A Conversation with Dan Hinkley

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A month ago I posted in this space about Daniel Hinkley, about his noted collector’s garden in Indianola, Washington, and his new book about it, Windcliff: A Story of People, Plants, and Gardens.  I admired the book – it’s beautiful and well-written – but I didn’t, and don’t, understand the plant collecting impulse that motivates Hinkley.  In the interest of fairness, however, I called Dan Hinkley a couple of weeks ago to get his side of the story.

When I asked him why, with all the plants available to American gardeners, he had to go out into the wild seeking more, he replied with his own question.  Would I ask a chef why with all the recipes now current, we need new flavors?  Fair enough.

Hinkley also noted that his collecting isn’t random. “I’m not a wholesale collector,” Dan stressed.  “I’m not skipping through the woods merrily picking up seeds of anything I see.”  A plant has to strike him as having garden merit, the ability to fill a horticultural niche, for him to collect it.

He’s interested, too, in the role the plant plays in the local environment.  He has, he says, reams of notes documenting the plants he has seen on expeditions, with information about what they were growing with, where and at what altitude (remote mountain ranges have been his favorite collecting grounds).  These notes present snapshots of a time and a place, and sadly may provide the only insights now, as so many natural areas Dan has visited over the last 35 years have been destroyed.

He partially allayed my fears that such importations may introduce invasive plants.  Dan said that he works with botanists at the University of Washington to identify species with invasive tendencies and scrupulously avoids such introductions.

He asserted that transforming six acres of mowed turf, what his property was when he purchased it, into a dense complex of foliage and flower, has benefited local pollinators and wildlife.

This is where I still part company with Dan and other plant collectors.  For them, such ecological benefits are a by-product.  For me, they are increasingly the point of gardening, and I know that they can be much greater if you focus on the cultivation of locally indigenous species. Windcliff is picturesque, but from the perspective of an ecologist or an environmentally oriented gardener, not particularly functional.

Click here to listen. to the rest of my conversation with Dan Hinkley.

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My father was a compulsive tree planter, but it was my mother who taught me the finer points of gardening.

Her homeschooling was followed by two years in the New York Botanical Garden’s School of Professional Horticulture, and then ten years as horticulturist at an Olmsted Brothers designed estate on the Hudson River Palisades.

I’ve worked as a horticultural journalist for 35 years, contributing to publications ranging from Martha Stewart Living to the Journal of the Royal Horticultural Society and The New York Times.  My most recent book is Nature Into Art: The Gardens of Wave Hill, which is a tour of the lessons to be learned from that great public garden.  I’m currently focusing on my new podcast (at thomaschristophergardens.com) which features weekly interviews with leaders of environmentally-informed gardening.

My special enthusiasms include sustainable gardening, especially sustainable lawns;  heirloom chicken breeds; and recreating vintage New England hard ciders.

 

Contact Tom by email

29 COMMENTS

  1. Experts are increasingly saying that to keep our environments healthy and resilient it is more about he diversity of plant species rather than just indigenous species alone. Native species are an i.mportant starting point but including other non-native plants provides many benefits too

      • Well, assuming we’re talking about the benefits of combining native and non-native plants in gardens and public space designed landscapes vs. ecological restorations… here are some excellent resources in terms of specifics (apart from Google, of course):

        For starters, Prof. Linda Chalker-Scott of the Garden Professors has explored this topic at length: http://gardenprofessors.com/native-vs-exotic-not-simple-seems/

        The Royal Horticultural Society (RHS) in the UK has conducted a comprehensive and ongoing multi-year ‘Plants for Bugs’ project in partnership with the University of Sheffield, which concludes the following (in a nutshell):
        “Most importantly, any planting in a garden is better than none for invertebrates and diversity of plant origin in a garden is a strength, not a weakness.”
        https://www.rhs.org.uk/science/conservation-biodiversity/plants-for-bugs

        This in-depth scientific article from Stephen Head in academia.edu, also comes out in support of an expanded concept of plant species diversity to maximize biodiversity: https://www.academia.edu/36259942/What_is_the_relative_value_for_wildlife_of_native_and_non_native_plants_in_our_gardens?email_work_card=title

        My particular interest is planting design – so, to gain a more biogeographical planting perspective for amplifying biodiversity in designed landscapes, I’d recommend reading ‘Sowing Beauty: Designing Flowering Meadows from Seed’ by renowned horticultural ecologist Prof. James Hitchmough, who headed up the LA program at the University of Sheffield.

        On a macro-level, here’s another interesting paper (there are many more on specific sub-set topics): https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.2005568

        Back to North America, I’ll assume you’ve read the groundbreaking book ‘Rambunctious Garden: Saving Nature in a Post-Wild World’ by environmental writer Emma Marris.

        Lastly, I visited Windcliff for the first time two years ago in the late fall on a trip to the West Coast. I’m not usually a big fan of collector-style garden either but I thought Windcliff far transcended the sum of its parts, perhaps because of the designer’s skill at creating a unified holistic environment in a kind of world garden filled with multitudinous forms, textures, and structures. Did you have the chance to actually visit?

        For my part, I’m deeply appreciative that such a place exists. Thanks for sparking the discussion.

        • One thing that both Dr. Chalker-Scott’s work and the BUGS study from the UK seem to gloss over is plants as larval food sources. Dr. Chalker-Scott’s work is primarily a survey of existing literature and not primary research, and the literature (along with the BUGS study) does say that diversity of forms and long-flowering time will support 80% as many pollinators as a strictly native garden, so nearly as effective if you plan properly, but still with some gaps (particularly with regards to specialists and larval host plants).

          That said, I’m not a purist, and I’m all for cosmopolitan plant communities. I think it’s much more interesting to ask how a plant relates to its ecosystem rather than to worry about where it comes from. The science is far from black and white, but does seem to stress the importance of including and supporting indigenous plants, which I still hope we can do while acknowledging the contributions and importance of immigrant ones.

  2. As the climate alters ‘local indigenous species’ may well prove less resilient and not necessarily the best choice. It’s better to base the choice of plants on the local micro-climate/soil and build a community of self-sustaining, reliable plants – regardless of origin. Provided the plant will not cause harm to the wider environment, any plant from a similar temperature zone that can be successfully used, should be.

    • There are a couple. of schools of thought on that. Plants from exotic locations do not, typically sync with indigenous mycorrhizal fungi, nor do they offer similar benefits to local pollinators, so they don’t really form a true functioning community. If you want to practice assisted migration, which is what you seem to be alluding to, you are better to seek plants from nearby but warmer zones, because they are more likely to fit with the local wildlife. I included a very interesting interview with an invasion ecologist about this topic on my podcast a few months ago.

      • Really? I garden on Vancouver Island, on the west coast of Canada, and the local bee species seem completely in sync, not to mention in love, with the the thyme, echinops, salvias, eryngiums and agastaches in my garden – none of which is an indigenous specie. I can’t speak to their relationship with the local fungi, but the plants (and the bees) seem to be prospering so I’m going to hazard a guess that the flora, fungi, bacteria and insects are all getting along together just fine.

  3. Recent studies focusing on nightime moths as pollinators have established that they are as important as bees – In fact the plants bees leave, tend to be pollinated by the moths. This is an emerging field of study, but science is leaning towards a diverse mixture of native and non-native plants as the most ecologically beneficial. In my recent book ‘Grasses and Perennials – Sustainable Planting for Shared Spaces’ I suggest that the term ‘exotic’ is rather a prejudicial word, implying inferiority and danger; which is why I prefer the term native, and non-native.

  4. Interesting about the moths. Your assertion about a mix of natives and non-natives being most beneficial is in direct contradiction of studies carried out by Douglas Tallamy at the University of Delaware and Dr. Desirée Narango at the University on Massachusetts Amherst. I would appreciate it if you would share references to the research you are referring to — I would be very interested in reading it.

  5. Very interesting about the moths. Your assertion about a mix of natives and non-natives being most beneficial is in direct contradiction of studies carried out by Douglas Tallamy at the University of Delaware and Dr. Desirée Narango at the University on Massachusetts Amherst. I would appreciate it if you would share references to the research you are referring to — I would be very interested in reading it.

  6. Where do Camels Belong? is an interesting book on our outlook about what is native and what belongs where. Pelargoniums are everywhere today. I’m not the least bit interested in a garden as only an environmental statement. It is a human-made creation and I’m the human mixing things up.

  7. Hi Thomas,

    Thank you for all your work., I have you newest book on my buy list and look forward to reading. There is a lot of vigorous debate among scientists about native vs. non-native. Sometimes, the perspective is different depending on your field of expertise. Here is a literature review that examines native and non-native woody shrubs. I encourage you to read it. https://www.researchgate.net/publication/281751812_Nonnative_noninvasive_woody_species_can_enhance_urban_landscape_biodiversity

  8. Hi Thomas,

    I have your book on my ‘buy list’ and look forward to reading it.

    There is a lot of disagreement among scientists about native vs. non-native. Some of the disagreement stems from which discipline you’re in and some stems from how convinced you are of broad conclusions from very narrow studies. I encourage you take a look at this literature review examine native and non-native woody shrubs. https://www.researchgate.net/publication/281751812_Nonnative_noninvasive_woody_species_can_enhance_urban_landscape_biodiversity

  9. I have your book on my ‘buy list’ and look forward to reading it.

    There is a lot of disagreement among scientists about native vs. non-native. Some of the disagreement stems from which discipline you’re in and some stems from how convinced you are of broad conclusions from very narrow studies. I encourage you take a look at this literature review examine native and non-native woody shrubs. https://www.researchgate.net/publication/281751812_Nonnative_noninvasive_woody_species_can_enhance_urban_landscape_biodiversity

  10. Here’s are some of the many studies that find that insects (and therefore birds) are best served by a diverse landscapes of both native and non-native plants:
    • Professor Arthur Shapiro (UC Davis) reports that “Most California natives in cultivation are of no more butterfly interest than nonnatives, and most of the best butterfly flowers in our area are exotic.” His Field Guide to Butterflies of the San Francisco Bay and Sacramento Valley Regions (University of California Press, 2007) reflects a lifetime of observation and study of butterflies.
    • Professor Dov Sax (Brown University) compared insects living in the leaf litter of the non-native eucalyptus forest with those living in the native oak-bay woodland in Berkeley, California. He found significantly more species of insects in the leaf litter of the eucalyptus forest in the spring and equal numbers in the fall. Professor Sax also reports the results of many similar studies all over the world that reach the same conclusion. Dov Sax, “Equal diversity in disparate species assemblages: a comparison of native and exotic woodlands in California,” Global Ecology and Biogeography, 11, 49-52, 2002.
    • The California Academy of Sciences finds that several years after planting its roof with native plants, it is now dominated by non-native species of plants in the two quadrants that are not being weeded, replanted and reseeded with natives. Their monitoring project recently reported that there were an equal number of orders of insects found in the quadrants dominated by native plants and those dominated by non-native plants.
    • Jennifer Owens (Ph.D., University of Michigan) reports 30 years of observing her garden in Wildlife of a Garden (Royal Horticultural Society, 2011). She found that non-native species were better as food plants for moth larvae than native species. Moth larvae used 27% of the native species in the garden as food plants, and 35% of the alien plants.
    • Gordon Frankie (UC Berkeley) recommends planting a diverse garden that prolongs the blooming period to benefit bees. California Bees and Blooms: A Guide for Gardeners and Naturalists Paperback – October 1, 2014
    • John Marzluff (U of Washington) recommendation to gardeners who want more more birds in their garden is: “Foster a diversity of habitats and natural variability within landscapes.” Welcome to Subirdia,” Yale University Press, 2014
    • The Royal Horticultural Society conducted a study of plant and insect interactions in their experimental gardens that concluded: ”In your garden the best strategy for gardeners wanting to support pollinating insects in gardens is to plant a mix of flowering plants from different parts of the world.” https://www.rhs.org.uk/advice/profile?PID=970
    Thanks for asking.

  11. Here’s are some of the many studies that find that insects (and therefore birds) are best served by a diverse landscapes of both native and non-native plants:
    • Professor Arthur Shapiro (UC Davis) reports that “Most California natives in cultivation are of no more butterfly interest than nonnatives, and most of the best butterfly flowers in our area are exotic.” His Field Guide to Butterflies of the San Francisco Bay and Sacramento Valley Regions (University of California Press, 2007) reflects a lifetime of observation and study of butterflies.
    • Professor Dov Sax (Brown University) compared insects living in the leaf litter of the non-native eucalyptus forest with those living in the native oak-bay woodland in Berkeley, California. He found significantly more species of insects in the leaf litter of the eucalyptus forest in the spring and equal numbers in the fall. Professor Sax also reports the results of many similar studies all over the world that reach the same conclusion. Dov Sax, “Equal diversity in disparate species assemblages: a comparison of native and exotic woodlands in California,” Global Ecology and Biogeography, 11, 49-52, 2002.
    • The California Academy of Sciences finds that several years after planting its roof with native plants, it is now dominated by non-native species of plants in the two quadrants that are not being weeded, replanted and reseeded with natives. Their monitoring project recently reported that there were an equal number of orders of insects found in the quadrants dominated by native plants and those dominated by non-native plants.
    • Jennifer Owens (Ph.D., University of Michigan) reports 30 years of observing her garden in Wildlife of a Garden (Royal Horticultural Society, 2011). She found that non-native species were better as food plants for moth larvae than native species. Moth larvae used 27% of the native species in the garden as food plants, and 35% of the alien plants.

    Thanks for asking.

  12. More studies:
    • Gordon Frankie (UC Berkeley) recommends planting a diverse garden that prolongs the blooming period to benefit bees. California Bees and Blooms: A Guide for Gardeners and Naturalists Paperback – October 1, 2014
    • John Marzluff (U of Washington) recommendation to gardeners who want more more birds in their garden is: “Foster a diversity of habitats and natural variability within landscapes.” Welcome to Subirdia,” Yale University Press, 2014
    • The Royal Horticultural Society conducted a study of plant and insect interactions in their experimental gardens that concluded: ”In your garden the best strategy for gardeners wanting to support pollinating insects in gardens is to plant a mix of flowering plants from different parts of the world.” https://www.rhs.org.uk/advice/profile?PID=970
    Thanks for asking.

  13. Interesting — there’s also persuasive, peer-reviewed science on the other side. Dr. Desirée Narango (formerly with the University of Delaware, now with the University of Massachusetts Amherst) and Dr.Douglas Tallamy of the University of Delaware did a painstaking study with the Smithsonian Migratory Bird Center of Carolina Chickadees and their breeding success in habitats with varying amounts of native plants and found that the birds could not maintain their populations when the percentage of natives was less than 70 percent, due to a drop in native insect populations. It was published in the Proceedings of the National Academy of Sciences, a very prestigious journal. I’ll be posting an interview with Dr. Narango on my Growing Greener podcast (see the link above) in a couple of weeks.

    • In “Native plants improve breeding and foraging habitat for an insectivorous bird,” Tallamy and his collaborators conclude, “We demonstrate that residential yards dominated by nonnative plants have lower arthropod abundance…that function as population sinks for insectivorous birds.” The data provided do not support such a broad generalization. They studied one species of bird, in one geographic location, in a short period of time. They inventoried arthropods for two years in a single month time-frame. They quantify only one variable (plant foliage biomass) in addition to the nativity of plants, the abundance of insects, and the breeding success of one bird species. They have not taken into consideration intervening variables such as variations in temperature, rainfall, pesticide use, etc. The bird species studied is abundant within its range. Its conservation status is “Least Concern.” The abundance of this bird species does not justify the dire predictions of Tallamy’s study.

  14. “The insistence by some designer’s on using solely native plants, is effectively a determination that a given moment in time (usually in the past), is somehow ecologically superior – and overlooks the positive and scientific arguments for planting non-natives. There is little point constructing plantings based solely on region of origin, rather than usefulness and resilience. Plant communities alter all the time and nature is never static; and the definition of native plants is also somewhat subjective – we cannot know for certain how plants were moved and used by early humans. Can we safely assume that a plant is native to a given environment, simply because a plant hunter happened to discover it there – probably quite recently in terms of our evolution?’
    A quotation from ‘Grasses and Perennials – Sustainable Planting for Shared Spaces’.
    What is a native plant? Virtually every landscape we see today is a result of some form of agricultural management, even those we perceive as natural.

  15. Good discussion. I’ll add that I’d like to see research results cited from more than just Tallamy, whose name and publications we’re familiar with. I’m truly interested in reading more research findings that support the natives-only position if they’ve been published. Susan

  16. In Brughardt’s work, we come full circle back to Tallamy’s work. They co-authored this study: “Non-native plants reduce abundance, richness, and host specialization in lepidopteran communities” by Karin Burghardt, Doug Tallamy, et, al. (Ecosphere, November 2010).

    The Burghardt/Tallamy study is a laboratory experiment in the sense that it creates an artificial environment by planting a garden in which it chooses the plant species and then inventories the insect visitors to the garden. In one garden, native plant species were paired with a closely related species of non-native plant in the same genus (called congeners). In another, distant garden, native plant species were paired with unrelated species of non-native plants. The insect visitors that were counted are specifically the larvae stages (caterpillars) of lepidoptera (moths and butterflies). The adult stage of the caterpillars (moths and butterflies) were not inventoried, nor were members of the other 28 insect orders.

    The inventory of caterpillars was conducted over two summer months in 2008 and three summer months in 2009. Findings were very different in the two years of the study: “We found no difference between the total Lepidoptera larvae supported by native plants and their non-native congeners in 2008, but found over three fold more larvae on natives in 2009. In 2008 there was no difference in the abundance of generalists on native and non-native congeners, but natives supported more than twice as many generalists as non-natives in 2009.” Similar results were reported for species richness (number of different larvae species). When paired with unrelated non-native plants, caterpillars showed a significant preference for native plant species, as we should expect because the plants were not chemically similar.

    The Burghardt/Tallamy study does not contradict the findings of Professor Art Shapiro because Professor Shapiro is studying butterflies (not moths) in “natural areas” that have not been artificially created by choosing a limited number of plant species. In other words, the adult and larvae stages of butterflies that Professor Shapiro studies have more options, and when they do they are as likely to choose a non-native plant as a native plant for both host plant and food plant. You might say, Professor Shapiro’s study occurs in the “real world” and the Burghardt/Tallamy study occurs in an artificially created world.

  17. There are too many variables to make a blanket statement either way. I’ve read sources that say butterfly/pollinator preferences vary “by location”. So in New Jersey, swallowtail butterflies may go wild for garden phlox, whereas in Kansas their first preference is pleurisy root butterfly weed, then second choice phlox. I also saw for myself the preference of white lined sphinx moth larvae for my pentas versus native weeds (which I transferred them to once I found one eating those particular weeds). I never even saw any of those cat’s before, this year must have been ten or more. I found it particularly galling that they most enjoyed crawling to the stem ends and eating the actual flowers, then back down the stem for leaves. Anyway, I just try to find a middle ground, mostly natives/nativars, some non-natives, and learn as I go. I think we all would do well to go down that path.

  18. The need for an all-native garden to support local birds and insects is due to habitat loss. A garden of non-invasive exotics in a wide sea of unspoiled native plants and old growth forest is not a blight.

    However, seven and a half billion humans are busily destroying habitat and thereby destroying all the species supported by that habitat.

    The root cause is human overpopulation. One may put a finger in the dike by a planting a wildlife-supporting garden, but in the larger scheme of things, having fewer or no human children is other species best hope for survival as well as our own.

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