Author Archives: Signe Danler

The Gardens of Piet Oudolf: Pollinator Paradise?

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Flower-filled garden in Oudolf style
Oudolf-designed garden at Pensthorpe, Fakenham, UK. https://www.fiveseasonsmovie.com/gallery/

As part of Master Gardener Week at the end of October, I had the opportunity to view “Five Seasons: The Gardens of Piet Oudolf” and participate in a discussion afterwards. This recently-released film has brought renewed attention to the gardens and landscapes created by this internationally-renowned designer. His popular public garden designs, and several books, have had a profound impact on the design of public spaces, as well as private gardens.

Oudolf’s gardens have been described as spontaneous, immersive and naturalistic, and rely heavily on grasses and structural perennials to maintain visual interest well into the winter. They evoke flower-filled meadows and prairies, and seem at first glance like places that could, indeed, have occurred spontaneously. Oudolf himself acknowledges, though, that they require a certain amount of “interference”, and his design process is comprehensive and very specific. He has a palette of plants that he has tested over time for durability and effect.

During the bloom season, one imagines these gardens will be buzzing with pollinators, and be places of lively, hungry activity. When it comes to pollinators, it seems, almost any garden is better than no garden at all, and a garden doesn’t need to be designed especially for pollinators in order to offer benefits to them. As research in this lab has shown, though, a garden designed specifically to be pollinator friendly has an outsized impact.

So I wondered, how pollinator-friendly are Oudolf’s naturalistic gardens, really?
On the positive side:
• Lots of flowers. From early season to late, things are blooming. Plants are left standing well into winter, providing seed and shelter.
• Little or no use of pesticides.
• Native plants are often included, though there is no particular emphasis on them.

Pollinator friendly flowers
Pollinator-friendly flowers in Oudolf Field, Hauser & Wirth, Somerset, Bruton, UK. https://www.fiveseasonsmovie.com/gallery/

On the negative side:
• Maintenance involves cutting everything to the ground in late winter. This destroys the winter homes of cavity-nesting bees that use the stems. At the Lurie garden in Chicago, this problem was recognized and steps were taken to leave some stems standing.
• Lack of layering. The iconic Oudolf garden is composed almost entirely of herbaceous perennials, with trees and large shrubs lacking. This limits the provision of food and habitat for a variety of creatures.


I believe pollinators could be better supported by Oudolf-style gardens with three simple changes.
• Keep mowed areas to a minimum. Group plants with good winter nesting stems, and leave them standing until they are covered by new growth.
• Include and group small groups of larger plants such as suitable small trees and shrubs.
• Prioritize native plants where possible.

Mowed brown winter garden with a section left standing
Lurie Garden with selected areas left standing for pollinators.
https://www.luriegarden.org/2019/03/15/cutting-back-on-the-cut-back/

If you would like to know more about Piet Oudolf’s gardens, plant choices, and design process, here are some reference materials. And if you get the chance, watch the film “Five Seasons: The Gardens of Piet Oudolf”.

Dream Plants for the Natural Garden by Henk Gerritsen and Piet Oudolf, Timber Press 2000
Essentially a catalog (although not all plants are pictured) of plants that Oudolf has culled to be “reliable plants that, over the years, can be maintained in an average garden without too much in the way of artificial props and bolstering”. Many of them “look good dead”, too. These are the plants he uses in his designs. They are divided into categories of Tough Perennials (the longest section by far), Playful Biennials and Annuals, Troublesome Invasive Plants, and Troublesome Capricious Plants – hardly the usual categories!
If you are an experienced gardener and want an invaluable reference for plants that will enhance your natural garden without requiring loads of work, this book is for you.

Planting Design: Gardens in Time and Space by Piet Oudolf and Noel Kingsbury, Timber Press 2005
On the other hand, if you are not an experienced gardener, this book might be a better place to start. It is a thrifty introduction to the concepts of how gardens fit into nature, and vice versa, and how plants can be used through space – and time! – to create the desired outcomes. There are many lists of plants for specific purposes, such as Small Trees to combine with perennials, and Biennials for self-sowing, and a short but useful section on how to prepare for, implement, and maintain a planting of this sort.

Planting: A New Perspective by Piet Oudolf and Noel Kingsbury, Timber Press 2013
This book builds on the previous two, offering a detailed look at the techniques and philosophy Oudolf uses to design his gardens, as well as specific ways in which he uses plants in them. A season-by-season guide dissects various effects and combinations, and a chart towards the end concisely organizes many of the plants used. One of the most interesting concepts is that of matrix planting.

Several Piet Oudolf books
Several of Piet Oudolf’s books

For more detail on the creation of specific gardens by Piet Oudolf, there are also books on Hummelo, the High Line, and Durslade Farm.

The Self-Sustaining Garden by Peter Thompson, Timber Press 2007
In this book matrix planting is presented in great detail. This is an effective and efficient way of designing intermingled plantings without having to specify the location of each and every plant. The matrix (often grasses) may be made up of several plant species, and serves as a stage for other, showier compatible plants embedded in it.

Dramatic Effects with Architectural Plants by Noel Kingsbury, Overlook Press, 1997
Oudolf’s chief writing partner has produced many noteworthy books himself. As the title describes, this book focuses on plants with strong and dramatic architecture. Having some of these in the mix is a key technique that makes Oudolf’s designs work.

Naturalistic Planting Design by Nigel Dunnett, filbert press 2019
With a foreword by, who else, Piet Oudolf, this is one of the most recent entries in the category of books focusing on natural or naturalistic design. It’s a dense book with at least as much text as photography, covering garden lore from historic, through contemporary, and looking to the future. Basic design principles, as they pertain to a naturalistic design, are also presented, along with a series of case studies illustrated by seasonal photos.

Gardening with Native Plants of the Pacific Northwest by Arthur Kruckeberg and Linda Chalker-Scott, University of Washington Press, 2019.
And finally, if you want to use PNW native plants to achieve Oudolf-like effects in your garden, this recent book is an accessible, thorough, well-illustrated guide to those plants. You will find it easy to browse through for plants that have the look you want. Symbols by each photo give a hint as to each plant’s cultural requirements.

Other resources:
The blog Gardenista has several lovely entries on aspects of Oudolf’s designs. https://www.gardenista.com/posts/?t=oudolf#search
Piet talks about current projects in this recent interview: https://www.hauserwirth.com/ursula/29413-attached-world-piet-oudolf-garden-life

If you want LOTS of pictures to look at, try Piet Oudolf’s Flickr photostream, https://www.flickr.com/photos/10470961@N03/

Or his own website https://oudolf.com/

Pollinators in Your Parking Strip

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What’s the first thing people see when approaching a house? The parking strip.
What is often the ugliest, most barren part of a yard? The parking strip!

The parking strip, often called a “Hell Strip”, is a tough landscaping challenge. Narrowly linear, sun-baked, hard to water, often compacted, subject to foot, dog and other traffic…what self-respecting plant would want to grow there?

This is why parking strip “landscaping” tends to default to lawn, mulch, or gravel.

But there’s another option. For every habitat there are plants to match, so if you want a garden in your hell strip, choose plants that LIKE it hot and dry, and are compact in size. Careful design and plant selection can result in a parking strip that is a beautiful asset, rather than a barren wasteland.

As a bonus, many plants that are suitable for planting in a parking strip are also great for pollinators. There are many Oregon native plants that can thrive in such conditions, and since native plants are generally best for pollinators, why not dedicate your parking strip to growing mostly native plants in a beautiful pollinator garden?

Tips for Success

  • Before making any parking strip plans, be sure to check with your local government (the owner of the parking strip) for any regulations or requirements you need to take into account.
  • Provide a paved landing or path for exiting cars.
  • Don’t obscure utility covers with plants.
  • Before planting, loosen the soil and dig in compost. It can be worth spending a year or two improving the soil, if it is very bad.
  • Plant in fall if possible, to give plants all winter to grow strong roots before having to cope with summer heat and dry.
  • Be patient – it may take some trial and error to find the best plants for your parking strip.

Choose the Right Plants

  • Low water needs
  • Persistent (bulbs, perennials, low shrubs)
  • Compact and tidy form
  • Attractive foliage
  • Variety of textures, shapes and colors
  • Varied bloom times over long season

In Jen’s post a couple of weeks ago, http://blogs.oregonstate.edu/gardenecologylab/2020/03/14/how-do-we-know-what-flowers-bees-like/, she listed flower characteristics that bees and butterflies are attracted to. Here’s a short list of plants that feature these characteristics, AND are good candidates for a parking strip planting.

PNW Native Flowers
Achillea millefolium (common yarrow)
Allium cernuum (nodding onion)
Arctostaphylos uva-ursi (kinnikinnick, bearberry)
Balsamorhiza deltoidea (balsamroot, mule’s ears)
Clarkia amoena (godetia, farewell to spring)
Deschampsia cespitosa (tufted hairgrass)
Eriophyllum lanatum (Oregon sunshine)
Eschscholzia californica (California poppy)
Fragaria chiloensis or vesca (beach or woods strawberry)
Gaillardia aristata (blanketflower)
Gilia capitata (globe gilia)
Iris tenax (tough-leaved iris)
Lupinus formosus (western lupine)
Madia elegans (showy tarweed)
Phacelia spp (phacelia)
Plectritis congesta (Seablush)
Sedum spathulifolium ‘Cape Blanco’ (broadleaf stonecrop) 
Symphyotrichum/Aster subspicatum (Douglas aster)

You can also add compatible non-native plants, that are also attractive to pollinators.

Bulbs for early bloom: Crocus, Iris reticulata, species tulips
Perennials, Low Shrubs, and Ornamental grasses
Achillea ‘Moonshine’ (yarrow)
Callirhoe involucrata (wine cups)
Caryopteris (blue mist shrub)
Coreopsis grandiflora (largeflower tickseed)
Dianthus ‘Allwoodii’, ‘Flashing Lights’ and others (pinks)
Epilobium (Zauschneria) spp (hummingbird trumpet, Calif. Fuchsia)
Lavandula (lavender)
Nepeta cvs (catmint)
Penstemon spp
Perovskia (Russian sage)
Sedum spp
Thymus ‘Elfin’, ‘Archer’s Gold’ ‘Doone Valley’, red creeping

Resources:
“Hellstrip Gardening” by Evelyn Hadden & Joshua McCullough
“On the Verge” by Tracy Byrne www.pacifichorticulture.org/articles/on-the-verge/
Pollinator Parkways Do-it-Yourself Manual

What Exactly is “Garden” Ecology?

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In the Garden Ecology Lab, researchers are studying specific pieces of the garden ecology puzzle, including soil nutrient levels, pollinators, and native plants. But what exactly is “garden ecology”, and why is studying it important?

Let’s start by defining our terms. If you hear the word “garden”, some pretty specific pictures may come to mind, but it is really a very broad term, encompassing anything from pots on a patio to acres of arboretum. A garden is by definition a human-influenced system involving plants, but there are many human-influenced landscapes that are not considered gardens, such as agricultural fields (though gardens may grow food), golf courses (though a garden could include a putting green), tree farms (though many gardens have trees), and parks (though ornamental plants may grow in parks).

Urban vegetable garden

Brittanica defines a garden as a “Plot of ground where herbs, fruits, flowers, vegetables, or trees are cultivated.”  This suggests that the keys are variety and control. A garden is typically composed of a variety of different plants and types of spaces…not unlike a natural ecosystem! In addition, there is the element of control (cultivation). Human choice and aesthetic sensibilities strongly influence what plants grow in a garden. Even a very naturalistic garden has some human-imposed order in it, or it wouldn’t be a garden.

Naturalistic urban garden

Now we get to “ecology”. Ecology is a relatively new natural science, with beginnings in the early 1900’s, when scientists in Europe and the U.S. began to study plant communities. At first animal and plant communities were studied separately, but eventually American biologists began to emphasize the interrelatedness of both communities.1

The word Ecology (originally oekologie) comes from the Greek oikos, meaning “household,” “home,” or “place to live”, so ecology is the study of the relations and interactions between organisms and their environment – the place they live.  Brittanica further clarifies that “These interactions between individuals, between populations, and between organisms and their environment form ecological systems, or ecosystems.”

The study of ecology most often takes place in natural, or near-natural, areas, such as a forest, meadow or mountain. Ecologists study these wilderness environments, searching for guidance on how to restore degraded ones. This reinforces the common concept of nature as being “out there”, far away from where most people live.

Urban ecology studies parks, greenbelts, and forest preserves – the large, public green spaces of a city. But garden ecology? Can something as small as most gardens have an ecology at all? And why should we care?

Well, if you have a garden, and spend much time caring for it, then you are a part of the ecology of that place. Every person who manages a plot of land, however small, is part of the ecology of that land, and all of them together, along with the other people and parts of a city, form the ecology of that city. What is done on those small plots, what grows and lives (or doesn’t) on each one, multiplied by hundreds or thousands or hundreds of thousands of individual plots, has the potential to influence the ecosystem – and the health – of the entire city.

The deeply-entrenched American reverence for lawns means that, at present, the relatively barren landscape of manicured, often chemical-soaked turf is the dominant ecosystem in most cities. Ecologically speaking, such sites don’t contribute much to the local ecosystem.

But that is changing, as more people become aware that a diverse, densely-planted landscape can support a diverse cast of fauna and provide many ecosystem services, including carbon sequestration. This enriches the local ecosystem immeasurably. If this stewardship ethic can be multiplied by even a fraction of the yards in a city, we will begin to see that “garden ecology” is another name for OUR ecology. It is the interrelationship of we humans to the plants and animals, stones and streams, among which we make our homes. It is part of understanding that nature is not just far away, in pristine wilderness. Nature is right here, sipping nectar from your flowers, nesting in your trees, burrowing under your feet and buzzing past your nose.

https://www.piqsels.com/en/public-domain-photo-oluru

1https://www.britannica.com/science/ecology

From the Lab to Your Laptop: Getting Research to the Public

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The members of the Garden Ecology lab spend much of their time on research into subjects that affect, what else, the ecology of home gardens. Pollinators and their relations with native and non-native plants, bee variety and abundance in gardens, and soil nutrient levels, are among the topics they are delving into.

One of the challenges for the lab members – and for all scientists – is how to get the results of their research into the hands of people who can use it. Scientific papers are the traditional way, but not many people actually read those, and it can take a long time for research to trickle out from papers to the general public. If you read this blog, you’ve discovered one of the ways current research is disseminated quickly, and you’re learning new ideas that you may be able to implement in your own research or gardening.

Science you can use in your garden

Another way research gets to the public is through teaching. Lab members present new data in lectures, interviews, presentations, workshops and classes, including OSU Extension’s Online Master Gardener training, which I teach. Each year the course reaches around 40 Oregon MG trainees, plus another 60 or so horticulturally-minded people who take the course simply to improve their garden knowledge. In addition, our single-subject Short Courses are accessed by several thousand people per year. So any new research I can include in these courses can potentially reach hundreds or thousands (depending on the subject) of gardeners per year, who in turn may influence other gardeners.

With this in mind, I have cited Mykl Nelson’s research on excessive nutrient levels in managed vegetable garden soils to caution students about the perils of over-fertilizing. In 2020, my new module on Gardening with Pacific Northwest Native Plants will be influenced by Aaron’s data on the native flowers most favored by native pollinators. His research, plus other research taking place elsewhere, is showing that just planting a garden of pollinator-attracting plants may not be the best tactic to help native pollinators. A garden full of bees is often, really, a garden full of honey bees. What about all the native bees that are less visible, but at least as important? Aaron Anderson’s research into which plant species attract which bee species is beginning to show that the plants most attractive to honey bees are generally not the same as those most attractive to native bees.

Native bee on a native rose
Honeybees on non-native sunflower

The takeaway? Gardeners who want to support pollinators can take the extra step of searching out and growing native plants that are especially attractive to native bees, in addition to the many flowers that honey bees frequent. This is what I will be teaching my Master Gardener trainees in Oregon, and the rest of my students all over the country; many of them will in turn teach other people. Bit by bit the new information gets out there, and more native bees may find the flowers they need to thrive.