A day or two ago I was sitting at my desk mulling over which of several blog-posts-in-progress I would work on, when a colleague emailed me a link to the latest post on thinkinGardens. Happy for the distraction, I clicked on the link. If you’ve ever visited this website you know the articles are always thought-provoking and articulately presented – indeed the contributing writers are the intelligentsia of garden design.

This particular post was Part 1 of an arranged discourse, a debate if you will, between Thomas Rainer and Noel Kingsbury, discussing mass planting vs. intermingled planting and which represented the more sound ecology, thus the better design choice. I’d certainly been aware of an apparent paradigm shift – from Piet Oudolf’s compositions of huge single-species drifts, to the new intermingled compositions now being espoused by same designer – but I never really gave it much thought. While I know, as a designer, that it’s important to stay abreast of current trends, I’ve always been of the opinion that good horticulture and good design are timeless and don’t depend on adherence to design trends.

However, after reading Thomas Rainer’s opening argument (excerpted from a previous post he’d published in August), I decided I oughta take this matter more seriously. Judging by the ensuing comments, some of which were very long and impassioned, I figured this must be some really important stuff being discussed here – I’d better jump on one of these bandwagons lest I get left behind. Thing is, I’m not much of a wagon jumper. I’m more of a fence sitter. I know, I know, there’s some old adage that sitting on the fence means having one foot in Heaven and one in Hades – I believe what it really means though, is that I see both sides of the story. Initially I was going to leave a comment with my own thoughts on the matter, but the comment thread was already long and cumbersome. Besides, who am I to argue with, or agree with, or even comment on, the ideas put forward by these big garden thinkers. But comment I will….

Thomas presented a very balanced argument in his article, and I found myself nodding in agreement throughout the eloquently written piece. He suggested that both aesthetics – mass planting and intermingled planting – can have a place in good garden design, since both are seen in nature. And I agree – I think. I am fortunate to live only a few blocks from Nose Hill Park, a huge expanse of natural mixed-prairie grassland. I thought about the masses of native Rosa woodsii, Elaeagnus commutata and Symphoricarpos occidentalis growing in the ravines or along the slopes, and snorted at the thought that anything might intermingle within their dense colonies – a clear-cut case of nature’s mass planting. On another hillside nearby, numerous native grasses, as well as Campanula rotundifolia, Gallairdia aristia, Erigeron caespitosus, Linum lewisii and many other native species, comfortably intermingle. So I guess I must be in Thomas’s not-one-nor-the-other-but-both camp.

I called my sister, hoping she would have some photos to illustrate these points – though not a horticulturist by profession, she has a profound interest in native plants and certainly knows them better than I. We talked about nature’s areas of seeming monoculture and the more we talked the more evident it became that things are not necessarily as they appear – that the forest of evergreens we see along the drive into the mountains may appear to be a single type of tree, but in fact more likely consists of spruce, fir and hemlock. Or that colonizing shrubs like our numerous native rose species may obscure, but not necessarily exclude, smaller flora. Or that it’s possible for the aforementioned roses to coexist in an intermingling relationship with some other equally effective competitor, say Cornus sericea. I remembered a recent post about a cross-Canada road trip, in which I wrote: “I am fascinated by the changing ecosystems or ‘biomes’ as we move from west to east – from Grassland to Parkland to Boreal Forest … as gardeners, landscape designers and horticulturists, we can take many lessons from the natural rock formations and forestation that Mother Nature presents – the way she mass plants her trees and understory, the large areas of perceived monoculture masking the plant diversity that lies therein. Indeed this should be our template.” Hmmm.

Pat started going through her photos as we spoke – she’ll jump at any excuse to do so. A while later she sent a few to me in an email:

“Hi Sue”, she wrote. “Here is one example of both – in my mind. I don’t think Mother Nature likes to be pinned down….

“As the snow recedes high in the mountain meadows, one of the first flowers to appear, especially in avalanche tracts, is the yellow glacier lily – Erythronium grandiflorum. They are quite beautiful en masse and I think they are a great example of a mass planting. However if you look closely, you can see a few small white flowers in amongst them. They are the other herald of spring in the mountains (and most everywhere in Canada for that matter) – the ‘spring beauty’, in this case the Western Spring Beauty, Claytonia lanceolata. This small white flower also emerges as the snow melts and it too can be found en masse, but here is found ‘intermingling’ in a mass planting of glacier lilies – if one looks closely enough.”

Nicely put Sis – thanks.

Looking up the avalanche tract towards the mountain top, a mass of Erythronium grandiflorum in the forefront. Photo: Pat Gaviller

A closer view reveals bits of white amid the yellow. Photo: Pat Gaviller

Zoomed in further ones sees that Claytonia lanceolata grows amongst the Erythronium grandiflorum. Photo: Pat Gaviller

A quick glance might suggest this mass of evergreens is all one type of tree, but the greenery on the mountainside includes western red cedar, western white pine, lodgepole pine, western hemlock, interior Douglas fir, western larch & hybrid white spruce (Picea glauca x engelmannii).
Photo: Pat Gaviller

Alpine meadows are a classic example of plants intermingling in nature. Here a lone clump of Anemone occidentalis blooms alongside Claytonia lanceolata and emerging Antennaria lanata foliage.
Photo: Pat Gaviller

Today I returned to thinkinGardens to read Noel Kingsbury’s response. He too made some valid points, one of which was the very thing my sister and I had discussed relating to monoculture – that “often what appears to be monocultures are not”.

So does this mean then, that I’ve switched camps – that I’ve now bought into Mr. Kingsbury’s intermingling perspective? Maybe. Well, no not really. It’s true one would be hard pressed to find a true monoculture in nature. But mass planting doesn’t equal monoculture – there are mass plantings in nature, and intermingled plantings… and intermingled mass plantings, and massed intermingled plantings. How’s that for sitting on the fence? But there’s more.

Rainer also points out the potential for chaotic and badly executed compositions when using an intermingled approach, and both writers acknowledged the need for informed plant choices if this approach is to succeed. This is of course key – one must know and understand the growth and reproductive habits of any given plant, lest some garden residents crowd others, or shade them, or outcompete them in some way or another. Come to think of it there are plants that would absolutely not fit into an intermingled planting scheme – they would very quickly dominate the composition and begin to mass themselves regardless of the designer’s intent… and it would be completely unnatural to insist that they do otherwise. Noel speaks of “managing competition” and admits that it “requires plant knowledge and experience”. But why, if creating a natural ecosystem is the goal, would “managing competition” even need mention. The bottom line is, the old mass-planting design model and the new intermingling approach both require harnessing nature, which is fine, but obviously neither can claim to be a completely natural design strategy. Which is more natural?  Who knows?  And does it really matter?

So I guess I’m with Thomas here. This where I often stand on many issues – in the middle, on balanced ground. And to be fair, even Noel admitted there was a place for “moments of massing” within an intermingled design. Maybe the two are more in agreement than it first seemed.

I read through the comments made in response to both Rainer’s and Kingsbury’s articles and there were other interesting viewpoints as well, for example, and I’m paraphrasing:

• garden design doesn’t need to perfectly imitate nature’s design.
• it doesn’t matter if you mass or intermingle as long as native plants are used.
• we are losing species at an alarming rate and garden design must be part of the solution to this.
• what we do in our gardens isn’t going save the planet, the bigger picture is more important.

I agree, in part, with all of these positions – no, our garden designs don’t need to be completely “natural”, yes native plant material should comprise a portion of our garden compositions, yes species loss is a concern and should be taken into account when choosing plants, particularly to ensure that pollinators are encouraged, and no the fate of the planet isn’t going to be played out in the garden. Our responsibility as gardeners and garden designers is to create healthy, sustainable ecosystems that are functional and aesthetically pleasing (this is indubitably subjective).

For me, nothing has changed. I’ve always used a mixed approach, with much of the massing occurring as groundcover to create a sort of “negative space”, and the larger plants occupying the positive space – some intermingled, some massed. I’ve never used mass plantings to the extent Piet Oudolf did (though I have to admit I find the huge masses of colour and texture to be breathtaking), and I don’t intend to use exclusively intermingled plantings just because it’s the latest trend. I will continue to design the way I always have, deciding to plant what, where and how-many, based on the site, the plant and my client’s needs. To me this is good design.

Now go mingle or mass or whatever it is you do….

Related articles

• Mingle or clump? by Thomas Rainer (thinkinGardens)
• Intermingling and the Aesthetics of Ecology (Grounded Design)
• Clump or Mingle? by Noel Kingsbury (thinkinGardens)

© Sue Gaviller and Not Another Gardening Blog 2012. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Sue Gaviller and Not Another Gardening Blog with appropriate and specific direction to the original content.