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The Deep Middle


Gardening & writing in the prairie echo

On Weeding -- When, How, Why Not To, and Patience

8/24/2023

 
When you disturb a site -- plant a new garden -- you WILL have weeds. These weeds are usually annuals, but they can get pretty thick in certain circumstances (especially in seeding projects where it takes longer for plants to mature, and where germination isn't always guaranteed if dependent on timely rains).

It's important to rethink weed management in gardens the first 1-2 years. For example, hand pulling every last intruder is both impractical and problematic; for the latter this means every time you pull a weed you create more soil disturbance, bring up more weeds seeds to germinate, and potentially exacerbate the issue.

In a sown meadow space, some folks recommend keeping the area mowed at about 6-12 inches the first year to reduce weed seed germination. I've worked on projects where this was helpful AND detrimental. Why detrimental? The space was sowed at such a high rate (over 200 seeds per foot) and using a healthy dose of biennials and annuals, that letting those early-succession species take off provided superior weed control -- even though we still had plenty of weeds. Luckily, it's harder for most to tell what is a weed and what isn't when there are so many flowers in bloom early on.

When there are more manicured / intentionally planted beds using potted material, there are some traditional strategies to reduce weed competition in years 1-2, such as a thin mulch layer (we recommend just 1-2 inches so there are / will soon be more soil gaps to allow desirable plants to self sow and fill in, thus creating a living green mulch sooner while fighting weeds sooner). Some pros try a pre-emergent, granular herbicide, especially for spring plantings. But the best strategy you can take is plant density -- planting at 12 inches apart or less -- and deadheading problematic weeds. The goal is always to cover the site ASAP and not allow invasive weeds -- like musk thistle -- to get a foothold, and that's where deadheading really helps.

If you're planting into a known weedy site -- especially one with aggressive species like creeping charlie -- it might be a good idea to prep the area for an entire growing season before planting. If you solarize, this means a 4 weeks on / 2 weeks off with the plastic (kill plants, let new weeds germinate, kill, repeat), or similar treatment with glyphosate (let weeds grow to 4-6" then kill a few times -- each time it will be less and less). Using cardboard may not be always be practical if you have large areas or are seeding.

It has been one heckuva year for weeds in 2023. A super dry winter and spring AND early summer, followed by much rain in July. This produced a bumper crop of weeds and later in the season. Luckily -- and as is most typical -- the weed pressure has been mostly from annuals such as crabgrass and foxtail, both of which are almost always out competed by desired plants within 1-2 years as those annual seeds need light to germinate (and often won't get it if shaded by warm season bunchgrasses and forbs if planted densely in layers).


Unfortunately, we never know what's in the weed seed bank when we prep a site by killing lawn -- and spray-killing lawn is preferred vs. sod cutting or tilling, because more site disturbance = more weeds by the truckload. Each space is unique, with unique hydrology and weather and even microclimates. It's been a very surprising year with plenty of hiccups in our landscapes, but patience and staying the course is critical. When we are ready to give up that's usually just about the point when the corner is being turned.

Remember, a weed is an undesirable plant in a place we don't want it. And weeds thrive where there's an opportunity -- open gaps with little competition. Nature abhors a vaccuum. In a new garden -- whether planted or sown -- desirable and necessary plant competition may be 1-3 years away. Patience is critical as the ecosystem rebalances and heals itself from a long history of colonization.


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James McGee
8/31/2023 12:40:28 pm

I cut weeds at ground level, cut weeds under the crown, or if necessary remove weeds by the roots in establishing native plant gardens. Here are my experiences with my local park district spraying herbicide to control weeds in a garden I had been maintaining.

https://stewardshipchronicles.blog/2023/05/06/death-to-a-native-plant-garden-5-6-2023/

https://stewardshipchronicles.blog/2023/07/14/death-to-a-native-plant-garden-7-13-2023/

James McGee
8/31/2023 10:50:50 pm

It is really frusterating reading anti-weed removal arguements. Yes, when a weed is removed roots and all more weeds grow. Long-lived native plants grow slowly and take time to fill the space. What people fail to mention about removing weeds is there are weeds that are space filler and there are weeds that will dominate the whole garden. If you remove garden dominating weeds and they are temporarily replaced by space filler weeds this is helpful. Long-lived native species overtake space filler weeds and the garden will move toward a lower maintenance “old-growth” state.

People take the ‘don’t disturb the soil because it causes weeds’ rhetoric as an arguement to spray herbicide. Spraying herbicide causes a much greater disturbance to the plant community than physically removing weeds. People fail to realize herbicides also disturb soil. Over the long-term, people conducting ecological restoration have found a higher-diversity is achieved if sod is only burned before seed is sown rather than first spraying herbicide before burning and sowing. In a suburban setting, scalping the lawn should provide a similar effect.

Bluegrass and ryegrass both tend to be overtaken by native plants. In contrast, fescue lawn persists and can dominate requiring control. Spraying blue grass/ryegrass lawn before planting native species will make your garden dominating weed problem worse. However, I am sure people will keep spraying before planting a native garden. Eliminating all competing vegetation to grow desired plants is what people do.

Jake Rayson
9/2/2023 04:34:42 am

Thanks for a really useful round-up of approaches. For intentionally planted beds, I've found an annual, temporary green mulch sown on top can work really well. In the UK have used White Mustard (Sinapis alba), which rarely reseeds.

> Nature abhors a vaccuum

I saw a quote by an ecologist a while back which was “Nature abhors a garden”!

Robert Lesko
9/2/2023 06:43:58 am

I've been inspired and informed by Ben's writing for years. His wealth of knowledge and experience is vast, But I can't quite bring myself to use herbicides to create a base for planting a new garden, though it might seem expedient. James Magee's comments above seem more sensible to me. I have used glyphosate foam to target the leaves of poison ivy and the roots of bittersweet in the garden, but can't bring myself to use more broadly. I will opt for my old Weed Dragon to scorch the lawn, weather permitting.

James McGee
9/2/2023 09:34:17 am

I use glyphosate foam to control invasive species in remnant prairie. I have done trials to determine the minimum concentration and amount that will work to kill a given invasive species. Using shoulder length chemical resistant gloves, with a second pair of disposible gloves underneath, I squirt the foam into a bundle of stems held in my hand. I repeatedly squeeze, and squirt more herbicide if necessary, while moving my hand up the stem until the plant is fully covered. With this careful method of only applying the minimum necessary amount of herbicide to the target plant, I can get selective control. Non-target plants are impacted but recover the next year. The non-target plants often grow better the following year without competition from invasive species.

The qualifier being the location formerly occupied by an invasive species may not quickly revegetate if the invasive plants were dense. At the levels of herbicide necessary to kill a densly infested area of invasive plants there may be persistence issues. These persistence issues can impact plant growth and prevent seedlings from establishing for a few years. This is a tradeoff that is worthwhile to get rid of the invasive plants so the ecosystem is not competely lost to the invasion.

Applying foaming glyphosate by hand is slower than damaging spraying but faster than trying to remove invasive plants by the root. Many invasive plants are so large that it would be unreasonable to remove them by the roots (large purple loosestrife, large reed canary grass clumps, woody species). In other cases, invasive plants spread in clones (flowering spurge, crown vetch) throughout the high-quality native plants. Applying glyphosate foam in the manner described is the only way I’ve found to eliminate these invasive plants without destroying the native plant community. I think of herbicide being applyed this way as medicine to rid a disease.

The one caution about applying herbicide this way is your face will necessarily be close to the application site. To avoid breathing herbicide vapors, I apply when there is some wind and hold my breath while doing the application. When I am done I stand up, take a few breaths, then apply herbicide to another plant, and repeat.

James McGee
9/2/2023 12:32:14 pm

Knowledgeable people will notice a mistake in my above post. When I wrote the common name of the native, flowering spurge, I meant the invasive, leafy spurge.

James McGee
9/2/2023 12:42:29 pm

Also, I wrote, “… while moving my hand up the stem until the plant is fully covered.” I actually don’t fully cover the plants but rather apply the herbicide up a minimum length of stem and leaves (from the base) to get the desired level of control depending on species and time of year of application. In fall, less herbicide is needed for some species than in spring.

Ingrid
9/2/2023 06:19:53 pm

It sounds like it works, but I hope your are also wearing a professional grade mask; you mentioned the gloves but not the mask.

James McGee
9/2/2023 08:30:28 pm

I wear an organic chemical rated respirator. They are about 40 dollars. However, I have found it is not enough. If there is not enough wind, I will get a head ache after applying glyphosate foam even when I wear a respirator. Although, the head ache does not last as long as before I began wearing a respirator. Even when wearing a respirator, I still make my best effort not to breath in the fumes. When I hold my breath during the application of glyphosate foam (until I can standup) I do not get a headache afterward. Not breathing in the fumes in the first place is better than wearing a respirator.

I should mention wearing a respirator is not required personal protection equipment per the label. This is something beyond what is required that I have found to be necessary for my purposes.

Alba v Tirado
9/7/2023 07:39:40 pm

Would using a torch also kill the roots or just the above ground leaves & stems?

Benjamin
9/7/2023 08:08:24 pm

Just the leaves.

James McGee
9/7/2023 11:50:34 pm

It depends on intensity. Benjamin Vogt is correct that burning the leaves off lawn grass will not kill the roots. If done repeatedly, it does cause the grass to grow thinner allowing other things, like prairie seed, to establish. The fire adapted prairie species then mostly out compete bluegrass and ryegrass. There will always be some bluegrass, but it is sparse when competing with prairie species.

In contrast, extremely intense fire, as can occur in western forests, can sterilize the soil to the point nothing grows but what is able to recolonize from other areas.

Fire, either from burning thatch or from a torch, can kill small woody species. I observed a two year old common buckthorn was killed by burning my sedge meadow. Frequent burning has kept common buckthorn and Asian bush honeysuckles from getting established in prairies where they have been eliminated by control efforts. As fire intensity increases, even larger trees not adapted to fire, can be killed.

Karen
9/2/2023 08:39:05 am

Monarch Gardena LLC encourages the use of herbicides? This does not seem right to me. I think I shall unsubscribe.

James McGee
9/2/2023 10:06:06 am

Benjamin is just doing what is the industry standard. Please give him time to consider that killing bluegrass/ryegrass before planting native species may not be necessary or even helpful. I expect he will try both ways and see if it works for himself. Still, since he wants the work he will have no choice but to spray to kill bluegrass/ryegrass lawn before planting for some customers. People tend to think eliminating all unwanted vegetation before planting is the only way to garden. As agriculturalist, we humans have had a long history of managing land in this way.

Besides, if you unsubscribe you will miss seeing all the beautiful pictures.

Robert Lesko
9/2/2023 12:22:02 pm

Ben has been very upfront about his reluctant use of glyphosate in the circumstances he describes.It's a complex problem that does not lend itself to easy solutions and pros and cons have to be weighed in the interest of developing practical protocols that lead to a healthier environment. I guess as individuals we have decide what are acceptable trade-offs.

Ingrid
9/2/2023 06:09:48 pm

I have read his book ‘Prairie Up’ and Ben does not advocate for herbicides. That would be killing the pollinators that come to his gardens and one of the main reasons he does this work. I would encourage you to read his book before unsubscribing. Ben will not eliminate a ONE TIME or TWO-TIME use of chemicals as an efficient and cost-effective way of establishing a project if the site warrants that approach. People fail to see a difference between establishment and continual use of pesticides, nor do they understand the power of perennial noxious weeds officially listed on provincial and state weed lists. Each site must be evaluated on its own merits. All tools in the took kit need to be considered: grazing, mowing, biological control, burning, tilling, timing, financial resources, volunteer labour, pulling/cutting, smothering and possibly chemical control etc. There is no “one size fits all”. In the book he outlines the problems with solarization and the current science on soil health. If you still don’t agree with him on that subject, he still has much wisdom to offer on all things prairie. Yes, by all means advocate for less chemical use, but remain in the conversation.

Paige link
9/3/2023 01:16:46 pm

As always, I appreciate the wealth of practical info you offer. I'm curious about crabgrass: when is it too late to mow to control...ie, when are the seeds mature? I haven't been able to find this information anywhere. Maybe my assumption that mowing...even when the seed heads are forming...is a way to stop its cycle. But maybe even immature seedheads wilil ripen after being cut? I have a large area that I'm observing...and only mowing a couple of times...to see what's there and what I will be dealing with. There is A LOT of crab grass... Pulling it isn't really an option. Thanks!

Benjamin
9/3/2023 01:21:55 pm

I'm experimenting now on a couple different sites. This I do know -- if there is good density and layers for desirable plant, they can win out. We have far more issues in seeding projects because we're not using wood mulch; in mulch beds it's less crabgrass and also easier to see where to pull / treat. Even after you mow, crabgrass just keeps putting out seed heads. As an early succession annual that's taking advantage of an open niche and that theoretically helps heal a site, I'm letting it ride on some landscapes. I would NOT do this if you are in an anal retentive neighborhood and / or it's a designed border -- just talking seeding projects here on larger landscapes (10,000' and above).

Paige
9/5/2023 01:39:57 pm

Thank you! It is not a designed bed...and the site is out of view of offended neighbors...so I will continue to observe until I decide how I want to approach the space.

Benjamin
9/3/2023 01:24:38 pm

For those upset about a one-time use of glyphosate, I've written about it extensively in my book and on this blog, while speaking about it in countless lectures. This is NOT a black and white issue, and restorationists would be up a creek without this tool (and they are using it as a tool, smartly, unlike too many homeowners who don't read label directions or don't consider other methods as suited to site -- esp in the case of after-install management). https://www.monarchgard.com/thedeepmiddle/to-spray-or-not-to-spray-garden-site-prep-and-reviving-biodiversity

James McGee
9/3/2023 03:26:03 pm

The problem that can arise from using glyphosate to prepare a site is it can actually favor certain resistant weeds, like bindweed and field thistle. (See links in my previous comment) There are also observations that it prevents the establishment of some prairie species. The link below has Rich Henderson’s experimental results from years of conducting ecological restoration.

https://www.youtube.com/watch?v=hvMy--MMM2c

James McGee
9/5/2023 03:51:37 pm

Unfortunately, not all restoration practioners are using herbicides smartly. There is a lot of “spot” spraying weeds (and sometimes even shrubs and entire trees), which also kills any good native species adjacent to the location. Spraying herbicide is even being done in the best quality natural areas in the state (Illinois). I have seen spraying killing quality native species within the spray zone while not killing the targeted invasive species. The result being progressively less native species coverage and more invasive species coverage. There are a lot of people out there causing a lot of harm and some are getting paid to do it. However, the companies that do this are less expensive and continue to get business. Sometimes the problem is the state itself that dictates how management has to be performed. Other times, it is a lack of knowledge. I am trying to follow some of the projects occurring in the area where I live and document the results of work on the folowing blog.

https://stewardshipchronicles.blog/

John
10/20/2023 09:25:03 am

I've not been here long and I know practices can and should vary by region, but it seems like you tend to lean away from the use of wood chips beyond a thin layer like you mention in the above post.

Why is that?

Disclaimer is that I'm not a habitat restoration person or anything, just a homeowner with a small lot and an environmental-ish background. I'm one if those people who loves to flag down the various arborists in/near my neighborhood and have them drop off fresh wood chips which I then spread over areas of lawn and/or areas that I want to garden in that used to be covered in river rock and landscape fabric, courtesy of the previous owners. Usually I spread it 4 inches thick or more. My reasoning is to deprive the existing weed seeds and/or grass of light to such an extent that they won't recolonize or at least will be much more manageable.

I also don't really see a downside to adding this hefty amount of organic matter due to the relative lack of an O horizon in most typical neighborhood lawn situations. Additionally, I'm trying to lean on the general correlation of susceptible habitats to invasion being ones that are also highly disturbed. Highly disturbed soils have a high amount of free nitrogen in the soil. Early successional environments, by and large, are "hot", they have an ample amount of nitrogen that fuels the growth of those crazy weedy species. I had a botanist tell me once that you could think of early successional species as disturb-o-philes or nitrophiles and it seems pretty accurate every time I try to look at the landscape that way. We see this in our yards when we plant native plants that *should* only get 3-ish feet tall and they end up pushing 5 or 6 feet tall and flopping all over the place.

My point is that I try to balance out this excess or abundance of nitrogen with a relatively large infusion of carbon to kind of fast forward through that chaotic, early stage of disturbance that comes with any garden installation. Fwiw, I've planted plugs and bulbs of natives directly into 1-2 week old layers of wood chips and they've established just fine. I prefer to spread the chips in fall/winter to let them settle a bit but life isn't always convenient like that.

Would love to hear any thoughts on this. I'm kind of assuming it's more of a practicality thing with the physical labor involved with acquiring, hauling, and spreading several yards of wood chips which is understandable but I wanted to see if there were other reasons along the lines of succession and stuff like that.

Benjamin
10/20/2023 10:21:45 am

If you read Prairie Up you'll get all the answers! ;) The reasons your plants flop is because they did not evolve to have so little competition from other plants. Mulch also keeps these plants in a perpetual state of establishment. Using so little mulch JUST at install means we reduce annual weed pressure the first year until the planted, desired species can begin to fill in and self sow -- which is EXACTLY what we want. More plants = fewer weeds and and a more sustainable landscape provides all sorts of site stabilization benefits. Mulch is something we've been tricked into. We don't see wildlife mulching, and we don't see mulch in woodlands or meadows -- we DO see plants, lots of layers, lots of density. Wood mulch really only started to be pushed in about the 1970s and 1980s as pulp mills had extra product they didn't know what $ to do with.

John
10/23/2023 12:34:22 pm

I'll be reading it soon-ish once the other 11 people who have it on hold through Libby get out of the way haha.

Before I address the flopping thing I want to be clear that I do agree with dense planting for various reasons, aesthetics and faster establishment being some key ones, but the flopping reason isn't really one of them. I do see what you're saying and I agree that in most historical (pre-colonization in this case) situations, plants grew more densely than you find in your traditional urban or suburban garden. The, "1 plant every 2 feet in a sea of dyed mulch," look is... just, yuck. But I think it's worth pointing out that there is a genuine structural weakness that plants grown in high Nitrogen environments, particularly ones high in urea and ammonium, experience. Their internodal length is much larger compared to plants grown in lower nitrogen environments and that does promote this inherent structural weakness that makes them prone to flopping. Densely planting them can reduce this tendency, but in my opinion, it's likely due more to naturally reducing the amount of N any one plant has access to and takes up, both through competition and cooperation among those plants. I'm sure the tendency to flop is also reduced when there are other plants to nearby, both to lean on and to create a more populated and stable soil structure but I also think there's more to it.

On the mulch thing I am curious what you mean by, "keeps these plants in a perpetual state of establishment." Do you mean their growth is stunted and they fail at establishing in a way that requires additional plantings or seedings?

I also think some context should be added to the mulch convo. Sure, we don't see wildlife mulching in the way we're discussing, nor do we see mulch in woodlands or meadows. But what we do see in remnant prairies and old-growth forests is a layer of decomposed organic matter that is at least a foot (frequently many feet) deep. That is what I'm trying to achieve. This organic layer that has been scraped clear and eroded away into our waterways for 200+ years. One of my goals with spreading wood chips, not dyed mulch to be clear, is to offer a foundation for that organic layer to form and jump start it. Wood chips just happen to be easy to get for me relatively abundant for no cost. I would happily use another source of high-carbon organic material if I no longer had access to any wood-chips. Point being, the carbon rich organic material is what I'm after and that same thing *would* form over time with the death and decomposition of plant roots, of tree leaves, of branches, of whole trees, of scat, of entire animals, of prairie grasses and forbs, and so on. By doing it your way and using a thin layer of wood chips at install, this O horizon formation still occurs, not arguing that at all. But that process takes much longer than the afternoon or weekend I'd spend spreading wood chips somewhere. I'm really not trying to shill for the wood pulp industry or encourage people to buy 2 cu. ft. bags of mulch to cover their property in. But I do think that wood chips, or even well-finished compost for example, are tools that have more uses than frequently given credit for, especially when laid on thick. One of the most exciting things to me is the effect that a C:N ratio more tilted to carbon seems to have on plant communities and plant growth overall.

Late successional communities are ones that are frequently carbon rich and nitrogen poor while early successional communities are the opposite. Stable, late-successional communities are much less susceptible to invasion than chaotic, early-successional communties. Late successional environments see very steady, rather slow growth year over year, whereas early successional communities usually resemble something between an Impressionistic rendering of a green haze and the inside of your toilet bowl after sampling the efforts of your buddy's microgreens grow op in his basement. Just swirls of green and everything falling all over the place. Invasive grasses, thistles, native brambles of all sorts, just an explosive mess of growth for a few years until the system starts to stabilize and that abundance of nitrogen has been utilized to the point that the longer-lived species start to show up and a recognizable community matrix starts to emerge. You talk occasionally about crabgrass and other common weeds and how they tend to fall off after a couple years. I'm talking about the same phenomenon, just through an additional lens of nitrogen management.

Anecdotally, gardens I've put in where I've only put in a thin layer of wood chips have had more issues with weeds and super-charged growth on natives compared to gardens I've put in where I've put 4"-ish of wood chips, even when plugs are planted on the same spacing. I usually go 12" or less if I want a nice tight clump of something.

Anyway, sorry for the lengthy post. I just think it's neat and usually end up going on and on

John
10/23/2023 12:47:54 pm

Nothing really says, "man, just shut up already," like exceeding the character limit. Finished response below.

"...about it. Looking forward to reading the book when I finally get it."


Comments are closed.

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    Benjamin Vogt's thoughts on prairie gardening in Nebraska. With a healthy dose of landscape ethics, ecophilosophy, climate change,  and social justice.

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