have Virginia Waterleaf (Hydrophyllum virginianum). It will naturalize quite quickly, especially in rural areas & looks similar to Goutweed. The flowers are very different between the two, though. Goutweed has a taller stalk with a Queen Anne's Lace-type flower, whereas Virginia Waterleaf has small clusters of drooping lavender, or white bell-shaped flowers.

    Bookmark   May 4, 2013 at 9:30PM
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I wanted to also add a picture of the leaves of Virginia Waterleaf (Hydrophyllum virginianum), a native of eastern NA. Young leaves can also have white markings that look like drops of water, or a slightly faded variegation. The leaves & spreading habits are very similar to Goutweed. Please see the post above for a picture of the flowers, which are quite different from the taller flower stalks of Goutweed.

    Bookmark   May 4, 2013 at 9:46PM
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Does variegated goutweed always turn to the nasty green stuff if it is not obsessively watched?

    Bookmark   October 24, 2014 at 6:39PM
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