Mingle or clump? by Thomas Rainer

October 29, 2013

in Articles, General Interest

This is going to be challenging and interesting, everyone, (get your brains out) and it is just what thinkingardens is for. Recently Thomas Rainer published a post on his excellent blog raising questions in response to Noel Kingsbury and Piet Oudolf’s latest book, Planting, a New Perspective.

I asked him to write us a piece with these questions, and I asked Noel to respond. Both kindly agreed. So the next two posts (Noel’s to follow very soon) comprise this dialogue.

First is Thomas’s challenge.

Anne Wareham, editor

Clearly-legible-patterns-created-by-Blue-Broomsedge-Andropogon-virginicus-var.-glauca-Saw-Palmetto-Seronoa-repens-and-Longleaf-Pine-Pinus-palustris.jpg Thomas rainer for thinkingardens

Clearly legible patterns created by Blue Broomsedge (Andropogon virginicus var. glauca) Saw Palmetto (Seronoa repens) and Longleaf Pine (Pinus palustris)

 Thomas Rainer:

Is intermingling really more ecological? Or just the stylized look of ecology?

Planting design in the last decade has taken a decisive turn toward ecology.  One of the interesting by products of this shift is the rise of mixed plantings in many designed projects.  Piet Oudolf’s work on the Highline in lower Manhattan—now one of the most visited tourist sites in the New York—is a much celebrated example of this trend.  The plantings around the London Olympic Park also use this technique to great effect.

But intermingling plants is not just a design strategy; it is increasingly an ideology. This is most apparent in Noel Kingsbury and Piet Oudolf’s latest book.   ‘Planting: A New Perspective’ is a celebration of the rise of a more intermingled style. Kingsbury has long been an advocate of this mixed planting style, but this latest book positions intermingling as a part of a new international movement. Intermingling is seen not only as a new design trend, but as a way of creating better ecological function. In a recent article in the journal Topos, Kingsbury writes:

Creating intermingling plant combinations, whether aesthetically driven or strictly functional, creates an ecology. In a conventional horticultural planting, plants are discouraged from interacting, but when they do, ecology starts to take over. ” Trends in Planting Design. Topos, 83, 2013

Statements like these raise several questions in my mind: is intermingling really more ecological? Or is it just an aesthetic that imitates ecology? And what about function? Does intermingling plants result in more stable, lower maintenance plantings? Or does it require more intensive gardening to maintain it?

As intermingling becomes increasingly popular, I think it is time to have a robust dialogue about the advantages and disadvantages of mixed planting schemes. I would like to make a few points here.

1. Both intermingled and massed plantings occur in the wild; neither is inherently more natural.

There is a tendency in the literature cited to associate mixed plantings with wild plant communities and naturalism. In a recent blog post, Kingsbury wrote, ” Intermingling is what happens in most natural plant communities. You don’t get a solid mass of plants one here and another one there.”

Actually, I’d argue that solid masses of plants are quite common in natural plant communities.  In fact, as plant communities age, a handful of species tend to dominate. It’s why vegetative ecologists refer to plant communities by the dominant species (Oak-hickory forest, etc.).

Saw Palmetto copyright Thomas Rainer for thinkingardens

Saw Palmetto, massing.

As I write this now, I am looking out a window in a cottage on the American Gulf Coast. Saw palmettos stretch in masses of a half acre or more under a near monoculture of long-leaf pines. It’s stunning and entirely natural. Of course, intermingling is indeed present in most plant communities. Seed-dispersed plants tend to mix themselves with other plantings; clonal plants often create large masses.   Wet, fertile communities are highly competitive and exhibit a high degree of massing; dry, poor soil communities exhibit a high degree of mixing. Neither massing or intermingling is inherently more natural.

When massing is described as that “awful blocky look,” it reveals (to me) more a personal aesthetic preference than a defensible statement about nature. So let’s drop the pejorative language that describes masses of single species as “conventional” or less “natural.”

A population cluster of Liatris paucifolia var secunda Copyright Thomas Rainer for thinkingardens

A population cluster of Liatris paucifolia var secunda

2.  “Ecology is not a value; it is a field of science.”

The term “ecology” is thrown around quite a lot these days, often to describe one type of planting against another.  In a recent email exchange I had with The New York Botanical Garden’s Todd Forrest, he wrote, “Ecology is not a value, it is a field of science.”  He is precisely right. While there are some studies that inform planting design, there is little data to show that one planting strategy is universally more ecological than another. Whether a planting is mixed or massed should not be the standard by which we evaluate ecological quality.

3. Celebrating mixed plantings without discussing its drawbacks has the potential to mislead the uninformed.

My biggest fear when it comes to popularizing mixed plantings is that it will create an abundance of sloppy imitations. Intermingling plants requires a high level of skill and knowledge. It requires an almost intuitive understanding of how plant morphology is related to its competitive strategy—a skill that so few teach, and even fewer understand. A poorly composed intermingled planting (I’ve had more than my share) can be a functional and aesthetic mess.  

In America, many native plant purists have embraced the romantic notion that native plantings should look intentionally un-designed. As a result, there are thousands of miserable-looking native plantings with no discernible design.  For me, these plantings pose a larger threat in that they turn off the larger public from naturalistic design.

Well-designed mixed plantings can be enormously pleasurable; but poorly-designed (or maintained) plantings can send people running to their weedeaters and lawn mowers.  So as we celebrate the potential of mixed plantings, let us make sure we discuss the pitfalls of intermingling. Focusing the conversation on strategies that make mixed plantings more legible and maintainable (matrix planting comes to mind) would benefit us all.

Mixed plantings offer enormous potential for developed landscapes across the world. I personally celebrate Noel Kingsbury’s body of work. No other writer/designer in the English language has done so much to advance our knowledge of naturalistic design. But in our enthusiasm for naturalistic design, let’s not eliminate massings of single species from our toolbox.  Massing may be “conventional,” but in order for designers to create dynamic plantings that can withstand the pressures of urbanization and climate change, we need every compositional tool available.

Thomas Rainer 

Thomas-Rainer portrait    Thomas’s Blog

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