Clump or Mingle? by Noel Kingsbury

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Now, after all that discussion and noise in response to Thomas Rainer’s piece about intermingling planting, here is Noel’s reply to Thomas. (and sorry, he hadn’t read all your comments before writing it..)

I must apologise to all those who deplore my (quote) “relentless puffing of Veddw garden everywhere you can, especially on thinkingardens” but it appears that Noel has now joined in….

Anne Wareham, editor and Puffer.

Noel Kingsbury:

Intermingling is inspired by natural plant communities, the free, uninhibited way wild plants grow, densely intermeshing, leaning on each other (or is it supporting each other?), often growing so closely together that separating them requires getting down on hands and knees and literally tearing them apart. Intermingling is an inevitable part of the density with which plants grow, often hundreds per square metre.

Compare this with the typical garden border, where about nine plants share a square metre and barely touch each other. Getting down to really examine how wild plants grow can be a revelation, a fascinating experience in the appreciation of the intense struggle for space that goes on at ground level, and in how complex and multi-layered the micro-habitats are down there. The garden seems almost sterile by comparison.

I think this is a good starting point to think about planting design – this huge difference in density between the natural and the designed. It is one reason why maintaining the conventional designed planting often involves so much work.

I’m grateful to Thomas for his support for myself and Piet and our work, and for so intelligently discussing our ideas. There are a few things he says I would like to pick up on.

“But intermingling plants is not just a design strategy; it is increasingly an ideology.”

Yuk. You mean like Marxism-Leninism or Neo-liberalism? Be careful with words like that! Ideology is exactly what my support for mixed planting strategies is not. In planting design and in landscape design and horticulture more generally, pragmatism is vitally important. We have to start from where the world is and where people are, not from where we would like it and them to be. Intermingling will work in some situations and not others. A lot of that is to do with how it will be managed.

Ideology, schmology

Ecology, unfortunately, has become an ideology, a value system, with political ecology muddying the waters with ecology the science. This has been disastrous for both ecology as a science and for environmentalism. The debate over global warming is the awful example, of a problem that needs technical solutions but which very soon became the focus of a quasi-religious neo-puritan ‘ecology’ movement – very much an ideology and a dogma; the reaction – of big oil funded right-wing global warming scepticism, was therefore inevitable. The resulting inability to have a sensible discussion about this huge issue could be our undoing as a species.

This muddying of the clear blue water between value and science has not been helped either by Dough Tallamy and his rather tendentious book Bringing Nature Home: a good case near to ruined by some bad science and evangelical attitude.

No, intermingling is not an ideology. There will be no 4.00 am knock on the door and no re-education camps for garden designers who block plant Lonicera nitida.

Creating ecologies

In taking my quote from Topos, (= “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) about “creating an ecology” Thomas raises an interesting point, which needs elucidating.

Putting plants together and letting them get on with it, as opposed to intervening every time Monarda ‘Piet’s Perfection’ starts to overrun Chamaenerion ‘Wareham’s Wonder’ (btw. I’d better say I am making these names up – before all the plant-nerds go rushing to the RHS Plant Finder) does just that, it creates a dynamic of interaction, i.e. an ecology. BUT just because we now have the e-word, does not mean that we have something more supportive of the local lesser-spotted mason bee (made that up too). In creating intermingling planting ‘systems’ we are creating artificial ecosystems, but the degree to which these support local wildlife does not necessarily follow.

The extent to which intermingling will support biodiversity will depend on what services the plants can supply: food, roosting, nesting etc. As the Sheffield BUGS project has shown, garden plants can supply a great deal, and they do not need to be local natives (although some specific plant species may help support some particular insects).

Whether intermingled plantings are inherently more supportive of biodiversity remains to be proven – I am not making claims I cannot substantiate. Likewise the extent to which they will prove more stable in the long term remains to be proven. I would however suggest that on both counts they probably will – wildlife thrives on diversity, and complex, multi-layer habitats will inevitably provide more habitat than monocultural blocks.

A key concept here (beware, teacher mode taking over) is the niche, which can be thought of as a micro-habitat, and the more different plant species per unit area you have, then the more niches for invertebrates etc. An intermingled planting will also combine plants which occupy a number of niches: upright, sprawly, clump form, etc. The more that space is occupied, the less room there will be for invasive weedy species.

This latter point is part of the wider point that James Hitchmough makes about using seeded mixtures, that plants choose their own places, and establish a series of natural relationships with each other. The result will almost inevitably be more resilient to weed invasion. Designed plantings often suffer from damage (idiot rides motorbike over park planting, visitor-thief pulls plant out and stuffs into handbag etc) – intermingled plantings offer a variety of species to respond to this damage, and so are surely more resilient. We need however to back this up experimentally. Work at the University of Sheffield may contribute to this, but is not yet in the public sphere.

Monocultures in nature and in the garden

More on that word ‘monoculture’ later. Up until now, commercial landscapes and larger garden planting has relied heavily on single-species (i.e. monocultural) blocks to create visual effects in planting design. Thomas argues that these are quite common in nature. I disagree. Often what appears to be monocultures are not. Anyway, this is kind of irrelevant as we are arguing that monocultures are often dull. We are arguing that intermingling creates far more complex, and visually rich plantings.

Thomas mentions longleaf pine, the classic tree of the American South. From the air it looks like a monoculture, and it used to cover vast areas on an epic scale, but like so much in the US, it was felled with terrifying rapidity. I have an odd feeling that our kitchen table, made of recycled timber, is longleaf. Look underneath (the tree canopy, not my kitchen table) and you often have a fantastically biodiverse ground flora, which is one reason why ecologists get so excited about longleaf.

Look at bracken on a Welsh hillside, or mahonia in an Oregon forest, and you will see nowt but the same plant, but look beneath and you will find other species, even if they are ‘just’ mosses and lichens.

I actually think that the occasional block planting creates interest, provides a contrast with intermingling, and, since naturalistic intermingling can sometimes have a bad hair day, helps onlookers to read plantings as intentional. Big blocks of grasses are a personal favourite, so are clipped geometrical foliage shrubs – classic box and yew. Except that we are so unoriginal in our use of the latter. Piet (when he used to use this – he doesn’t much now) or other Dutch modernists like Nico Kloppenburg, create far more interesting effects than those designers who are incapable take this use of clipping beyond classical cliches. Tom Stuart-Smith does also some nice, but rather conservative and ‘safe’ clipped punctuation.

So, for me, there is very definitely a role for the block.

‘Monocultural’ by the way has become a bit of a boo word, largely because of the current fashion in food politics, which is to decry all that is modern and science-led in farming. The word is often uttered between mouthfuls of hand-crafted organic locally-produced sourdough bread along with other denunciations of modern agriculture. I would point out that it is all a matter of scale. Go down to your local organic farm and everything will be in monocultures there too, but just on a smaller scale. So let’s be a little more sensible in our use of the word.

Possible pitfalls

Thomas raises some very good points about how bad examples of intermingling could create an image problem for the concept as a whole. Too right. So far, the most highly developed intermingled plantings have been those developed by German and Swiss researchers – the so-called Mixed Planting. See my blog on the subject here: http://noels-garden.blogspot.co.uk/2013/09/its-all-in-mix-resources-for.html

The Germans are famous at getting the technicalities right and producing things which work. The mixed plantings are designed to be relatively stable for at least ten years. I can well imagine a situation in which nurseries start to put together plant mixes which are not properly evaluated or tested and which look a mess after a few years, or where one component spreads or seeds over everything else. Mixes of plants need to be designed by people with plant knowledge, the designers need to defer to the horticulturalists and ecologists.

Maintenance is a possible weak point. However well designed a mix is, there is the possibility that one member runs riot, the Nepeta ‘Veddw Giant’ swamps and eliminates Lobelia ‘Rainer’s Red’. A mix of interacting individuals sets up a situation where competition between species will occur. Even in a really well designed mix this will happen, particularly on fertile soils where competition for resources often results in a ‘winner takes all’ situation.

Managing competition requires plant knowledge and experience, and is not appropriate for the mindless exact-specification-type management required by some clients. It is has been a commonplace of naturalistic planting design for many years that this type of planting may require less management than conventional but that this needs to be more skilled. Given how few skilled horticulture professionals there in UK, and USA, this does rather cast doubt on how viable long-term mixed plantings are. Clients need to be committed to making plantings work by resourcing appropriately.

Having said that, a big thrust of the research associated with mixed plantings in Germany has been the work on mowing, and at Sheffield – mowing and burning. James Hitchmough at Sheffield has been working on extensive maintenance techniques in parallel to working on perennial seed mixtures for some time. These may offer us the best option for public space. For private spaces, garden owners can afford to be a lot more experimental.

Intermingling and mixed planting have liberated us from a straightjacket of thinking. But we have a lot to learn. We have only just started.

Noel Kingsbury

Planting, a New perspective by Noel Kingsbury and Piet Oudolf

(most of the photographs in this piece are from the book)

Noel’s Blog

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