Supernaturalistic: The New Perennial Pond Garden

At its roots, the New Perennial movement in naturalistic planting design is about making gardens in symbiosis with nature. It calls for a wilder aesthetic, attuned to ecology, and informed by horticulture.

Inspired by naturally occurring habitats, such plantings are designed landscapes composed of a series of interwoven plant layers together forming a community, abstracting the patterns and rhythms found in nature.

There are no rules, only guidelines for the home gardener: Reduce garden inputs, recycle garden outputs; design with biodiversity & maintenance in mind; group plants by common habitat; work with the conditions you got; invite spontaneity; use plants as a living mulch to cover ground; come fall, leave plants to stand and amend in their own debris; above all, experimentation is the key to learning.

With all this in mind, welcome to my 2020 version of Wildscaping at home.

Myth busting

Let me explode a few myths right off the top. Firstly, that the New Perennial style only really works in full-sun meadow-style plantings like The High Line or Chicago’s Lurie Garden, seen here.

Dutch godfather of the movement, Piet Oudolf finds this oddly amusing because while he appreciates the public response to his prairie-inspired work, he’s equally adept at designing shady woodland plantings or whatever else comes up on his plate. His recent project for iconic restaurant Noma in Copenhagen featured pop-up plantings using a design palette of edible grains and annuals.

There’s also the notion that this plant-driven approach for public space does not translate well to small home gardens. To this, Piet shrugs and responds that it’s simply a matter of scaling down the numbers of plants and groupings; the same basic design principles and plant relationships apply, albeit with a finer eye to detail.

My own experience supports it: I spent well over a decade experimenting with the New Perennial approach in a smaller-scale uncottage garden with diverse microhabitats in sun and shade and it evolved way beyond expectation.

In my first design project at our log cabin on the Niagara Escarpment here in Ontario, Canada started in 2015, I’m working on a far bigger and more complex canvas with a mix of shady woodland edge, riparian meadow, and a small bog to boot, all on the western bank of our one-acre pond. 

Pond Life: Planning + Process 

It’s fair to say my pond garden is the apotheosis of everything I’ve learned to date, culled from all my experience, reading, travels, and conversations.

My plans and plant lists have been crazy ambitious, all to create a supercharged slice of woodland garden plugged into the greater ecosystem here. Of course, much like writing, none of that ambition should be visible in the garden itself.

This project started in my imagination – brainstorming to find a theme for the garden. I wanted something wild-ish, otherworldly, unexpected: a hidden place with a charged atmosphere connected to the greater scale of pond, forest, sky.

On a parallel track, I conducted a site analysis to understand the local ecology and conditions: 

Mono Habitat Profile

• Habitat: Riparian woodland edge
• Projected Planting Area:  Approx. 120 m2
• Hardiness Zone: 4b with ample winter snowpack
• Light: Facing east and southeast. Part sun to dappled shade
• Soil: Organic content 7.8 (high) Dumfries loam
• Moisture: Transitions from dry upper slope to moist to saturated soil
• PH Level: 7.6 (moderately alkaline)
• Local Wildlife: Rich insect life, dragonflies, amphibians, birds, waterfowl, bats, beaver, muskrat, porcupine, mink, coyote, fisher, rabbit, squirrels, raccoons, voles, and the occasional deer

Seeking to balance ecological and thematic factors, I spent the better part of a whole winter researching my dream plant list while wondering how to develop a series of interlaced plant communities.

The Oudolf effect

I was fortunate to have a ringer in the wings.

I’ve long admired how Piet Oudolf artfully juxtaposes the wilder and more controlled elements of his plantings – the presence of one amplifying the degree of the other. I’d traveled to the Netherlands in summer 2013 for a masterclass design workshop with Piet and Nöel Kingsbury at Hummelo. The experience changed my life and we became good garden friends.

When I later mentioned to Piet my plans for a new garden, he kindly offered to advise me, should I wish. It was impossible to refuse such an offer and so, after weeks of working up a succession of plans on tracing paper, I emailed the best of them to Piet in Hummelo for what he called “a proper look”.

My initial plan contained three different matrix plantings situated to match varying moisture levels down the slope along with a succession of bloom times from spring till fall. The matrices were contrasted by tall blocks of waterside perennials and a bog garden.

Over a two-hour Skype call, we discussed my plans in detail, which turned into a far-ranging conversation about Piet’s design evolution, current projects, and of course, plants.

It switched another light on in my brain – allowing me to see beyond combinations and clusters to visualize a bigger picture – how entire areas of the planting can interrelate, like islands in a matrix stream. Piet emphasized the power of restraint, to open up sight-lines and lower the plant heights through the heart of the garden to create the feeling of greater space.

My initial drawings were perhaps overly neat and polite. Where I’d drawn clean lines between sections, he suggested to blend one matrix into another to emulate the intermingling found in natural habitats.

After our chat, I reworked my drawings from scratch. The next version was still wildly ambitious but with a new sense of flow. When I sent it back to Piet for review, his overall comment was – Fast learner!

Matrix stratagems

Typically, a matrix planting consists of one or two quiet grasses, ferns or perennials to form a tightly knit base layer through which the rest of the planting can emerge. It’s an incredibly useful base approach adaptable to virtually any scale garden. 

I put my own spin on it to create a complex succession matrix – using 4-6 different plant species, modelled on the principles of plant sociability and succession.

Much like people, plants are social beings. Some are loners, while others love company.

The idea of plant sociability revolves around how different plants occur in their native habitat – whether as solitary specimens, in small random clusters, mid-sized groups, or larger colonies. In each instance, the plants are completely adapted – everything from roots, to foliage size, and flower – to collectively fit a specific niche within a greater community and ecosystem.

For planting design, sociability provides a major clue towards effectively using a given plant consistent with its nature – and also how to integrate related species of plants within the same plant community.

The idea originates in German ecological theory but there’s an aesthetic aspect as well. A given planting will simply look and feel more natural when you’ve done your homework on how various plants prefer to grow together.

It also takes into account how the members of a given planting will fill in and grow into each other over time.

When developing a matrix involving multiple species, it’s helpful to think in terms of ratios based on sociability and how the various plants will compete amongst themselves. Piet Oudolf will often note the matrix ratios in his plans; for example, a shady woodland matrix might be roughly 40% ferns: 25% sedges: 35% ground layer perennials (BTW: He would specify all the actual plant choices.)

Planting for succession

The second part of the equation is succession to ensure multi-seasonal interest – how you can stage the planting to perform and flower throughout the growing year. It’s a core aspect of not only more traditional garden styles but ecological science as well.

In my own woodland setting, there is an emphasis on spring bloomers but I also want to have something else going on throughout the summer and into the fall.

For example, my shady woodland matrix running down the slope is comprised of intermingled clusters of spring blooming natives: Phlox divaricata ‘Blue Moon’ and ‘May Breeze’, Tiarella wherryi, Chrysogonum virginianum, all creating groundcover along with groupings of the fern Adiantum pedatum for continuity, and Aster divaricata ‘Eastern Star’ for prolific fall bloom.

I’ve also scattered in Uvularia grandiflora, Porteranthus trifoliatus, a few stately Thalictrum rochebruneanum, and all kinds of bulbs from species tulips, Allium ‘Mount Everest’, Camassia leichtlinii, Leucojum aestivum ‘Gravetye Giant’ and Nectaroscordum siculum. It’s my spin on a deciduous native woodland heightened and abstracted, without a hosta in sight.

Meadow matrix melodies

My damp meadow grass matrix (#1) winds through the more open centre of the garden in mid-summer.

Its grassy base is the luminous, Deschampsia caespitosa ‘Goldtau’ interplanted with the magenta plumes of Astilbe chinensis ‘Purpurlanze’ for structure. These are supported by spontaneous bursts of Astrantia major ‘Claret’, Lobelia siphilitica, the red thimbles of Sanguisorba officinalis ’Tootsee’ (sourced from Free Spirit Nursery in B.C.) and umbellifer Selinum carvifolium framing the path’s edge. 

I like to weave jewels in and amongst the matrix and the damp conditions have proven ideal for a lush stand of Veratrum nigrum, which took five years to bloom from seed and  flowered this year with scatterings of Digitalis ferruginea, Campanula glomerata ‘Joan Elliott’ and a few mature specimens of dark-leaved Cimicifuga (aka Actaea simplex).

 

A now signature element was here long before any garden: Equisetum arvensis is a native thug of unstoppable force that thrives on disturbance. But it’s been on the planet for 400-million years and I’ve decided to embrace rather than curse it. Horsetail fills the gaps on the groundcover level, unifies the planting, and shimmers like diamonds in the morning dew.  

I’m also accepting of the native asters that fly in from the pond margins (mostly Symphyotrichum ericoides) but I keep a watchful eye on the progress of cattails (Typha latifolia) and Red-Osier Dogwoods (Cornus sericea) that creep in from the edges. I draw the line at our native Solidago canadensis and pull it on sight, which is super aggressive in a garden context. While a valuable pollinator and host plant, it dominates all the meadow areas of our property and indeed, much of the surrounding  countryside.      

The life aquatic

I found over time that the varying gradations of moisture in riparian plantings can be very tricky to read. The oxygenation levels that determine what thrives or drowns can change within the course of a few footsteps.

Much plant literature talks deceptively about moisture-loving perennials that require “moist but well-drained soil” but what is that really? Well, it’s probably either sandy loam with a high water table or the conditions you find alongside fast-moving mountain streams where plants are immersed in water and oxygenated at the same time.

Great news if you live in the Alps.

My third matrix skirts the edge of the pond with perennials adapted to thrive in wet ground, prone to occasional flooding. Here I’ve mixed prolific self-seeders red, white and blue Lobelias (L. cardinalis, L. siphilitica, L. ‘Alba’) intermingled with the wetland Carex bromoides, and drifts of Iris versicolor.

More structural wetland plants include Flipendula rubra ‘Venusta’, Eupatorium ‘Reisenschirm,’ the giant fern Osmunda regalis, Darmera peltatum, Chelone glabra, all happy with wet feet.

 

Wherever one matrix crosses into another, I’ve blended them together to abstract the edges, which creates yet another set of possibilities for the garden to grow into itself.  

I’ve put Piet’s advice into action and continue to make adjustments along the way to modulate the flow of the design. I’m increasingly able to see and perceive how all the various parts of the planting interconnect in ways that would escape the casual visitor.

It’s far more though than just a living experiment in planting design. The pond garden now creates its own charged atmosphere and emotionality, attracting an astonishing diversity of life to what was previously neglected space.

Next year, it will be open from time to time for all curious and like-minded souls visitors to experience for themselves.

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Note: This story was originally published in the 2020 edition of The Prairie Garden from Manitoba in Western Canada.  It was also translated into both Japanese and German and published in the March 2020 issue of Gartenpraxis, Germany’s leading horticultural magazine.