Susan Harris
All about gardening the eco-friendly way, by Susan Harris and 22 other garden writers and experts.

When good people use Roundup

March 8, 2008 · 28 comments

Responses to GardenRant reviews of The Truth about Organic Gardening revealed very different attitudes toward Round-up – not just from our commenters but even between Elizabeth and myself.  Most of us agree it SHOULD be avoided but then there are situations where we ask:  "What’s the better alternative?" and no answer is forthcoming.

In the "It Could Be Worse" Camp

Here’s what Jeff Gillman has to say about Glyphosate, the active ingredient in the top-selling herbicide in the world, Roundup (made by the company we all love to hate – Monsanto).

After declaring that hand-weeding is always the best choice for the gardener and assuring readers that he’s NOT be a fan of synthetic herbicides,  Gillman writes that "Glyphosphate and glufosinate ammonium are probably the safest herbicides to use when preparing ground for planting because of their ability to kill most weeds while maintaining a short life in the soil."  They’re "relatively safe for humans and the environment if they’re used in accordance with their labeled instructions," though under "some easily conceivable misapplication scenarios, Roundup could have deleterious effects on the environment," especially to frogs, and that’s mainly because of the inactive ingredients (soaps and oils) that the glyphosate is mixed with.

Gillman goes on to explain the new rating system called the Environmental Impact Quotient (which assesses risk to farm workers, home consumers, and the environment) and urges their inclusion on all labels.  Here’s what surprised me:  The EIQ of Roundup is only 15.3 (on a scale of 1 to 100), compared to, say, organic horticultural oil, which has an EIQ of 27.5 because it can hurt beneficial insects and plants.

To Prepare for a Meadow

The earth-huggers at the American Horticultural Society first tried creating a meadow organically but ultimately prepared the site by using Roundup.  The road to Roundup included first  applying for permission from the county to do a controlled burn, a request that was turned down.  Next, they tried preparing the meadow by tilling, but that only unearthed decades of pokeweed seeds.  Finally, they used Roundup under carefully monitored conditions – no chance of rain, etc. 

Gilman notes the exact same problem with tilling, adding that it also can cause erosion and make the ground susceptible to compaction. "So why not apply glyphosate and allow the weeds you’ve killed to work as mulch?"  But others disagree and suggest instead that that black plastic is the best way to clear land of vegetation.  Ah, but that method kills all the beneficial critters in the soil, though only for one season, I suppose (they’ll return with the application of organic matter).  I remember hearing soil food web guru Jeff Lowenfels (author of Teaming with Microbes) declare his hatred for plastic because it destroys the soil-food web but wonder what he’d recommend instead.  Roundup? 

To Remove Invasive Plants

Another Roundup-related controversy arises from its widespread use to remove invasive plants.  But even in the service of that universally accepted good cause, its use is criticized.  Faith Campbell of the Nature Conservancy, for one, gets slammed for using it in the removal of invasive plants, despite her standing as a "rabid environmentalist" (and I SURE wish I remembered where I saw that characterization).

To Remove Hard-to-Get-To Plants

Cass Turnbull recommends it when you can’t dig something out – maybe because it’s in a rockery or has its roots entwined in a plant you don’t want to kill.  She keeps small bottle of paste+brush containing Roundup in her pruning bag when she works.

Yours Truly

I confess to a lack of purity in many things, including my adherence to strict organic practices.  So when I discovered poison ivy coming up from beneath layers of other groundcovers, I squirted its leaves with the systematic herbicide that does the job.  I think I’ve finally tackled the poison ivy population on my property but this season I plan to go after another hard-to-get menace – the creeping euonymus at the base of my big ole white oak.   If there’s some other way of getting rid of it without endangering the tree and the other plants it’s entwined with, I’d love to hear it.

How Roundup Works

According to sources I trust, it does NOT poison the soil.  It’s a systemic, which means it moves from the leaves you’ve just sprayed throughout that one plant and kills it.   Nearby plants are not affected unless your aim is really bad, or it’s a windy day – and just DON’T DO THAT. 

More Don’ts

Also don’t get it anywhere near water, because it IS toxic to aquatic critters.  And using it regularly to kill routine weeds?  Ugh.  Why not prevent weeds and when they grow despite your best mulching, just use a little muscle? 

There’s a good summary of what’s known (and hated) about Roundup and its maker here on Wikipedia.


1 Ann March 9, 2008 at 7:49 am

All I know is that when I asked my neighbors on either side of my yard to stop using Round Up along the property line, my toads returned. For most gardeners, there are other options besides Round Up. We’re not all trying to start a wildflower meadow.

2 admin March 9, 2008 at 8:01 am

Sounds like your neighbors are using it indiscriminately, near water, and should cease and desist!

3 Ether March 9, 2008 at 7:18 pm

I’ll admit- I’ve been trying to figure out a non-roundup method of tackling bind weed in my gardens… and I’m not coming up with much that won’t murder the rest of my garden.

This paste idea seems promising…

4 Layanee March 10, 2008 at 11:01 am

I believe in the system of organic gardening! That said, I am not a purist either! Use common sense. Use it every day! Stop listening to extremists. The middle road is well traveled for a reason. That said, it is wise to occasionally take the road less traveled.

5 Rob March 15, 2008 at 3:32 pm

Do I hear siren voices?
No doubt about it:
no weed infestation of any kind needs a chemical.
There are always alternatives.

6 admin March 15, 2008 at 3:41 pm

Rob, say more. What would you do instead in these particular situations? Sure there are always alternatives, but do they ALWAYS work?

7 Rob March 15, 2008 at 4:04 pm

My allotment has had a bad infestation of bindweed (convolvulus arvensis): I dug it out. I admit that this is hard work and I have to remain vigilant because a tiny section of the root left in the soil can become a vigorous plant very quickly, but I have not had to use weedkiller.

Couch grass (Elymus repens) is another persistent pest: once again the answer is to dig out.

I have also had success using blanket mulches of old carpet or thick black plastic sheeting. These stop light and have proved very effective in eradicating weeds.

I kill perennial weed roots by immersing in water – they become an excellent liquid feed after a few months.


8 admin March 15, 2008 at 4:42 pm

Rob, that was great. I don’t know if they’d work in my situation but I’d sure try them.
I’m so glad you found me because now I’ve found you and your wonderful blog. YOu may just be my male, English counterpart – which I hope is okay with you, given our lack of total agreement. Us sustainables can take a few punches, though.
Come on over to GardenRant, too. It’s a good bunch who disagree very agreeably, for the most part. Susan

9 Rob March 16, 2008 at 2:59 am

Nice one Susan.
Let’s work together!

10 Adrian March 17, 2008 at 12:01 pm

Bindweed in the Midwest is pernicious: I’ve been battling it for twenty years, finally gave up and every spring brush it with roundup where I find it growing (mostly up the chainlink fence behind the raspberries). I commend anyone who’s been able to dig it out (I do that also, where possible).

That being said, the rule of “appropriate use according to situation” applies: in limited amounts, only where absolutely necessary. Just like gas mowers–why not use a push mower if all you have is a small urban lot–and all the other unnecessisarily misused/overused products of modern technology and industrialization.

Also, layers of newspaper with mulch on top kills weeds and grass quite well.

11 Robin March 17, 2008 at 5:44 pm

I live in San Diego with a hill in back of me that basically wants to be a cliff-compacted sand. The only sensible way to remove the invasive grasses and dandelions that threaten my hill of natives after the rainy season is to cut them to the ground with shears, then apply Round-up. In three days they’re dead, and I haven’t disturbed the fragile hill by pulling them out. Even the native plant landscape designers here use the stuff. And the leftover detritus helps prevent erosion.

12 Andrew March 18, 2008 at 7:42 am

What about using layers of newspaper or cardboard as a kill mulch. Does this work? Will this kill off the soil biota?

13 Lisa Albert March 18, 2008 at 12:49 pm

A year or two ago, I received a sample of an organic herbicide that was mostly concentrated acetic acid (vinegar) and clove oil. It smelled great and seemed to work with varying results on two of my garden’s nemesis: cape fuchsia and Japanese anemone. Oh, I wish I’d never planted either! They have been much, much too happy and successful and have been impossible to dig out (and I’ve tried for years).

But I wondered as I used it, just how “safe” it was (tobacco is organic but it’s definitely not safe). Is this clove oil herbicide better (safer) than Round-up, a push, or worse? I wish I knew.

About a decade ago, I attended a conference on weed management sponsored by The Wetlands Conservancy, The Nature Conservancy and a few other organizations. One presenter explained the process her organization went through trying to eradicate non-native spartina grass from mud flats in the Puget Sound area. The grass was colonizing the area and eliminating habitat for a clam (I think that’s what it was). She and her crew were committed to finding a non-herbicide alternative but after many attempts and failures, they went with Round-up (or a facsimile that is “water-safe”, this is a decade ago and my memory of details is fuzzy). It was not an easy choice for them but they weighed the cost of losing the battle with spartina grass and the subsequent loss of habitat against the environmental consequences of using an inorganic herbicide and found the latter to be the better option. It was a point of contention and discussion. Which is the worse environmental evil: Round-up or the invasive invader?

Sorry for the long post.

14 Christine Migala March 18, 2008 at 3:16 pm

RoundUp is not active in the soil. The chemicals get bound up with the soil particles. It only works internally on living plant tissue (roots included).

Every pesticide has a lable on it and if you use the product you are under contract to use it according to the lable. The lable is the contract, so we’d all better read the labels.

15 Melinda March 18, 2008 at 8:20 pm

I read this a while back and it’s taken me several days to decide to leave a comment.

Two weeks ago we had an AWFUL AWFUL AWFUL experience with pesticides. I still have horrible rashes from it. Please do take a look at my post about it:

(if that doesn’t work, use this: )

We did approach the sprayers of the pesticide, and it was Roundup. I don’t know which Roundup, as there are many herbicide and insecticide varieties they make. But I do know that this isn’t an isolated incident. Several people have left comments and emailed me about their own similar experiences. Two people in my Master Gardener class had pets who died from exposure…

My answer would be that the better alternative is to do nothing rather than risk your health, the soil’s health, and the environment’s health. It’s not worth it for some weeds.

16 Susan Harris March 19, 2008 at 4:48 am

Andrew, I imagine any “kill” method would also kill the soil biota, as Jeff Lowenfels tells us that black plastic does so thoroughly.

17 Adrian March 21, 2008 at 8:42 am

Re newspaper and mulch: Newspaper and mulch form an organic layer and kill weeds by lack of light, not by concentrating the heat of the sun and preventing respiration or rain penetration as does black plastic. Why would soil organisms be negatively affected? One would think the decomposition of said organic layers would be to their benefit, as is the case with fallen leaves in forests.

18 Susan Harris March 21, 2008 at 8:50 am

Adrian,that makes perfect sense. Thanks!

19 Ali March 21, 2008 at 10:09 am

This is an interesting post. I’m a committed environmentalist and an organic gardener, yet I finally broke down and used Roundup last year to try and eliminate the invasive japanese knotweed. The kotweed was taking over my border of native shrubs, and marching relentlessly toward the back of my property where a vernal pool is located.

I tried digging it out, then covering with layers of newspaper and old carpet, cutting back ruthlessly any that survived, all to no avail. I researched extensively, followed the directions from Monsanto’s website, and was extremely careful. It worked. 90% of the knotweed died, and I will give it a second go this year.

Where I live, knotweed is a huge problem, colonizing wetlands and streambanks, and destroying native habitat. Judicious use of Roundup goes a long way toward saving these areas otherwise lost. No other effective strategy for its removal has been identified.

As several others have mentioned, appropriate use (in this case last resort use) spares us all from the perils of carelessly-used pesticides. The real problem is not this type of use. The problem is pervasive over use in big ag, and careless other users who don’t follow the label directions.

20 Kathy Jentz March 23, 2008 at 4:58 pm

I see Round Up as a LAST resort — I have it in my garden shed, but have not had to take it out all last year. I do not like the cavileer way it is sprayed in parks, schoolyards, etc. I think that every means possible should be used before it is employed. We cannot know the longtern effects. Remember how safe “DDT” was considered back in the day?

21 Mike Malterre March 23, 2008 at 5:46 pm

I have been searching for an alternative to chemicals and have had no luck. I have 1200 feet of ditch bank to keep clear (by law) and a 1/2 acre pond that fills with eurasian milfoil. I have had to use Reward and Cutrine on the pond as natural methods have failed. Burning the ditch was outlawed and I could never hold down a job and do it by hand. Any suggestions would be greatly appreciated. 10 acres is a lot to do by hand!

22 Jeff Lowenfels May 10, 2008 at 12:00 pm

It isn’t the Chemical in round up that kills the plant that is of concern….a danish study showed that the ‘inert’ ingredients do stick around in the soil and do get into the water system and are not good.

The idea that we can all just use a little, sometimes, and all will be fine is not a valid one…….

Let’s stop poisoning ourselves!


Jeff Lowenfels

23 Susan Harris May 12, 2008 at 5:36 pm

I just found this in a pamphlet about “Garden Maintenance for the Eco-Friendly Gardener” published by Green Springs Garden in VA, which does the best and most eco-gardening public education in the DC region. It calls Glyphosate “a relatively safe herbicide with minimal impact on the environment due to rapid breakdown and few effects on non-target species.” Around water they say to use a formulation without surfactant, like AquaMaster or Rodeo. Glyphosate is “commonly used to control perennial weeds and exotic invasive plants. Some perennials are very difficult to remove without herbicides.”

24 Paul May 27, 2008 at 2:54 pm

Great website. I am a avid gardener in the Atlanta area. I’ve found Roundup to be a very useful herbicide for specific purposes i.e. spot weed control on driveways,along edges and controlling poison ivy, etc.
None is ever applied to my vegetable garden as I try to be a organic as possible.

25 richard August 1, 2009 at 11:58 am

Our town citizen’s group maintains a nice preserve. One of the active members offered to apply Roundup to Poison Ivy. I opposed, saying that, although trouble to some, Poison Ivy is a native plant which has beneficial attributes for birds and wildlife.
I am opposed to using a herbicide that may also affect other plants and amphibians.
Could someone offer any strong arguments I can bring to our board should I find that they would accept the offer of herbicide treatment?

I offered to go in and prune egregious growths near paths if that would do the trick. (Now if they take me up on it,I’ll have to find the time to do this)

26 Betty April 8, 2010 at 7:09 pm

I need advice:
I wanted to have an organic vegetable garden, so I asked my gardener to dig up a small patch of lawn for me. 3 weeks ago he sprayed Roundup on the that area then 2 weeks ago he tilled the soil. My question is: How long should I wait before planting any vegetables in that space? Or should I even bother to plant? My grandchildren will eat the produce and I want it to be safe. Thanks.

27 Susan Harris April 8, 2010 at 7:48 pm

Betty, that’s an important question and I don’t know the answer. Keep Googling, though, and I recommend government websites for this purpose. USDA, EPA?

28 Tom April 19, 2010 at 7:45 pm


I would not hesitate to plant vegetables in a plot that had roundup applied to it 3 weeks ago. I would eat those vegetables and wouldn’t have a problem giving them to my kids. The Roundup (glyphosate) should have bound to the clay in the soil and won’t be taken up by the plants that you’re seeding.

But I don’t think “organic” is as big an endorsement of things as some people. I mean tobacco is organic, but I’m not going to let my kids have a cigarette or chewing tobacco.

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