Removing Invasives in Public Places

Hello Permies!

I've been thinking of ways to improve the natural state of the area I live in. Here on the California coast, a very prolific invasive species is Pampas grass. I see it all over the place - it especially flourishes on the side of freeways where no one is maintaining the land. I found some pampas grass in the woods, and decided to try reducing it. I cut off all the flowers from the plant and stored them in a bag to take home and dispose of. I then cut off all the green leaves from the plants I found as well - they're all so well established it probably won't kill them, but hopefully I can slow their growth before planting native species around them. I don't want to try pulling them out because their roots are quite deep and if they break it just leads to more grass. On one of them I found a baby pine tree growing - I made sure to trim all the pampas around it so it would get more light.

Any advice you can offer about effectively removing invasives would be helpful. I don't want to go spraying any herbicides or doing anything drastic.

Hey Malek,

So... You want to kill some plants... Not just any plants, but a hard to kill invasive perennial grass on steroids... Im no expert on Pampas grass, but I think I can get you pointed in a good direction. If you search online, you are going to find 2 different kinds of videos about Pampas Grass, how to care for it (propagate, prune, feed, etc) vs how to kill and remove it...

From what I have heard, the stuff is like mint and can come back from a small bit of root left in the soil... But... Lucky for us, you are not the type to give up either, and will keep going back to re-kill it again and again like a bad horror movie that Hollywood cant let go of. So get yer hockey mask on, grab yer favorite machete, and then set it down in the corner while you spend a few hours watching you tube videos. We’re not ready for that yet, we need a plan.

Get to know your foe, you want to know everything there is to know about caring for it, how to propagate it, when to prune it, feed it, nurture it, soil PH, etc. Those are the clues you need to kill it, to punish it, to weaken it, and eliminate it for good, (you need to understand it). Then watch the videos on how to kill it (and you will see all the mistakes people are making when they don’t know their foe).

Killing most plants is pretty easy, people without green thumbs do it all the time. But pampas grass doesn’t appear to be an easy kill. Fortunately, you know something those other folks don’t know... (you think I’m gonna say foe again, don’t ya?... Nope)... You know the secret of all plant life. Light, water, nutrients, without them, any and all plants die (many go to seed before they do, but they still die). You just need to figure out how to achieve this with the least effort in ratio to the highest chance of success (within the confines of the tools and resources you have available to you).

From my understanding, pampas grass tends to laugh at most herbicides, and herbicides do far more harm than good anyway. Fire is out of the question (when you run across videos of people burning pampas grass you’ll see how ferocious it can burn, and if it catches when it’s still green the smoke they emit is insane, (I’ve seen that in person and it was not good). And it’s a grass, so fire isn’t going to kill the roots. The blades are way too sharp for dogs to eat, so drowning it in bacon grease isn’t going to work (that’s a lame joke, btw).

Perhaps someone with a more experience and knowledge might jump in and divulge a secret/trick, but I’m not gonna bank on that. I recommend you do some research/learning to develop and refine your approach (watch some videos on YouTube)... Sure, we can jump into the oldies and generic kill methods, but you might stumble onto something better when you do your research and that might make it really easy or at least give you a better idea of how to tell if you beat it.

Worst case, you can chop it down to the ground and cover it with anything that blocks light and repeat until it stops coming back (that could take a couple years and might be hard work).

Regardless, I wish you luck!

Thanks for the support Paul.

Here's what I've come up with in terms of a gameplan: I've got a bunch of native plant seed mix from Northwest Meadowscapes. I'm going to make seed bombs out of it. I'm going to go to places where there's Pampas, and spread the seed bombs around the Pampas. Then, I'll chop the Pampas down to the root, and mulch with the clippings directly over the remaining plant. This is for the larger ones - hopefully the smaller ones I can pull out of the ground before adding more seed.

Another issue I'm considering is what to do with the flowers. I tried burning some but it just makes way too much smoke. One idea I had is to try growing winecaps with them. I already have a tub of woodchips that's had wine caps simmering for a few months, so I layered them into a 5 gallon pot with a bunch of Pampas flowers I collected today. Hopefully I get some good mushrooms out of it, or maybe it'll just be the knowledge of what will happen. One thing I'm worried about is if the wine caps successfully grow onto the pampas, the resulting mushroom castings/soil will then sprout pampas from whatever I add it to. One problem at a time!

The flower heads might be rendered sterile via boiling water.
You could feed it to chickens after that.
I would probably want to make the seed head and tge grass itself into charcoal via a TLUD type retort.

Last summer I tried a tactic for dealing with noxious weed seedheads that I didn't want to dispose of any other way. I followed those things I've seen online, about making a rotten weed tea and using it as a soluble fertilizer. I packed the aggressive weeds in a bucket, filled it with water, put a lid on it, and left it standing out in the sun. It smelled more like vomit than anything I've dealt with in the compost before. Without the lid, the weed floated up above the liquid, and it attracted yucky little flies. After it stank and the liquid was black, I strained it into another bucket, and added more weeds and more water and left it again. To be honest I can't remember what I did with the detritus at the very end. I don't know if any seeds could survive and be viable after that treatment, but I suppose it's possible.

My most noxious weed two years ago was puncturevine, aka goatshead thorn, Tribulis terrestris. That year, I collected all the puncturevines in my land, and I actually pressure cooked them, and then composted them. I had almost none appearing last summer, so I think the seeds are vulnerable and short lived.

Everyone has given you some great incite.

My first thought when I saw your blue bag is that any seed head in that bag might fall out and start growing somewhere else, especially at your home.

Maybe a ziplock bag put into the trash might prevent that from happening. Or burn the bag unopened.

I am fighting thistle on my property this year with a vengeance to no avail. I have 40 acres for it to grow anywhere it wants but it decided to grow where I walk the dog.

I don't want to be the stick in the mud here, but I keep thinking of all the things I've read about invasives in permaculture books like Gaia's Garden and the one that was given away not too long ago here on Permies, Building a Better World in Your Backyard--that they're not the bad guys a lot of people think they are.

Looking at Malek's photos, I was caught by the one with the baby pine tree. I couldn't stop looking at it--why the heck is it growing there? Did it germinate before the Pampas, or after? Looks like after, as Pampas clumps take around 3-5 years to get that established. If that seed did germinate right there all up in the Pampas grass's business, why would it do so?

You're on the California Coast, where it can be salty, windy, and pretty dry--those are some harsh conditions for a little plant. Maybe the Pampas is being a protector in this case--it's very good at withstanding salty air and wind. And yes, the grass roots can grow to be more than 10 feet long--at first you would think that that would be bad for the little pine tree. But then again, it gets dry on the coast, and any ground with roots in it is retaining water. Furthermore, baby pine tree taproots grow to be pretty long relatively quickly--I've read the range is anywhere from 5 to 20 feet. Larger mature pine trees have a taproot anywhere from 35 to 75 feet long!

And after 10-15 years, the Pampas grass would die, leaving an established pine tree to grow for who knows how long. You may have just stumbled on a truly excellent way to grow trees along the coast...

Rebecca Norman wrote: My most noxious weed two years ago was puncturevine, aka goatshead thorn, Tribulis terrestris. That year, I collected all the puncturevines in my land, and I actually pressure cooked them, and then composted them. I had almost none appearing last summer, so I think the seeds are vulnerable and short lived.

I’ve lost many bicycle tires to goatshead thorns... And stepped on a few with thin soled sandals and shoes... You have my sympathy with that cursed weed.

Composting will kill seeds, but only if it gets hot (like any proper compost pile should).

The only plants I know that would strangle the life out of pampas grass are other invasives, and trading one problem for another is never a good idea. But everything has a weakness, perhaps the weakness of another invasive could be easier to exploit. Wisteria will strangle the living hell out of anything, including a giant clump of pampas grass. I’ve seen wisteria tear apart 4x6 posts on arbors like they were wet tissues. I’ve seen wisteria strangle massive oak trees and shade out everything under them. But wisteria isn’t too hard to kill as long as you keep on it (it also has pretty flowers)... I’m not saying you should plant wisteria next to it, I’m just trying to help you consider unconventional options, think outside the box kinda stuff.

Anyway... Good luck!

I appreciate the ideas. I'm rather limited in terms of space to work with but maybe I can try doing the sealed bucket thing. It does seem like burning it into charcoal is the most effective method, but I don't have space to build a kiln and I don't know anyone who owns one. And I'm hesitant to boil it in case it makes my apartment smell terrible....

Anne - it's not obvious from the photo, but the bag has a zipper on it.

Erin, I agree with you that some plants are considered invasive when they shouldn't be. But I think it's important to know the history of pampas grass in this area. It is well known for crowding out native plants and taking over meadows. It has no use for the local fauna - deer can't eat it because of the sharp edges on the leaves, and pollinators don't get anything from it. There have been multiple restoration efforts by various government agencies to remove it from the coast and plant native species that provide food sources for local animals, but the pampas is a tough opponent.

I'll give you some examples with google street view. Here's a meadow of pampas. There are some pine trees around the border, and some low lying grasses around, but other than that it's all pampas. Not much room for other life. I imagine you were thinking of a situation like these pampas grasses, where they're across the street from the ocean growing on bare dirt. I'm less concerned with these ones since there's nothing there from them to crowd out, but given how aggressively it spreads I would still want to remove them. It might die in 10-15 years, but in that time it will have reproduced many times over.

I'd also like to note that usually the San Mateo parks conservancy manages volunteers removing weeds such as pampas in various parks, but due to COVID they are not doing any volunteer programmes right now.

I think a good example of an "invasive" like what you were thinking of is poison oak. People don't like it because it causes rashes, but deer can eat it and birds love the berries it produces, so I'm okay with it.

Ironically, I think that pine tree will spread just fine without pampas grass. Pacifica was managed by Ohlone tribes for thousands of years, then farmed according to traditional European agriculture methods for a long time. A lot of the forest that was removed before was replaced with Jeffrey pines when the land was left alone - it's very good at spreading itself. If it wasn't, it probably wouldn't be germinating in the middle of a pampas grass cluster!


Study on invasive pampas grass in California from 1992

Malek Ascha wrote:Then, I'll chop the Pampas down to the root, and mulch with the clippings directly over the remaining plant.

I don’t recommend this... Sounds like the perfect environment for the roots to sprout hundreds of fresh young shoots...

But if you chop it to the root, cover it in layers of cardboard (instead of nasty plastic weed fabric), add some dirt on top and plant some seeds and then mulch those with the pampas clippings. Hopefully the new plants can sprout and grow enough to keep the pampas root from coming back to life (the cardboard should buy some time for the seeds to grow and the pampas mulch should keep the deer off it for bit).

Timing is important. If you chop the pampas in the fall then it should struggle going into winter and that alone might kill it. Some of the new native seeds might germinate early but most will wait for spring. Late spring is when I would plan to go back and check on it to see who is winning and possibly help anything non pampas if needed.

Good Luck!

Cardboard is an excellent idea, Paul! A lot of what I've been seeing lines up with what you're saying vis a vis timing - native wildflower do best when sown in autumn. I'll probably still plant some stuff in areas where I know not much else is growing just to see what happens.

If I'm going to wait until winter to plant things on it, I still want to be doing things that will weaken the grass leading up to that time. So, I'll keep collecting flowers, as well as trying to pull out the smaller pampas plants.

Do you think it would be beneficial to just cut it to the roots right now? When I'm planting things in the fall I would then cut it to the roots again before sheet mulching as you've suggested.

I found a pampas specimen that supports your idea that it'll just grow through mulch. It's a bit hard to see in the photo, but it looks like someone dumped a load of wood chips in the middle of this field, and a GIANT pampas plant sprouted out of it, doing extra well thanks to the lack of immediate competition. So I definitely want to avoid a scenario like that.

Malek Ascha wrote: Do you think it would be beneficial to just cut it to the roots right now? When I'm planting things in the fall I would then cut it to the roots again before sheet mulching as you've suggested.

Sure... Anything you can do to continually weaken the plant is going to slow it down and benefit your goal. You could try dissolving a bunch of baking soda in water and dumping some on a pampas clump to see what it does. You could hit a different one with straight vinegar to see what that does. You could chop one down and invert a 55 gallon drum over it or an old tarp with rocks to weight it down, any kind of thick plastic sheeting to see if you can get the sun to cook it, etc. You experiment around enough and you are likely to figure out various things it doesn't like, and anything that makes it struggle is your friend... You stay on any plant long enough, and keep it from photosynthesizing, it will eventually die. And who knows, you might stumble upon a lethal combination that makes it easy and cheap to kill Pampas Grass, and if you do, there are a lot of people (including government/parks and rec/fire control/etc) who will herald you as a hero if you share that info with them.

Good Luck!

For what it's worth, goats will eat it. I don't expect you to buy a herd, but you might be able to rent a herd. In the Midwest, Departments of Transportation have been using goat herds to eat up all the Kudzu (Pueraria montana).
This article is from NY but it's the same issue: https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb1167286.pdf  The DOT does not own goats, they rent time with them from the goat owner, who also brings the materials to enclose the area in which the goats will eat. DOT enforces lane closures and speed limits on the areas where the goats are "working", the same as if there was construction on the road.

Goats are friendly, the babies are cute and perhaps they are not so difficult to maintain (IDK -- I only know goats from when I was a teenager and my nephew was born with an allergy to cow's milk. I loved going to the tiny farm and hanging out with the mom and dad and baby goats. I didn't care if they nibbled at my coat or ate my gloves.).  In the DOT, the herd is managed by walling off an area next to the highway, the goats are released into the area and eat, basically everything. Then more fences (fences are too strong a word) are built around the next door area, the goats are allowed into the new area, the fences come down in the old area and are reinstalled at the next, next area.

I don't expect that you can manage the goats to only eat pampas grass, but if you can get one or two to concentrate on one giant clump, your work will be greatly reduced. They will eat that grass down to the nubby stub -- far shorter than you could cut it down.

Also, what about human pee? I know that I can take out a tree stump if I drill a hole in it and have a man friend pee in the hole. Would spraying or otherwise ah, "watering the pampas stumps with human pee" kill the root?  Gross for a city slicker like me, but effective. It was the last thing I had in my arsenal to kill a tree stump that grew up at the fence line on my property n suburban KC. And, it was what worked.

Good luck!! You're doing the right thing.

Pampas grass grows in NZ too. I use my digger to uproot them. If you use a sharp spade you can remove them by cutting the roots just below ground level. Just leave where you remove as they will rot away.
You can also chop and drop, they produce good mulch.

Just did a quick search on the New South Wales DPI website.  They caution that the seeds will blow up to 25 Km (15.5 miles)

"To tackle pampas grass:

   check for seedlings across your property as seeds can spread up to 25 km from a parent plant.
   control seedlings as soon as they appear control plants before they set seed as plants can produce up to 100,000 seeds per flower head
   Physical removal is the preferred control method.

Avoid controlling pampas grass in summer to protect native wildlife. In summer, pampas grass can be an important shelter. Snakes such as the diamond python may lay eggs in the grass clumps." https://weeds.dpi.nsw.gov.au/Weeds/Details/100

My parents had a Pampas grass and used to chop the seed heads off it.  The roots will go down 3.5 M (12 feet) and it has rhizomes that spread out from the plant so it is more than just dig it out.  To get that sucker out do it before it gets too big or you will need some serious machinery.
It is unlikely that the plant will be removed without continuous hand removal.  One thing though, it hates shade.  It does have some drought tolerance.

Riaan van Schalkwyk wrote:Pampas grass grows in NZ too. I use my digger to uproot them. If you use a sharp spade you can remove them by cutting the roots just below ground level. Just leave where you remove as they will rot away.
You can also chop and drop, they produce good mulch.

New Zealand has 4 native types that are less invasive than the South American species.  But still can be a pest.  The plant has hybridised to develop hermaphrodite seed that does not need pollination so it is important to cut the seed heads before the seed is mature.

About 15 years ago my wife bought a pampas grass plant for the corner of our front yard.  Pampas grass is considered ornamental here in Montana.

It grew very well !!  Very large and looked wonderful there.  Built a small bed of rocks around it.  It got big and had little ones.  lol

One winter the neighbor hit it hard with the snowplow.  Next spring it did not look as pretty as before, but came back full by end of summer.

Many dogs used it as a fire hydrant for those years.

I would say it was in-destructable.  

Sold the place two years ago.  One of my sons went by last summer and said it was bigger than ever.  

I would caution against any blanket statements that "invasive exotic plants are not that bad". Privet, Nandina, English ivy and kudzu are a scourge on the earth here in the Southeast. Come to Georgia and see for yourself. Horticultural grade vinegar with dish soap as a surfactant is respected for its ability to kill weeds (and careless users), but it breaks down into harmless byproducts. Smart growers wear goggles and gloves and usually survive the weed kill.

Plant tree seeds in it. Apple, peach, pear, apricot, plum, pine. Anything that works. Try comfrey. Try chestnut and walnut (aleopathic!). Try black locust. Try raspberry, salmon berry, blackberry, mulberry. Try oak. Just bomb the things with seeds until you hit on something that the pampas grass facilitates. Don’t overlook the feedback of the pine tree growing there. If you find a list of species that is both friendly to your native species and facilitated by the pampas grass, you could actually use it to facilitate your native-spreading project. What if you find a bare, arid field and want to spread native plants on it, but the ground is too desiccated, and swales are just too much work, or the land is to steep for them? You could put plugs of pampas grass together on contour, plant your list of next-succession anti-pampas plants and trees in the pampas the next season, and after those get going, plant your natives all through it. The best thing about this system is that it would spread by itself. Remember that everything is an asset. If you do this everywhere, the pampas will go away, and it’ll have left a wonderful legacy behind it.

Literature Review

Often times in research to solve a problem one of the first important steps is to find and document what studies, observations and in general writings about a subject. Researchers call it a literature review. From my experience you first try to find information that is available, document it as a list including access to the information - if possible obtain copies. Then read and analyze what is said about the subject. Finally each of the resources should be summarized with comments and observations.

Here just a 15 minute quick look just using the keyword phrase “literature review pampas grass”. I got tired of the many pages available in the browser search so I stopped. But think about if you got even more specific with the key word search and used phrase Bibliography of Research into invasive Pampas Grass, or articles related to controlling Pampas Grass. You get the picture.

One interesting observation I have from just this little exercise is a pretty amazing trend in e-commerce offers for Pampas Grass as a design and garden feature. It tends to conflict with the problem as an invasive bad actor.

Review of control methods for pampas grasses in New Zealand

https://dcon01mstr0c21wprod.azurewebsites.net/globalassets/documents/science-and-technical/sfc165.pdf

Weed Risk Assessment for Cortaderia selloana (Schult. & Schult. f.) Asch. & Graebn. (Poaceae) – Pampas grass

https://www.austintexas.gov/sites/default/files/files/Watershed/growgreen/2017LPT/day-one/GGLPT-Day-One-Landel-Handout-Pampas-grass-Weed-Risk-Assessment.pdf

Growth and Resource Use of the Invasive Grass, Pampasgrass (Cortaderia selloana), in Response to Nitrogen and Water Availability

https://www.researchgate.net/publication/260140748_Growth_and_Resource_Use_of_the_Invasive_Grass_Pampasgrass_Cortaderia_selloana_in_Response_to_Nitrogen_and_Water_Availability

IRRIGATION EFFECTS ON GROWTH AND VISUAL QUALITY OF THREE ORNAMENTAL GRASS SPECIES

https://mountainscholar.org/bitstream/handle/10217/82634/Rozum_colostate_0053N_12297.pdf?sequence=1

Literature Useful to the Study of Florida Plants Grasses (Poaceae)

https://www.floridamuseum.ufl.edu/herbarium/bib/bibgrass.htm

Weed Risk Assessment for Cortaderia selloana (Schult. & Schult. f.) Asch. & Graebn. (Poaceae) – Pampas grass

https://www.aphis.usda.gov/plant_health/plant_pest_info/weeds/downloads/wra/Cortaderia_selloana_WRA.pdf

Pampas Grass | UGA Cooperative Extension

https://extension.uga.edu/publications/detail.html?number=C983&title=Pampas%20Grass

How Dried Pampas Grass Became Instagram’s Favorite Design Trend

https://www.mydomaine.com/dried-pampas-grass-4797013

Campaign launched against pampas grass

https://www.sandiegouniontribune.com/sdut-1mc3pampas233036-campaign-launched-against-pampas--2009may03-htmlstory.html


Ornamental Grasses and Sedges as New Crops

https://hort.purdue.edu/newcrop/ncnu02/v5-473.html


And then there is this

PAMPAS GRASS SALES DROP DUE TO SWINGING CONNOTATIONS

https://www.independent.co.uk/life-style/love-sex/pampas-grass-sales-swinging-sex-connotations-seventies-houses-front-garden-a7764796.html

Weeds make me shake my head.  At work, I'm the regulatory specialist and geologist of an energy company.  In no way at all do I know anything about any weeds without a little research when needed.  In our closed southern Wyoming fields, the BLM wants me to kill the only thing that wants to grow on the moving sand dune, which they expect me to re-seed for the third time with their chosen seed mixture in an effort to choke it out (huge field, $30k of wasted time and resources each round). It's a nasty weed that animals don't like and is actually deadly in large amounts, called halogeton. To me it even sounds like a Transformer name or something. Godzilla meets Halogeton.  In our northeast Wyoming fields, I am supposed to kill EVERY weed, as their reclamation process looks much different.  Weeds:  I am killing in the north what I am planting in the south, but so be it.  Some days it makes me laugh.  The re-seed process - that I know will be futile on a moving sand dune in the Red Desert, where anything green is gobbled up by the cattle on the Fed lease and the wild horses, hares, etc- has been attempted since the first invasion of Halogeton in the 20s or 30s- I'm pretty sure will never get that reclamation process finalized.  And the evil weed was brought via railway, bird poop, truck tires, etc. but the lowly salt bush is the only thing that is allowed to be there.  Even planted en masse, salt bush doesn't stand a prayer against the 'evil' halogeton.  Our efforts will probably be added to yet another PhD thesis some place.  We have filed bankruptcy.  

Here at home, I was out of money and had no greens left to eat last summer between paychecks, so I went out in the yard that my dogs are not in, and picked some plantain.  I had missed most of the tender shoots but ate some leaves and what I could find and once again, that made me shake my head.  Only 2 years prior I had "weed and feeded" that lawn to keep up with the neighborhood, but knowing the water table was only a foot below ground, I quit that baloney.  Another head shaking moment was going out to the back yard where my 3 dogs and 9 chickens, plus various wild birds live, and the plantain is more abundant in the animals' favorite poop places.  Ah, Nature is amazing.  

I dug up some plantain and added it to my dandelion bed.  My neighbors hate my dandelion bed.  But they love my chicken eggs so they tolerate me.  Some weeds, like the pampas grass nurse crop to the little pine tree may have a place in time for a specific reason....figuring that out is more my passion than how to kill it, but I have to do that too on occasion  Like when I planted horseradish near a previous house and had to hire an excavator to dig it up where it went under the perimeter wall foundation of my garage and cracked the cement.  I plant horse radish in pots now.  

BUT if for some reason you decide the best course of action really is to get rid of the grass, you’ll have to understand that it is not the disease, it is a symptom. Usually a weed is a symptom of soil imbalances. You could take soil samples from near (about three feet away is a good guess) the clumps, and perhaps also from right next to the clumps. Take notes on any aspect of the soil samples that the labs might not measure or be able to measure, like structure, compaction, moisture content, organic matter content, aerobic or anaerobic and the like, and send the samples to a lab that doesn’t use a corrosive chemical to test, because the gentler chemicals will more closely mimic the bioavailability of the minerals to the plants. Once you get the data back, look for patterns in the soil imbalances, and remediate them, perhaps with native forbs and nutrient accumulators or something.

Have you considered selling it? It's very popular as a decor item, which I see was mentioned briefly.

If you're comfortable working with bleach, I wonder if you could bleach them to sterilize and then dye them a fun colour. Light pink is trendy these days. And that way you would have to worry about sending invasive seeds all around the county!!
I wonder if that would work, and of they'd hold up to it. But I figure if you process as many of the seed heads as possible, that's a good start to preventing spread! Sounds like they're a hell to get rid of.

Just a thought! Check out some of the online pampass grass stores. I had it in my head last year as we have a couple local ornamental grasses that look similar in style, and grow by roadsides.

Well, Paul is absolutely right: Look at what the plant needs to thrive and try to remove all the elements that allow it to thrive. Don't neglect the Ph. I do not know what the requirement is for that plant In WI, we think of it as an ornamental![It is not an invasive here]. If it needs alkaline soil, pour vinegar on the plant. If it needs an acid soil, counter with things that will sweeten the soil. Although I read that it thrives in a variety of soils and takes salt spray and drought really well. :-(
In the meantime if the plant is accessible with a lawnmower, keep mowing it to extinction: Roots get stronger when they are fed by a lot of green leaves. Consistently mowing very short diminishes the strength of the plant.
Thinking outside the box, and I fear invoking big brother because they may suggest harmful chemicals, you might want to probe how your local elected officials feel about pampa grass. You may want to point out that when it dries, it becomes a fire hazard? and since your neighbors may also have that annoying plant in abundance, would they join you in your efforts? If you and all your neighbors join in the effort, you would at least have less seeds? The plant itself lives 10-15 years and from seed germination to maturity [ability to spread by seed], 2-4 yrs. that may be its Achille's heel: Removing the very young plants as soon as you can identify them would in 10-15 years eradicate them, if you can keep preventing them from seeding, of course.
https://www.hunker.com/13427027/how-fast-does-pampas-grass-grow
Another ally in your fight might be dog owners as this plant is poisonous to dogs when green. [Diarrhea, coma, death]
https://www.cuteness.com/article/ornamental-grasses-poisonous-dogs

Courage!

I've found my serrated old breadknife to be my favourite weed-killer lately, as I'm attempting to do no-dig on some serious couch grass/bindweed beds. I cut plants off just under the soil surface, repeatedly, and keep it covered with thick cardboard in-between times.  I think over time it will exhaust the rhizome/tuber/root#s energy reserves and I can start planting having not disturbed the soil at all.

I'm not an expert and I've never tried this method before, but I remember watching a video on the use of pigs to prepare an area for growing food. In the video, the farmer demonstrates that with some encouragement, the pigs will dig up the roots of invasive quackgrass and possibly also creeping thistle (Cirsium arvense) and non-woody kudzu roots (Pueraria montana). Yhe first stage would be to have goats mow down the larger plants in the area. Once the large vegetation has been cleared, then the pigs can go in and dig up the plant roots. Here is a relevant video that I found on YouTube:
https://m.youtube.com/watch?v=BQreamkkafg

One faster method to kill any plant is to pour boiling water over it.    Pampus grass, I would think needs to be cut down to the ground and the roots left alone.   Then pour two or three gallons of boiling water over the base slowly.   I love the idea of putting the seedy tops in a bucket of water and let them sit in the sun for a week.
I myself am a very lazy gardener.

Wow... This one kinda blew up a bit...

I think a lot of folks are confused about this. There are many different types of pampas grass in the world. The type growing on the California coast gets huge and tall very fast, with razor sharp blades that deer nor goats will touch (And the place is crawling with deer that will eat almost anything yet leave the pampas grass alone).

The winds are very strong on the California coast, which spreads the seeds far and wide. This invasion is not a “symptom” of soil condition issues. This is an incredibly tough grass that is drought tolerant and can take high winds and being drenched with salt water. It grows in any and all soil types and is very good at reproduction. It is taking over the land and it’s not a food source for anything. It’s an invasive species and it is also a big fire hazard. It can serve as shelter for some snakes of mice, but there are plenty of other shelters all over.

While the plumes (flowers) are attractive, and overall the plant would be great on the coast were it not so invasive (if it only stayed where it was planted). So it all needs to be removed and all the experts agree, and all the government agencies are actively working to remove it, and they encourage all residents to do the same.

Hope that helps clear it up a little better. And if you have any relevant experience or ideas, please share any tips or tricks or tribal knowledge on how to get rid of or weaken this very hard to kill “monster grass”.

Thank you

Myron, I'm really liking your idea of planting various tree seeds in among the pampas roots and seeing what manages to sprout. It could bear some useful info, plus the eventual shade from a tree would prevent the pampas from growing. Time to start seed collecting!

Erin also sent me a PM elaborating on her position, and she raised a similar point to you - the pampas grass is truly thriving in areas where the soil/ecology was disturbed by human activity. So, in a sense, it's just moving into areas where nothing else happened to be growing - maybe if logging companies got into the habit of throwing down cover crop seeds after cutting down trees, this would be less of an issue!

I don't think we'll ever be in a situation where we use pampas grass intentionally to begin succession. It's doing a fine job of spreading itself to those places anyways!

Another issue I'm thinking about is dealing with pampas grass growing on extreme slopes (see example streetview). In this photo, we see a whole lot of pampas grass growing on a steep hillside, while next to it on another side of the hill is a more diverse set of bushes/grasses. Given our discussion about pampas as a pioneer, I don't think I should just go pull it out and hope for the best. But in general, replacing it with plants that can provide food for pollinators and other animals is the goal. The example I gave is a bit extreme since it's the side of a freeway with zero shoulder, but I've found similar slopes with trees on them that have tons of pampas growing around.

So I guess my question is, what beneficial plants for local wildlife will do well on a steep slope?

Malek Ascha wrote:Myron, I'm really liking your idea of planting various tree seeds in among the pampas roots and seeing what manages to sprout. It could bear some useful info, plus the eventual shade from a tree would prevent the pampas from growing. Time to start seed collecting!

Erin also sent me a PM elaborating on her position, and she raised a similar point to you - the pampas grass is truly thriving in areas where the soil/ecology was disturbed by human activity. So, in a sense, it's just moving into areas where nothing else happened to be growing - maybe if logging companies got into the habit of throwing down cover crop seeds after cutting down trees, this would be less of an issue!

I don't think we'll ever be in a situation where we use pampas grass intentionally to begin succession. It's doing a fine job of spreading itself to those places anyways!

Another issue I'm thinking about is dealing with pampas grass growing on extreme slopes (see example streetview). In this photo, we see a whole lot of pampas grass growing on a steep hillside, while next to it on another side of the hill is a more diverse set of bushes/grasses. Given our discussion about pampas as a pioneer, I don't think I should just go pull it out and hope for the best. But in general, replacing it with plants that can provide food for pollinators and other animals is the goal. The example I gave is a bit extreme since it's the side of a freeway with zero shoulder, but I've found similar slopes with trees on them that have tons of pampas growing around.

So I guess my question is, what beneficial plants for local wildlife will do well on a steep slope?

Well, I can't answer that off the top of my head, but I should think that if pampas grass creates a better water condition, then you need to pattern for wind, mostly. if there are no high winds, I wouldn't worry about it, and I wold just do tests until I hit on something that works really well. Seaberry comes to mind. This was exactly the kind of situation I was thinking of when I was talking about using the pampas for water infiltration.

Okay, so I just took a close look at those conifers along the road side, and it looks like they have nuts growing on them. That's a start. Can you find out what soil conditions these specific conifers like, what soil conditions they create, what plants like similar conditions and what plants like the conditions it creates? You could create a wildlife guild centered around these trees and pampas. there is the potential for a healthy ecosystem here, it just wants a little diversity injected.

Interesting! here with wet mild winters it never seems to reproduce from seed. It is a popular ornamental and propagated by division.  I had to move the one on my farm and it took digging a 3 foot circle 3 feet down to get it out. The seed plume is attractive in fall and early winter but becomes thread bare by spring. Maybe the torrential rains that blow up here from Hawaii will shift further south with climate change and solve your problem.  

Hans Quistorff wrote:Interesting! here with wet mild winters it never seems to reproduce from seed. It is a popular ornamental and propagated by division.  I had to move the one on my farm and it took digging a 3 foot circle 3 feet down to get it out. The seed plume is attractive in fall and early winter but becomes thread bare by spring. Maybe the torrential rains that blow up here from Hawaii will shift further south with climate change and solve your problem.  

Is your plant definitely female?  The male plants here on Australia have equally impressive blooms.  The propagators, to my reading, have managed to hybridise a sterile variety.  You might be on a money-spinner for large potted grasses as features.  Not surprised about the size of the hole.  How are you using your plant on your farm? As a feature of windbreak?

Paul, Malek, et al, you may have already tried this, but I just read that using dry ice may be the best way to eliminate that evil knife-edged weed.  I remember it well when I lived in Santa Cruz for college.  The short paper in the link says that they tried 4 ways to eradicate and dry ice was the best.  If the link doesn't open let me know.  It is pretty straight forward if you have access to dry ice.  Or liquid nitrogen...lol
 csef.usc.edu/History/2009/Projects/J2301.pdf

Linda Haven wrote:One faster method to kill any plant is to pour boiling water over it.  

I agree this will work but the amount of fossil fuel needed to get the job done is unrealistic to me. If anyone out there can build some kind of Arduino contraption running on two semi-circular rails which keeps a largish Fresnel lens focusing the Sun's rays unto one clump each day, that would be more environmentally friendly as well as not hurting the soil microbiome{That clump produces net oxygen and boiling water adds to your carbon footprint.}. Sort of like a Lockheed AC-130 gunship but using light instead of bullets. You move it unto another clump the next day.

Malek Ascha wrote:planting various tree seeds in among the pampas roots and seeing what manages to sprout. It could bear some useful info, plus the eventual shade from a tree would prevent the pampas from growing.  

If I recall correctly, the gorse infestation mentioned was only a stepping stone on nature's path to restoring the
native flora specific to that region and microbiome. Maybe it is the same for the pampas. If everyone steps back
we might see what the indigenous habitat would have been like. Just a thought. It might have been Jeffrey Smith
who related an anecdote about a corn species which a displaced North American Indian tribe took with them
that was in danger of growing extinct as it did poorly until it was brought back and planted in its original land.

Remelle Burton wrote:Paul, Malek, et al, you may have already tried this, but I just read that using dry ice may be the best way to eliminate that evil knife-edged weed.  I remember it well when I lived in Santa Cruz for college.  The short paper in the link says that they tried 4 ways to eradicate and dry ice was the best.  If the link doesn't open let me know.  It is pretty straight forward if you have access to dry ice.  Or liquid nitrogen...lol
 csef.usc.edu/History/2009/Projects/J2301.pdf

Very cool idea, thank you for sharing that. It doesn’t mention the amount of dry ice, but I doubt it would take much if used on a cold dry winters day. Good outside of the box thinking.

Paul Fookes wrote:

Hans Quistorff wrote:Interesting! here with wet mild winters it never seems to reproduce from seed. It is a popular ornamental and propagated by division.  I had to move the one on my farm and it took digging a 3 foot circle 3 feet down to get it out. The seed plume is attractive in fall and early winter but becomes thread bare by spring. Maybe the torrential rains that blow up here from Hawaii will shift further south with climate change and solve your problem.  

Is your plant definitely female?  The male plants here on Australia have equally impressive blooms.  The propagators, to my reading, have managed to hybridise a sterile variety.  You might be on a money-spinner for large potted grasses as features.  Not surprised about the size of the hole.  How are you using your plant on your farm? As a feature of windbreak?

Apparently the females are illegal in Washington state but the males are propagated by division and sold freely for decorative purposes. I just put it beside the driveway to make a transition statement between zone two and zone one. My Google search revealed it is an invasive problem in California and has escaped in Oregon so if one chooses to use it in their landscape, do not import seeds or wild plants.

I went out to look for more Pampas grass (which I've learned is actually Cortaderia jubata). I brought with me a native prairie seed mix from Northwest Meadowscapes, that I mixed with clay and compost. I noticed a few patterns in the way it was growing.

I mentioned before I found a pile of wood chips with a big pampas plant growing in it. I checked how deep the wood chip bed was and it seemed to be at least 6 inches. I cut back some of the leaves close to the base and tried seeing how it was growing - the roots were literally reaching through the wood chips. There were a few other plants starting to sprout out of the wood chips as well. I've included photos of some of them. In general, there are random piles of wood chips all over the place. Whenever the city workers trim back the growth near roads, they just pile up all the detritus and call it a day. I'm wondering if I should inoculate it with some mushroom spawn, but I'm not sure.

In general there are a few stages of growth I've identified for patches of pampas grass. Areas that have been recently disturbed, either through dumping of mulch or driving in dirt (based on the tracks someone was doing donuts) host a lot of smaller pampas plants. They grow fast on disturbed earth! I also found that within meadows full of native grasses, there would be one or two pampas plants that were at least 4 years old. So it seems that when the soil is disturbed, the pampas moves in and gets slowly replaced over time, with some plants getting big enough to survive long term. I was tempted to go trim them, but that would involve walking through all the lovely meadow plants and I didn't want to trample any.

On slopes and in shady areas, the pampas grass is doing quite well. It seems that the pampas grass grows faster than the other shade plants in the area. And it dominates the slopes. I'll need to get some shady seed mix - this one from larner seeds should do the trick - suggestions are welcome! I'm not sure how to plant on a slope in such a way that it won't get washed away. I can't do any major earthworks, because it is permies, city owned land.

I also found a few instances of plants growing within/near a pampas cluster. One such plant was a treelike plant with yellow flowers seemingly in direct competition with the pampas plant - it was reaching ever higher to outpace the pampas. I trimmed the pampas and put the mulch directly on it to encourage the growth of the tree. Another plant had purple flowers and I found a cluster of pampas plants, each of which had this purple flowered plant growing in it. I trimmed one pampas plant, thinking I was helping, only to find that it was actually climbing up the pampas leaves for support! I felt bad, but it gave the opportunity to experiment. I left one of them completely untrimmed, and on another I trimmed all the leaves that weren't directly supporting the purple flower plant. Between those and the one where I trimmed all the leaves, I'm interested to see which does best.

It took a while to find pampas that was growing in bare dirt - a lot of it had small groundcover flower growing about. But I found a row of pampas plants next to the trail that were relatively bare, and didn't seem like someone would drive on them anytime soon. I trimmed the plants and cleared the areas in between them, then spread the seed I had brought in those spaces. I found that there was a lot of roots in the soil between the plants, interested to see if the seeds can grow through it. I stomped on it after for good measure. I put all the clippings on the pampas plants themselves. I'm interested to see how it works out - I know that here in California with the dry summer, winter plantings are more successful. But I just want to see what happens!

My understanding has changed from when I first posted. I originally thought I would need to just remove the pampas, throw down some native seeds, and be good. But I like the idea of encouraging the plants that manage to start growing in pampas clusters through chop and drop. In general I want to try to just fill in the cracks to encourage productivity - planting lots of seeds in/around pampas clusters and trimming them to create mulch. I don't think smothering the pampas plant with mulch will actually work that well, because the older plants I saw had years worth of dead leaves piled on top of them from lack of grazing/trimming. The pampas is just the strongest opportunist in the area - my approach will be giving the other plants a leg up so they can compete. Plus their roots are so strong, this saves me a lot of back pain!

I've also noticed that there's way more native diversity in the sunny areas, and not so much in the shady areas. So that's definitely something I should focus on.

If you can identify any of the plants in my photos, that would be great!

Paul Eusey wrote:
This invasion is not a “symptom” of soil condition issues.

What makes you think that? If it's not a symptom of problems with the soil, it's a symptom of predator deficiency. If not an herbivore, than a bug or disease. If it puts off almost anything that tries to eat it, it's probably a pioneer, facilitating good soil conditions for the ecosystem to get to the next stage, in spite of even roaming goats. Very few plants can stand up to goats. Everything has a purpose.

The yellow-flowered bush looks like scotch broom, and the purple-flowered vine looks like vetch. These are both nitrogen fixers. This supports the hypothesis that pampas grass is facilitating succession towards a forest. This could also guide your seed choice: what native nitrogen fixers do you know of?