Breaking the Design Code behind Piet Oudolf’s Entry Garden Walk

Seeing the New Perennial planting at the Toronto Botanical Garden for the first time in 2006 was like discovering a Rosetta stone of modern garden design. The day I saw it, the Entry Garden Walk had been newly planted and the perennial beds looked like an immense puzzle, with each plant poking up its head like a clue.

Ever since, I’ve attempted to unravel the mystery of its making and decode the guiding principles of the garden’s designer. The serpentine journey has taken me into Oudolf’s books and his gardens, and to the Netherlands twice and back.

Seven years on, I’ve come to a far deeper understanding of some of the key principles of naturalistic planting design that Oudolf uses in the Entry Garden Walk (or Piet’s Garden as Horticulture Director Paul Zammit calls it). Here’s some of what I’ve discovered on my journey.

1. Never reveal everything at once

Oudolf makes ingenious use of hedges, levels and plant curtains, or screens, to create an air of mystery that blocks out the outside world and entices the viewer to come inside and explore.

For example, at the TBG, architect Martin Wade has elevated the front of the walkway planting and faced it with a concrete wall to separate it from the parking area. Oudolf has reinforced Wade’s effect of separation with a screen of perennials that masks the mass of plantings behind, so that the full impact of the garden is revealed only when you walk up onto the sidewalk and find yourself completely surrounded by plants.

2. Look and learn from nature

Oudolf’s root inspiration is nature itself. He starts with plant selection, preferring robust and long-flowering plants with a wild character, turning his plantsman’s eye to the proportions between flower, seed head, leaf and stem and to the balance between form and texture.

He places less emphasis on colour, favouring small, less profuse flowers that are akin to their wild cousins. This frees Oudolf from the dictums of colour theory so that he can mix many different colours without much danger of them clashing. The effect is further enhanced by the buffering effect of ornamental grasses.

This is a naturalistic approach that reflects Oudolf’s fascination with how plant communities thrive in the wild — both in terms of ecology and as a guiding aesthetic. Oudolf asks us to look beyond our fixation with flowers to appreciate the full life cycle and drama of the planting itself — in all its four seasons and stages of growth.

In the Entry Garden Walk, Oudolf has abstracted patterns from nature: sweeping drifts of prairie-style perennials are massed into diamonds, scoops and blocks and intermingled with grasses, woody plants and trees to evoke a feeling of nature. And while the planting hums with a spirit of spontaneity, it is, in fact, a highly ordered horticultural and artistic composition.

3. Wild planting in a strong design

The late modernist Dutch designer, Mien Ruys, who was one of Oudolf’s key early influences (along with Germany’s Karl Foerster), cultivated an aesthetic philosophy based on the power of juxtaposition, setting naturalistic plantings within the context of a formal yet modern garden design. Oudolf has evolved this idea by placing his naturalistic plantings within formal garden structures — invariably with a contemporary twist.

The Entry Garden Walk is a good example. The underlying structure is modern: from the curvilinear caged hedges to the flared stone paths, concrete benches, sleek metal trellis work and the sculpture in the garden itself. Within this strong architectural context, the plantings somehow seem all the more wild.

 4. A matter of perspective

Generally, traditional mixed borders are designed for the viewer to look along or at the planting — as in an art gallery. But Oudolf designs from a variety of perspectives and angles, looking into, along, under, through, up or down, over and out of the garden. He brings the viewer right into the planting for a more immersive experience. For example, viewing Piet’s Garden from the west, you look over the plantings and all around you, as in a meadow. This perspective highlights the tapestry of the design to reveal patterns, rhythms and changes in height and depth. As you walk eastward, the garden slopes upwards, and at the top Oudolf has planted tall prairie perennials to accentuate their height and to make us look up to see them.

5. Plant palettes and intermingling

Oudolf organizes perennials into a planting palette of geometric forms, shapes and colours that can be combined in myriad ways. He divides the elemental forms of flowers, and even seed heads, into spires, plumes, buttons and globes, umbels, daisies, screens and curtains. He envisions the colour spectrum as hot, cool, sweet, sombre and earthy. Foliage provides the counterpoint to form and colour by adding layers of shape and texture.

He might pair the contrasting shapes of spires with umbels: blazing star with yarrow, for example. Then, he introduces plume shapes, such as those of astilbe, to connect these contrasting forms, while using the daisy shapes of coneflowers and asters, for instance, to create button-eyed points of definition on the lower levels of the planting scheme.

Piet’s Garden is composed of various groups of shapes that he repeats in different combinations to create rhythm and to punctuate the flow of his composition. He typically uses a roughly 70:30 ratio of taller structural plants to lower-growing filler plants — all closely spaced to achieve a lush meadow effect.

While large blocks of perennials can be dramatic when seen from a distance, they can compromise detail when viewed up close. Oudolf remedies this by using a New Perennial planting technique called intermingling, which is inspired by how wildflowers grow randomly together in nature. When two or three different perennials are paired within the same block they blend into the overall planting when observed from afar, but up close they offer an unexpected level of detail.

In the TBG gardens, such startling intermingled combinations abound, including setting off the blue-grey spears of Perovskia atriplicifolia ‘Little Spire’ against the spiky globes and thistle-like silver foliage of Eryngium yuccifolium. Common in nature, but rare in North American gardens, intermingling offers a new frontier of experimentation in how we combine plants.

 6.  Every garden needs a guiding hand

Last September, I talked about design with Piet Oudolf while visiting his plantasmagorical garden and nursery in Hummelo, the Netherlands. When he asked me how the TBG planting was doing, I replied, “Great, it’s taking on a life of its own.” (I was thinking about the spread of rambunctious self-seeders like Knautia macedonica and grasses like Calamagrostis brachytricha.)

His response was that a guiding hand remains necessary to ensure the integrity of the original design and intention; otherwise things can fly out of control. The role of maintenance is to actively continue the design process, with the freedom to edit the garden selectively as it evolves.

7. Perennials: To cut or not to cut?

When deciding whether to cut back perennials in the fall, traditional gardening says. “Cut them down.” Modern gardening asks, “Do I cut them down?” Oudolf says, “Cut down and you’d miss a lot.”

8. A planting for all seasons

Click on the slideshow below to see how the central meadow planting transforms through the seasons. Five shots taken from the exact same spot in the garden over the course of a year. Brilliant work by guest photog, Janet Davis.

9. The Master’s touch

In our chat, Oudolf emphasized that planting design is about far more than combinations. Like a great orchestral composer or painter, he’s able to visualize the overall composition as a highly complex but unified expression. Like a symphony, the garden is never truly finished until the audience experiences it for themselves.

A Pick of Piet’s Signature Plant Palette

Astrantia ‘Roma’ (‘Roma’ masterwort)
Deschampsia cespitosa ‘Goldtau’ (‘Goldtau’ tufted hair grass)
Echinacea purpurea ‘Vintage Wine’ (‘Vintage Wine’ purple coneflower)
Eryngium yuccifolium (rattlesnake master)
Gillenia trifoliata (Bowman’s root)
Inula magnifica ‘Sonnenstrahl’ (‘Sonnenstrahl’ fleabane)
Panicum virgatum ‘Cloud Nine’ (‘Cloud Nine’ switch grass)
Pennisetum alopecuroides ‘Cassian’s Choice’ (‘Cassian’s Choice’ fountain grass)
Persicaria amplexicaulis ‘Firetail’ (‘Firetail’ mountain fleece)
Pycnanthemum muticum (big leaf mountain mint)
Sanguisorba officinalis ‘Red Thunder’ (‘Red Thunder’ great burnet)
Sedum telephium ‘Matrona’ (‘Matrona’ stonecrop)
Sesleria autumnalis (autumn moor grass)
Sporobolus heterolepis (prairie dropseed grass)
Thalictrum ‘Elin’ (‘Elin’ meadow rue)
Veronicastrum virginicum ‘Adoration’ (‘Adoration’ Culver’s root)

This story was first published in Trellis, the magazine of the Toronto Botanical Garden.

With much thanks for her kind permission: all photography © by Janet Davis.