Killing + replacing a large patch of weeds w/out toxins?

September 1, 2022 11:23 AM

I am trying to improve a yard that has been neglected for decades, and is full of invasive plants. I have some questions for anyone who has successfully tackled a project like this.

I'm basically looking at ~2500 sq. ft. of weeds (Japanese honeysuckle, porcelain berry, tearthumb, English ivy) and rubble, as well as some natives that are either undesirable (poison ivy) or are growing in such profusion that they need to be curtailed a little to make the yard usable (pokeweed, Virginia creeper). I want to do the following:

1. Gradually kill off the weeds w/out Roundup or other toxins. I am handpulling, but am doing this mostly solo, so looking for suggestions to speed things up that have worked for you (e.g. smothering with cardboard sheeting).

2. Begin replacing the weeds at scale w/native or near-native plants that will provide food for birds and pollinators. I am going to buy individual plants, but am looking for successful experiences with broadcast seed of either wildflowers or groundcover. It seems like, to get ahead of this, I need to begin shading out and providing a lot of competition for the weeds, in addition to pulling them.

Looking for advice from MeFites with practical and successful experience in similar projects.

posted by ryanshepard to Home & Garden (24 answers total)

Use hack and squirt application of herbicide on the honeysuckle. This is incredibly safe and effective, it exactly what scientists recommend and restoration experts promote. There is literally nothing to gain by not using a small amount of eg Roundup on this scale. There is zero by-kill and zero runoff if you follow the directions. Now is actually one of the best times of year to do this.

If you you really enjoy fighting them with your bare hands go right ahead, but all of your efforts will be for nought until you completely eliminate it from the area.

I am a plant ecologist with some experience in converting yards to native plantings. I am also a bit of a crunchy hippy and advocate herbicides only in very few situations, but I implore you to do so here, so that you can reap the benefits of restored land much faster and cheaper. Seed is only effective if you have done 100% of preparation perfectly, and if you won't use herbicide on the invasive species, then my advice is to go slower and only buy plugs.
posted by SaltySalticid at 11:35 AM on September 1, 2022 [12 favorites]

I have successfully used one layer of cardboard (shingled so there are no gaps) covered up with a thin layer of mulch. Bonus to this technique is that the cardboard breaks down eventually. To plant, cut holes in the cardboard and closely fit around the plant stalk.

You'll be continually faced with opportunistic seedlings sprouting every year as they blown or dropped in, but it will be far fewer than hand pulling all.

At approximately every three years or so, in areas showing excessive invasive seedlings, I pull the remaining mulch aside and reapply cardboard as needed...no need to remove existing....
posted by mightshould at 11:40 AM on September 1, 2022 [3 favorites]

Best answer: From my experience: some weeds get worse with handpulling. Little broken bits of root can yield more plants than you started with; repeated over many sessions you can inadvertently make a thick carpet of weeds. I made my own yard worse by this method for a long time, until finally I gave in and used Roundup applied over several weeks to kill it down to the roots and then followed by handpulling and covering the ground with landscape fabric (cardboard would also be good).
posted by LobsterMitten at 11:53 AM on September 1, 2022 [4 favorites]

I'm with SaltySalticid, use an herbicide to get ahead of the invasive plant problem and then all the good soil-building and native plant work can pay off. Completely read the label of whatever product you use. I am also an ecologist and have applied herbicide and handpulled on restoration projects, they don't compare. You can't plant seeds into ground with established invasive plants and expect them to compete.

When you say handpulling, are you digging out the roots? Just ripping off the aboveground parts isn't going to work. If it's just you, you may want to focus on doing one area at a time, that's a lot of ground to handle.
posted by momus_window at 11:56 AM on September 1, 2022 [1 favorite]

(It's possible that boiling water or fire could be used to kill the weeds in the first step? They have those flamethrowers that are for weeds. I didn't try either of these methods.)
posted by LobsterMitten at 11:56 AM on September 1, 2022

For context, my backyard was overrun with Himalayan blackberry. I spent hours digging out what I could, then sheet-mulched with cardboard and several inches of wood chips, then applied a triclopyr product in the fall on the shoots that came back. I did a little more digging the next year, applied triclopyr again in the fall to the remaining shoots, and I still have a couple bits to spray this year.

Don't set this on fire without someone with training in restoration fire running the operation, this is a sizeable area and careful timing of the fire is important / it may be inappropriate for your site. Boiling water over a large area will also destroy your friendly local soil microbes and invertebrates that you want to support your native plants / soil texture.
posted by momus_window at 12:03 PM on September 1, 2022 [1 favorite]

(It's possible that boiling water or fire could be used to kill the weeds in the first step? They have those flamethrowers that are for weeds. I didn't try either of these methods.)

Boiling water can work on annual weeds, but perennial weeds with a long established rootstock will not be fazed when their tops die back. And though I am absolutely not an advocate of RoundUp or indiscriminate use of herbicides, this is the exact application it is made for. RoundUp/glyphosphates' effect on soil biota are negligible, and if used with all precautions is probably safer for an individual than repeatedly carrying boiling pots of water out to the yard.

Those flamethrowers for weeds are also not designed for a yard full of undesirable plants. You'd effectively be setting a garden on fire in a long, slow tedious process. Those torches are designed for occasional weeds in gravel pathways or sidewalk cracks.
posted by oneirodynia at 12:16 PM on September 1, 2022 [1 favorite]

Can you all speak on the effects of Roundup on vertebrates?

I am interested in this thread since I also have serious invasives and have been avoiding using herbicides because I have so many delightful amphibians in the yard. Right now I could walk out my back door and pick up a toad, and with a little more effort find some salamanders.
posted by Lawn Beaver at 12:30 PM on September 1, 2022

Best answer: My back yard has a lot of invasives (looking at you, creeping buttercup), but I am in process of mostly having tackled a huge patch of blackberry. A few years ago, I hired a friend who HATES invasives to pull out the blackberry, which also involves getting as much of the root as possible. She piled on heavy clothes and gloves and went at it. Now, I hand pull things a few times a year as they come up, but the huge effort and amount of work she was able to get done during a few focused hours was extraordinary. Worth every penny.

I also love the idea of broadcast seed, but I did a consultation with the local backyard bird/native plant folks, and they advised against it. They recommended sheet mulching large swaths and then using plugs. If you broadcast seed on healthy soil, you're also going to attract a lot of new weeds, and, when things grow, you won't know which are weeds and which are the flowers and plants you want. If you sheet mulch and have healthy soil and then use plugs, you can mulch heavily and hand weed around it all as little things pop up.

So that's my plan. The creeping buttercup is an area I was considering leaving as grass, but I might go ahead and lay down some cardboard and mulch to kill it all off before it takes over everything.
posted by bluedaisy at 12:39 PM on September 1, 2022 [2 favorites]

Some formulations of glyphosate (the active ingredient in what most people call Roundup) are labeled safe for aquatic use. It's very useful for killing invasive brush on eroded banks near streams. The label information for the particular product you find will tell you how to apply it safely around wildlife. Glyphosate gets overused (IMO) because it is so safe for things that aren't plants and so effective as an herbicide and that's why it winds up as a target (also Monsanto is evil - you can get glyphosate from companies that aren't Monsanto).

I use PICOL to search for pesticides for various uses, you might want to consult your ag extension / master gardeners / land steward program/
posted by momus_window at 1:02 PM on September 1, 2022 [1 favorite]

Can you all speak on the effects of Roundup on vertebrates?

Glyphosate (Roundup) is incredibly harmful to amphibians if it gets in waterways. There have been claims that glyphosate carcinogenic with chronic exposure, but many studies have failed to show any clear link (keep in mind the brown crust of bread is mildly carcinogenic too.) Glyphosate breaks down quickly after use, and even very concerned review articles note that " acute toxic effects of glyphosate on fish and mammals are low".

Glyphosate is killing our planet, make no mistake. It's insanely massive scale of usage is behind our tragic global decline of insects and birds. The problem is not carefully squirting a few droplets into tough woody invasives. The problem is dousing literally hundreds of millions of acres with it, across the country, several times per year, to grow GMO products (primarily corn and soy, the vast majority of which is used for animal feed for animals raised for human consumption).

Talk to your local extension office for more specific guidance, but suffice it to say that there are many reasons why professional scientists, educators and NGOs involved with conservation and restoration advocate for its careful use.

It's the dose that makes the poison. If you are concerned about Roundup as used rampantly and freely in industrial agriculture (and you should be), you are going to be far more effective by reading the science and writing your congresspersons than you can be by abstaining from using it with proper care and education on your property.
posted by SaltySalticid at 1:10 PM on September 1, 2022 [12 favorites]

Best answer: I got cardboard from various neighborhoods on trash/recycling night, and we're coming up on leaves in big compostable paper bags time. At one point I scored some used chipboard and killed a big area of knotweed; the chipboard composted nicely. For my garden, I was able to get quite a lot of free newspapers from an agency that publishes them. 6 -9" of cardboard & newspaper topped with paper bags of leaves composted over a winter, turned in the spring and had fluffy leaf mold to which I added soil.

SaltySalticid, I know someone who used that method on knotweed and thanks for the encouragement. I nearly got rid of it, but the power company cut down trees, allowing sunshine in an area that had been shaded, and the town re-dug the ditch (unnecessarily) , removing the existing plants, and knotweed is incredibly opportunistic. sigh. It takes so much effort to battle invasives.
posted by theora55 at 2:43 PM on September 1, 2022 [1 favorite]

Best answer: I should add that my encouragement for roundup was really restricted to the honeysuckle because it is in a separate category of harm and resistance to mechanical removal or smothering.

Smothering with cardboard and lots of mulch is a great and effective way to deal with even some petty bad herbaceous invasive species and other problematic weeds. In some applications, solarization is another good option. Using those and some other things mentioned above (fire, boiling water, can help eliminate most household uses for herbicides.
posted by SaltySalticid at 4:09 PM on September 1, 2022 [3 favorites]

Have you considered renting a herd of goats to clear the brambles? Apparently they love to eat poison ivy and blackberry canes and other brambles and underbrush-y sort of stuff, plus they are very very environmentally friendly. I was surprised to see there were several places that hire out goats within an hour’s drive of me. I can’t speak to your situation, but it might appeal to you?
posted by fancyoats at 5:29 PM on September 1, 2022 [1 favorite]

Instead of cardboard, if you can contact local demolition or carpeting places, you may be able to pick up houselots of old carpet, which makes an excellent weed suppressor. You will have to dispose of the remains of the carpet afterwards though.

Regarding goats - only consider this if you have REALLY good fencing.
posted by HiroProtagonist at 6:06 PM on September 1, 2022

(Most places that hire out goats will bring their own portable electric fencing.)
posted by fancyoats at 7:01 PM on September 1, 2022

Don't ever burn poison ivy, the smoke is toxic and will fuck up your lungs.
posted by emjaybee at 7:10 PM on September 1, 2022 [1 favorite]

We got a ChipDrop and have smothered the area with arborist wood chips to kill or at least prevent spread of mallow, bindweed, and other random weeds. (I still pull some by hand.) Working decently (after a failed single round of Roundup & reseeding with native drought friendly grass failed).
posted by deludingmyself at 8:35 PM on September 1, 2022

Sheet mulching or goats. (I’ve done the former, not the latter.)
posted by matildaben at 11:45 PM on September 1, 2022

Another option that may be on the acceptable side of herbicides: agricultural grade vinegar (30% vs the usual ~6% kitchen-grade). Smells like you're making a big salad!
posted by thandal at 8:31 AM on September 2, 2022

If no goats then sheet mulch.

Sheet mulching with cardboard, wood chips and effectively start a lasagne bed with desired species on top.

Black sheet plastic can also be used in high summer to solarise and effectively cook the top layer of plants and soil.

Weeds will grow because soil is out of whack in some way so getting a thorough soil test made for nutrient levels and potential toxins would give you guidance abou how best to amend the soil so that it is less favourable to the unwanted species.
posted by pipstar at 9:12 AM on September 2, 2022

Howdy neighbor, thank you for making the DMV a better place for wildlife! (Hopefully you are indeed asking about a yard in the DC area as listed your profile because some of the below is location specific.)

I'll start by echoing the many voices above saying that herbicides are indeed often the best tool for the job and one should not rule out their use prematurely. I especially want to second SaltySalticid's observation that glyphosate can simultaneously be both an absolutely terrible thing for the planet overall and still be the right tool for people doing righteous work.

That said, I do not think herbicides are necessary for the project you describe. At the scale you are working, the aforementioned "hack and squirt" is really the only applicable chemical technique I am familiar with. (I consider "cut and paint" a better descriptor for my preferred variation on the idea.) That technique implies a woody plant, however, and based on the common name you used as well as the other plants you mentioned in the cohort, I'm guessing the honeysuckle is a vine-y species rather than a bushy one and thus won't have a lot of stump to apply chemical on. Of the species you mention, only a mature porcelain berry vine would be a good candidate for hack and squirt (assuming not we're not talking bush honeysuckle).

The two most important tools you need at this stage, in my opinion, are a lawnmower and plan.

Now I'm as anti-lawn as the next D.Tallamy disciple, but I really think starting with a couple of mows will get things moving in the right direction. In particular, I've had really successful experiences mowing vine honeysuckle. I don't know why but it just does not seem to like being cut. I've even seen good results with a single pass followed by pulling any straggling vines still standing (albeit that was a case where desirable plant communities were already nearby). The porcelain berry and english ivy roots will not give AF about the cutting, but at least you'll make them waste some energy sprouting foliage anew. Neither will spread as a result. The mower will also put the tearthumb in its place quickly, though I do not know how the roots will react. Note that we are just on cusp of tearthumb fruiting season so if you see any of those bumpy blue fuckers you should collect and dispose of them first and foremost. (Disrupting reproduction should always be the primary strategy of any anti-invasive plant effort.)

So, yeah, mow the whole yard once with the blades on the highest setting, then get out your pencil and paper and make a plan. I just mean a quick sketch that indicates where the "use" areas will be vs the "wild" areas. As your use area, I'm picturing a semi-circular area near the house where you might put some chairs or a cornhole set or whatever and maybe some paths through the yard as well. Everything else is a wild area. Making this simple distinction now will be useful for mulching and planting decisions.

Ok now go back and mow again, this time at the lowest blade setting. Leave the trimmings in place and put away the mower. You are done with it for this season (or possibly forever if you borrowed it). Next mulch. Mulch is any organic matter that won't resprout (i.e. don't use the invasive vines you just pulled but their leaves have potential). It could be store bought bags or straw or a chip dump or, as others have mentioned, the bags of grass trimmings and leaves your neighbors are throwing away. If you use straw double the depth. (Please do not use landscape fabric or old carpet; this only creates additional problems.)

Sheet mulch your use areas: use brown cardboard with no tape on it, or thick layers of newspaper. Boxes with fancy color graphics will not break down as well. Top with 3 or 4 inches of mulch mulch. (When I replaced about 700 sq feet of front lawn a decade ago I used a very lightweight electric rototiller before sheet mulching. It worked well but I'm not sure it was necessary based on sheet mulching smaller areas in the time since, especially if there's no grass to kill.) (Also you may need to add some soil in the "rubble" spots?)

Don't bother sheet mulching your wild areas. Instead go deep with the organic matter, at least 9 inches. 12-15 is better. Go lighter near any pokeweed and virginia creeper you decided to mow around. (Both are awesome plants by the way but I get wanting to keep them under control.)

Then comes the fun part: plants. Grass/clover mixes are mostly ok for your use areas. Tallamy believes replacing just 50% of U.S. lawn area with natives will be spell success for Homegrown National Park. Ideally some violets (Viola sororia) will find their way into your grassy areas over time, as will some unobtrusive volunteers from your wild area plantings. Violets will be readily available at swaps if they don't come naturally.

The wild areas should be primarily natives, of course. If you are lazy like me, you'll want the aggressive ones which hold their own among the invasives (inevitably to come back to some extent) and which need basically no maintenance. I've had good luck in this regard with sea oats, Chasmanthium latifolium. Perhaps too good as it's the only native I've ever regretted planting for its aggressiveness. If your yard has sun to partial shade, they would be a great option for choking out the vines. (Though I'll note bindweed will not be choked by anything. Pray it does tag along in your mulch. Pull at first sight.) Memail if you want me to dig some sea oats for you. My wife will thank you!

Another planting I've personally had success with holding their own is a combination of blue mistflower (Conoclinium coelestinum) and spiderwort (Tradescantia virginian). The mistflower starts rising from the ground midsummer just as the early-waking spiderwort is dying back to nothing. Both are dominating plants in their season. Buying either of them commercially is not likely a pure native move, but I'm pretty meh on the importance of that personally in an urban/suburban garden. Finding some wild boneset that has gone to seed could substitute for the mistflower. They are blooming in white now.

Similar to collecting the boneset, you might notice goldenrods blooming soon in fields and roadsides around the area. Note where you might reach some without trespass and return in a week or two when the yellow flowers have turned to graywhite seeds. Collect your share by shaking the plants over an old sheet. Any sunny spots in your yard that are set well back from your use areas would be perfect to turn that sheet out and shake some seed.

A final plant idea that I've heard good things about beating invasives, but have not tried myself, is Packera aurea. There's a facebook group that I count among the greatest repositories of wit, kindness and knowledge in the whole history of internet discussion boards that informally calls itself the "Church of the Holy Packera". If you've already been zucked, I highly recommend making the best of it by joining. There's a plant swap in Takoma Park on Sept 17.

These aggressive plants will be your base which can then be filled in with the plants you love but maybe take more care to keep going. You may want to consider which pollinators and wildlife you hope to attract and research their specific hosts.

Thank you again for doing this work. So many thanks to all y'all doing it! The tasks can be overwhelming. Knowing I am part of this giant effort really helps keep me going. *insert Blues Brothers Mission from God gif*
posted by Press Butt.on to Check at 11:48 AM on September 2, 2022

Best answer: Reading back that sounds like an awful lot of work! I didn't really mean to try to do everything at once. Clear and defend space for natives. It may take years to do the whole yard but that's ok. Clear and defend.
posted by Press Butt.on to Check at 12:01 PM on September 2, 2022

The mulching bit will be the easiest part to contract out if you do decide to move as fast as possible, and the least fun to implement.
posted by Press Butt.on to Check at 12:03 PM on September 2, 2022