In the fall of 2019, I was tasked with taking a somewhat unsightly butterfly garden made up of native plants of the prairie and completely rethinking it. Like many smaller habitat landscapes, the garden was the victim of good intentions that failed to deliver in the looks department. Rather than looking the hoped-for (and promised by the nursery) wild and free, the space ended up looking weedy and unkempt. Penned in on two sides by a building wall and a fence, the landscape simply needed a discernible structure that the original packet of all-native plants of the prairie (planted in 2017) just couldn’t seem to deliver on its own.
The butterfly landscape before the rework, lacking a discernible structure and looking like a weed bed.
I will clarify here that while I readily use native plants in the landscapes I design and install, I have long been somewhat unnerved and troubled by some of the broad and sweeping claims that native-plant accolades and purists have made over the years about their beloved plant materials: that native plants are all low-maintenance and drought-tolerant; that wildlife such as bees only like native plants and that non-native plants are the equivalent of botanical junk food, and that native plants are always better than non-natives in any context and within any setting (see a recent opinion piece on the idea of native plants being the answer to the abject ugliness of LA in its lead-up to the Olympics).
But the claim that has sat the least well with me? That native plants need to be planted with each other and can’t be mixed in with nursery cultivars or plants from other parts of the country or world because those interlopers will take over and choke out the natives. Over the past 15 years of doing landscape design and installation, these claims simply haven’t squared with what I have literally observed on the ground and in the dirt.
From the get-go, I have mixed “native” and “non-native” plants, adhering not to an approach of cordoning plants off by geographic provenance but instead to the approach of simply grouping plants with like needs together. All gardens and human-designed landscapes are an idealized version of nature—including ones that are made up of all native plants. What I am trying to do is firmly acknowledge that reality but amp things up, creating a kind of hypernature that wouldn’t normally exist on its own and attempting to strike a balance between a looser wildness that brings in the wildlife and a structure that says to humans, “I’m an intentional space. Come in here and hang out a while. You’ll like it.” More often than not, the plants have seemed to proverbially get along, never creating some kind of feared spontaneous botanical combustion when non-native touches native.
The Frog Park Climatescape, designed and installed by the author, in Oakland, CA, an example of a thriving landscape that mixes native plants of California with plants from other mediterranean and arid climates of the world.
Still, it is one thing to observe and another thing to actually take a microscope to a space and study it long-term. Perhaps I was wrong. Perhaps over time, the composition of a landscape will change to the point where the nursery-grown cultivars will push out the natives. And this is what I set out to explore and learn after we had retooled the Minneapolis butterfly garden. To provide the space with some much-needed structure and discernible pattern and rhythm, we would plant a set of nursery-grown cultivars within the existing space of all native plants of the prairie. Then we would document how the species composition and number of plants within the overall space changed over time. In this way, I could get closer to knowing instead of simply observing what happens long-term within a space of “natives” and “non-natives” eking out an existence together.
On this level, the project had similarities to a project landscape writer and educator Noel Kingsbury had done called Competition Time, which looked at eight 5’ x 5’ plots of plants that also consisted of self-sowing plants and nursery cultivars and how the species composition of these plots evolved over time. While our space in question was a single one, much larger than 25 square feet (ours closer to 112’) , not perfectly square at all, and set within a climate radically different from the Competition Time plots (which were located in Hertfordshire in the UK), some of the plants we were planning on using were the same as those Kingsbury had used (Calamagrostis x acutiflora “Karl Foerster’ and Panicum virgatum, to name a couple). And the curiosity and some of the fundamental questions driving each project were the same: will one plant or set of plants ultimately reign supreme, or will a kind of equilibrium be reached?
Given these similarities, I reached out to Noel to see if he would be interested in having the Minneapolis butterfly garden rework be a kind of North American / Minnesota outpost for the Competition Time project, and he was on board. So for the next five years, I monitored the species composition of the Minnesota site and how it changed over time, laying a grid of 3’ x 3’ squares atop the site once per summer and documenting and counting what was growing within each. With COVID happening in the middle, we weren’t able to document the landscape in 2020, and then in 2022 our book, Dream Play Build, came out, and my partner James and I were just too busy traveling for the book. However, I was able to create sets of data for 2019, 2021, and 2023, ultimately painting one picture of what happens when nursery cultivars and native perennials and grasses are allowed to just proverbially do their thing together.
Laying out the initial grid and documenting the landscape
The project has ended up being a veritable journey of discovery, not necessarily confirming what I had suspected but painting a more complex and nuanced picture of what happens when you allow a kind of native/non-native ecology to take hold within a space and evolve as it will. While some of the discoveries and findings I made had to do with the initial questions at hand (i.e., would one or a set of species end up dominating the space?), others leaned more toward the aesthetics of the space, maintenance, and the challenges/opportunities of expanding this type of landscape creation out into a broader space and within a public setting where a crew, not myself, would be maintaining it.
Year 1: 2019 and what we started with
For the plant palette of the redesign, I selected seven cultivars to work into the existing space, providing the structure of the landscape, additional pollinator appeal, and serving as the “non- native” half of the experiment. Some of these were sterile cultivars, while others had the potential to self-sow. The selected plants included Calamagrostis x acutiflora ‘Karl Foerster’, Hosta ‘August Moon’, Hylotelephium spectabile ‘Autumn Fire’, Hylotelephium spectabile ‘Autumn Joy’, Nepeta racemosa ‘Blue Wonder’, Panicum virgatum ‘Heavy Metal’, and Sesleria autumnalis. These I arranged in more of an overtly structured way, with the Karl Foerster planted along a kind of grid toward the back and middle of the landscape and the others spaced at intervals or in clusters that would ideally tell the eye that they were planted there intentionally. Some of the existing native plants—especially those that naturally have more structure when not in bloom—I did move as well to also give the eye the sense that they had been intentionally planted there. These included the Liatris pychnostachya and the Monarda bradburiana.
The rest of the existing plants I left where we had planted them two years prior when we initially planted the garden, or where they had self-sown after the initial planting. There are too many to list here, but these existing plant species included all of those in the original nursery-curated butterfly kit, and some plants that pre-dated the butterfly garden itself but were not removed when we planted it in 2017. These pre-existing plants included a Betula populifolia ‘Whitespire’, Perovskia atriplicifolia, Liatris spicata ‘Kobold’, and Osmandrum cinnamomeum. Ultimately, the number of combined native/non-native species within the space totaled 28 (see chart for complete list).
List of plant species and quantities after the landscape rework and initial documenting in 2019
Once planted and mulch laid down, we laid a grid of 3’ x 3’ squares atop the landscape and within each square documented what was growing in terms of species and quantity. While the initial butterfly garden had been planted in 2017, already by 2019 there were certain plants that had found the site to be quite suitable for multiplying. These included (in descending order) Zizea aptera (counted 28), Agastache scrophularifolia (counted 26), Solidago juncea (counted 12), and Tridescantia ohioensis (counted 9). With the exception the ‘Karl Foerster’, of which we had planted 11, the quantities of the other plants remained at four or below. By the end of the first-year survey, we had counted 137 total plants in the landscape.
So the question now remained: Would some of these proverbial “winners” continue to dominate, or would some retreat into the background or disappear altogether? And would any of the cultivars start to self-sow within the site and compete for space with the other plants?
Year 3: 2021
COVID threw a wrench in our counts for 2020, so once we were vaccinated and able to travel again, I headed back to Minnesota in 2021 to use the same grid of 3’ x 3’ squares in the same locations to document how the landscape had changed. And indeed, certain plants had begun filling in the site with a kind of aplomb, namely the Zizea aptera, which had now totaled 57, a 203% increase from its previous 28. Others that had continued the march upward were the Solidago juncea (counted 27 / a 225% increase), Rudbeckia subtomentosa (counted 10 / a 250% increase), and the Perovskia atriplicifolia (counted 8 / a 226% increase). The Perovskia we had not planted but had existed on the periphery of the site at planting time in 2019. On the other hand, the Agastache scrophularifolia, which we had planted back in 2017 and had started to populate the site pretty extensively by 2019, had decreased in number from 26 to 13. And the Tridescantia ohioensis had gone from 9 to 4.
Photo of the landscape in late summer of 2021.
A few new arrivals had appeared as well. A Rudbeckia hirta, presumably from another landscape just 10 feet away, had self sown in the space, along with three Coreopsis palmata (also likely from the nearby landscape), and two Allium schoenoprasum, which had come from an existing clump just to the east of the landscape outside the study area.
As for the cultivars I had planted, they had come back from the long winter unscathed but had not self-sown at all. With sterile plants like the ‘Karl Foerster’, this obviously wasn’t surprising, but other cultivars such as the Nepeta racemosa ‘Blue Wonder’, which will self-sow under the right conditions, hadn’t planted themselves anywhere other than where I had planted the original three.
As for the total plant count within the space? We were at 192, a 140% increase over that of 2019.
List of plant species and quantities in 2021, including changes in quantities and species between 2019 and 2021.
Year 5: 2023
2022 was the year of extensive travel for our book, which had just come out and which made it difficult to block out time to travel back to Minnesota to do the counts that year. Fast forward to 2023, and I finally had a bit of downtime to do another round of counts.
By 2023, there were a total of 217 plants in the landscape, a 113% increase from 2021. Truth be told, by this point some of the 3’ x 3; squares within the grid were so densely packed with plants that to do the counts another year might have proven beyond human comprehension or capability— at least beyond mine. Either way, the number of plants reproducing within the space had slowed slightly compared to the time interval of 2021 to 2023 (140% down to 113%).
Photo of the landscape in the summer of 2023.
The plants that had previously dominated the space were still there, with the Solidago juncea showing the largest bump in numbers, going from 27 to 48, a 178% increase; whereas the Zizea aptera had increased in number but not in the way it had before, going from 57 to 62, just a 108.77% increase. Meanwhile, a new plant had started to emerge as one that was making its presence known, Asclepias syriaca, with 3 counted in 2019, 5 in 2021, and 9 in 2023. In fact, in my casual observation in 2024, the plant had appeared to have multiplied even more, numbering near 20, with one starting to grow within a clump of ‘Karl Foerster.’
Those plants that had gone from being more dominant in the garden to now declining included the Agastache scrophularifolia, going from 13 to 9, the Rudbeckia subtomentosa, going from 10 to 4, and the Asclepias incarnata, going from 3 to 1. All of the cultivars we had planted in 2019 had survived another winter except one of the ‘Karl Foerster’ specimens, going from 11 to 10.
As for the new arrivals in 2021, the Rudbeckia hirta had stayed at 1, the Coreopsis palmata had increased to 5, and the Allium schoenoprasum had increased from 2 to 3.
Learning from the results
What was clear from the numbers over the course of the five years of study was that the cultivars we had planted didn’t suddenly proliferate with aplomb and push out the native plants. In some ways, the opposite started happening: two of the most prolific plants—the Zizea aptera and the Solidago juncea—are plants native to the Minnesota prairie. And some of the native Asclepias syriaca ultimately started to grow within a clump of the non-native cultivar ‘Karl Foerster’ and not the other way around. Had we done the study for another five years, would this situation have changed? Would the dynamic have shifted to where the non-natives would choke out the natives? Although we can’t say with 100% certainty that this wouldn’t happen, given the lack of any kind of self-sowing on the part of the cultivars, and given that several are sterile, and then just the overall dynamic of the space’s ecology this far, it would seem very unlikely.
On a broader level, there was little indication that this mixing of “native” and “non-native” plants was a problem. We didn’t start to see large empty spaces around the cultivars where they were somehow preventing the native plants from growing. We didn’t see the nursery cultivars run amok or start “escaping” from the space and planting themselves elsewhere in nearby garden spaces. In fact, we in some ways observed the opposite – a Vernonia fasciculata suddenly appeared in the landscape in 2019 at the time of the rework, having self-sown presumably from a specimen in one of the adjacent garden spaces. And a Rudbeckia hirta and a thee Coreopsis palmata appeared in 2021. The closest we observed of one of the non-native plants moving into native territory was the Perovskia multiplying from 3 in 2019 to 11 in 2023. And yet in my experience with Perovskia, it does not seem to like growing within dense plantings but rather at edges or on its own. Within the Minneapolis butterfly garden, it is growing on the eastern edge of the landscape, where the original stand of Perovskia is and where there is full sun for much of the day and plenty of space between plants. In short, I’d be surprised if it made its way further west into the parts of the garden that are denser and that don’t get nearly amount of sun the eastern part of the space does.
Of course, one could argue that the cultivars, while they didn’t start actively crowding out the native plants, were, by their very existence, taking up space that could otherwise be devoted to just the native plants. This is indeed a line of reasoning of the strictest adherents to an all-native planting philosophy. However, this argument wrongly assumes all cultivars have zero ecological value, which is not true in the least. Have you seen a Hylotelephium ‘Autumn Joy’, a Perovskia atriplicifolia, or a Nepeta racemosa in bloom and the throngs of bees of all kinds that descend on them? Even the sterile Karl Foerster provides refuge and landing spots for dragonflies, damselflies, and butterflies, a phenomenon we have observed time and time again.
And yet on a much broader and deeper level, the argument that cultivars by their very existence crowd out natives misses the point of what this space and all human-created gardens and landscapes, save those created purely for ecological restoration, are: aesthetic spaces first and foremost. And indeed, the initial impetus for this project was to make the space work for both wildlife and human eyes and our psyches.
Photo of another landscape in Minneapolis designed and installed by the author. While a mix of native plants and cultivars, the distinct edges, paths, site lines, and repeated structural plantings tell the eye that the space is intentional.
If the overall objective is to invite people in to a landscape space and have that space resonate with them on a sensory and emotional level, we need to take people’s aesthetic reactions to landscape spaces seriously, as these reactions tend to be quite visceral and primal. We experience a garden first and foremost with our senses, and this is for a very simple reason: survival. Over time, we humans have evolved to try and make sense of natural environments quickly, to assess which ones might be threatening, and which ones might not. Sight lines, discernible patterns, and repetition can give us the calming sense that the space is both intentional and non-threatening. A lack of discernible order, thicket-like scrub, and an inability to see through the landscape can give us a sense that the space is forbidding and unsafe. Indeed, we can try and make more of an intellectual case that a space is beautiful because of its ecological value, but this approach will invariably have limited appeal, as it’s asking people to tamp down their primal responses to a space and replace them with intellectual and analytical ones.
And to do so risks shutting out folks who would otherwise be curious about the landscape. The reaction of “Wow, this is beautiful,” can be enough on its own, but it can also serve as a lead-in to learning more about the other layers that exist within the garden—that is, the ecological ones, the ones pertaining to pollinator appeal, the ones pertaining to water conservation, etc. In other words, the landscape’s beauty sparks a curiosity. On the other hand, the reaction of, “This looks like weeds,” is a curiosity-killer.
And so what about the plants that started to somewhat behave like weeds in the butterfly garden, or at least those that started making their presence known in the landscape very quickly (re: the Zizea aptera and the Solidago juncea)? Is this a problem? Well, if the starting point for a landscape was a lot of space that needed to be filled in quickly, these species could be handy additions, almost immediately giving the space some real flower power early in the season (re: the Zizea aptera) and mid-season (re: the Solidago juncea). However, within the small space of this garden, they started to feel like something bordering on minor nuisance and I think contributed to a kind of weedy look that at certain points during the growing season I didn’t particularly like.
Had the landscape been in a public setting and thus with an accompanying maintenance plan, I would have recommended some cutting back of certain plants once their flowers were spent (the Zizea aptera in particular, and perhaps some of the Solidago juncea). I also would have recommended cutting back or removing certain taller self-sowing plants (e.g., Asclepias syriaca) that started moving toward/populating the front of the landscape. As the front of the landscape intentionally consisted of lower-growing plants, their presence really did give the sense of a weed invading that space. In a similar vein, if I was to update the landscape again, I would add in even more structural plants than are already there—more Hylotelephiums, more Karl Foerster.
The reworked butterfly landscape in the summer of 2024, documentation of how it has changed over time completed.
Beyond the subject of weediness as an aesthetic, what actual weeding did we have to do? The answer is not much, aside from weeding out a very persistent mint that had been planted in the space years earlier and will probably always be in the space to varying degrees. Had that not been in the space to begin with, the landscape would have required almost no weeding. Of course, the weeding question speaks to a larger challenge with maintenance of such a landscape within a public setting. A certain level of skill and knowledge of plants is basically a requisite for maintaining this kind of landscape. To the untrained eye, especially in late spring when the plants start to emerge, many of these plants will look like weeds. Even once fully grown in mid-summer, many will, to an unskilled garden maintenance worker, look like weeds. And given the sheer diversity of plants in the space, even I wasn’t sure sometimes what certain plants were—especially if they weren’t in bloom or were still newly emerging.
This speaks to one of the reasons why so many nursery cultivars are widely used: to the untrained eye and to low-skilled maintenance crews, they look like they’re supposed to be there. Thus their presence ensures some kind of long-term viability of the landscape and assurance that the investment in it won’t be for naught. Additionally, many nursery cultivars tend to have staying power. Of the cultivars we planted, we only had one casualty—one Karl Foerster. Indeed, I had picked these particularly cultivars not simply for their shape, form, and wildlife appeal, but also because over the years of doing landscape design and installation I had learned that they are virtually foolproof—and now I know from this project that they are foolproof and reliable even with competition from lots of other plants, including some extremely aggressive self-sowers. In fact, this has been one of the most valuable lessons of this project—that these particular plants can really hold their own and stake their claim within a wilder landscape, and that, yes, this overall approach to landscape creation can be a viable one, given, as pretty much all landscapes need, the right infrequent but skilled maintenance.
But beyond the notion that this approach can be a viable option for a kind of hybrid native-/non- landscape creation, my more philosophical hope is that this study of a small but information-rich landscape can serve to underscore how it’s never as cut-and-dried as “all native plants good,” “all cultivars bad.” We live in a world of gray areas, and the plants within our landscapes do too. The aforementioned LA Times opinion piece that extolled the endless virtues of native plants and how if only we plastered LA with them, the city’s ugliness problem would be solved, could have been so much more effective if its starting point had been not “native plants are the only way” but instead the question, How do we soften LA’s increasingly hard edges? Some species of native plants might be part of the answer, but a whole host of sensory-sparking, vibrantly-colored drought-tolerant plants from other summer-dry regions of the world would then be too. Off the top of my head, I can think of umpteen of them. Landscapes and gardens are not an argument to be won but a set of spaces that can stir the senses and spark a larger conversation. Sometimes that conversation will lead from the beauty of the space to larger topics of wildlife and water conservation. Other times, it will simply center on just how lovely and wonderful it is to be in that space, and that is just fine too.
