This is a condensed version of a presentation given to the Society of Garden Designers, London, November 2016

Time to widen the boundaries

“Working with shrubs offers solidity, permanence and a three-dimensional quality”

The ‘new naturalism’ in planting design over the past few decades has focused almost exclusively on herbaceous plants and perennials to create beautiful evocations of nature, taking ‘natural’ plant communities and vegetation types, and using them as the inspiration for creating enhanced versions for gardens and designed landscapes. It’s hardly surprising that designers have focused mainly on diverse and colourful grassland types such as prairies, meadows and steppe as their starting point.  However, all the principles of naturalism can be applied to the use of shrubs and other woody plants. Working with shrubs offers solidity, permanence and a three-dimensional quality that perennials just do not offer, along with heightened seasonal visual effects.  But perhaps most importantly, they bring human-level scale and experience – in contrast to the below waist-height, ground-level experience of perennials for much of the year, and the above-head presence of trees.

Below: Low-growing grey-leaved Azaleas forming a framework around mini-glades full of grassland diversity.  Yunnan, China.  Photo: Nigel Dunnett

Why did shrubs fall from favour?

It’s not surprising that shrubs haven’t featured significantly in recent naturalistic planting design theory and practice.  Indeed, the widespread expansion of the new perennial movement in the 1980s from its earlier roots in Germany was to a significant extent a reaction against the dull, stodgy, and unambitious use of ground-covers and shrub-mass plantings in public landscapes, and the tyranny of the ‘shrubbery’ in private ones.  Perennials offered bright colours, seasonal highlights, and the possibility of quick results.  They promoted possibilities for highly creative and artistic approaches, rooted in ecological concepts, and, above all, they opened the way for a more relaxed and natural form of planting.

Below: Shrubs divide and create space at the human level, unlike the overhead of the trees, or the underfoot of the grassland. Photo: Nigel Dunnett

Adapting the principles of the new perennial movement, and applying them to shrubs

Of course shrubs are routinely used in naturalistic perennial schemes, but generally this is as widely spaced or scattered tall multi-stems with open bases and high transparency, to enable co-existence with the perennials.  But we can go a lot further than this, and apply the key principles of the new perennial movement much more widely to include woody plants.  These principles include:

  • Taking inspiration and knowledge from inspiring ‘reference’ landscapes and plant communities
  • Developing an ‘ecological aesthetic’ of horizontal and vertical patterns of plant distribution
  • Understanding the dynamics and competitive interactions in natural plant communities
  • Choosing plantings for their appropriate garden or landscape habitats

There’s no reason why these can’t equally be applied to shrub-dominated plant communities.

Below: a single shrub gives structure in an expanse of dry grassland near Vienna, Austria, with Euphorbia cyparissias

Which Shrub Plant Communities?

In that context, the big question then, is “What are the ‘natural’ reference landscapes and plant communities that can form the basis of a whole new chapter in the development of naturalistic planting?”

In fact, there’s a huge range of shrub-dominated vegetation types, many of which are very familiar: the Mediterranean Maquis, the Chaparral of California, the South African Fynbos, and different type of Heathland.  Some of these types might be called ‘closed shrub’, in that they have a dense foliage cover and form dense thickets, while others are more ‘open’, where the shrub component is more scattered or clumped.  It’s these more open types that, to me, hold out the greatest creative potential.  That’s because, although the vegetation might be dominated by shrubs, they will be part of a mosaic which also includes grasses, herbs, bulbs and small trees.  And when you put it like that, it starts to become a really attractive proposition.

It’s really unfortunate though, that the common names for this type of plant community are often really off-putting and unglamorous: scrub, scrubland, brush!  Perhaps that’s linked to their unproductive nature for grazing or agriculture, but it’s not a good starting point!

Below: dense scrubland on steep slopes in the mountains of Yunnan, China.  Closed, impenetrable scrub is perhaps the least useful model for naturalistic planting design, unless the desire is to fill large areas of inaccessible space.  Photo: Nigel Dunnett

Scrub

This is one of the most unglamorous names of all!  And yet scrub is such an exciting starting point as a model for naturalistic planting.  It’s a bit of a hybrid: a mix of small trees, shrubs, and grassland.  For example, scrub on limestone or chalk is dominated by a vibrant mix of trees and shrubs, mostly in the Rosaceae.  Wild roses themselves of course.  But Prunus (Cherries), Sorbus (Rowans and Whitebeams), Crataegus (Hawthorns), Malus (Crab Apples) too, along with Sambucus (Elders), Ligustrum (Privets), Viburnums, Rubus (Berries) and many others, with vines such as Clematis.  And all this richness is then mixed with patches of diverse and sparkling calcareous grassland.

Below: a) open scrub with flowering Primula sikkimensis in a loose matrix of shrubs with differing colours, forms, heights and textures, in Yunnan, China.  Photo: Nigel Dunnett

b) typical calcareous scrub with wild roses.  Photo Nigel Dunnett

Photo above: Many scrub landscapes are heavily grazed and the often the only shrubs that can survive are armoured with thorns.  The prickly expanse of the shrubs can provide a sheltered environment for perennials to get to flowering size, as here where Valerian officinalis is flowering in the protected space under a Hawthorn.  The shrubs therefore create a nucleus or node of diversity. Photo: Nigel Dunnett

This scrubby landscape has been an inspiration to me – the way the solid Euphorbias and Ligularias are arranged amongst Roses, Berberis and Potentillas is very satisfying.  It was this assemblage that inspired some of the plantings at Beech Gardens, The Barbican (see below)

Above: Dramatic scrub with Euphorbia jolkinii in flower amongst grey-leaved Berberis ternolaika, Rosa sericea, and Potentilla fruticosa, with the striking foliage of Ligularia macrophylla. Near Shangri-La, China.  Photo Nigel Dunnett

Below: Ligularias coming into flower, with shrubby Artemisias and blue Cynoglossum, in scrub near Shangri-La, China.  This mix of an open framework of shrubs creating structural space for dynamic perennials, is an exciting model for planting design.  Photo Nigel Dunnett

Above and Below: Calcareous grassland/steppe with pink Dictamnus albus, with shrubs and small trees in scrub, in Slovakia.  Photos Nigel Dunnett

There is so much potential in using the wild or species roses amongst meadowy perennials, much as many of them might grow in the wild.

Photos below: a beautiful species rose, seen in China (unidentified); Rosa sericea in a wet meadow setting in Yunnan; detail of the translucent thorns of Rosa sericea in the wild.  All photos: Nigel Dunnett

My interest in the interactions between shrubs and grassland in naturalistic systems was first sparked partly by seeing the image below in an edition of the RHS ‘The Garden’ magazine in 1996.  The idea of scrubby invaders into prairie was something very exciting to me, especially as they could be managed through coppicing or cutting back the whole area.  The massing of scrub elements in a prairie gave structure and a more intimate, human-scale of looking at these landscapes, that without this three-dimensional structure would otherwise be overwhelming expanse, and the intensity of the fall colour of the Rhus leaves was unrivalled in that of the perennials.

Above: Rhus typhina growing in a roadside location in the mountains of North Carolina.  Photo Nigel Dunnett

The photo below of a shrubby forest landscape in eastern Canada, scanned from ‘Plants in Garden History’ by Penelope Hobhouse, gives an indication of the dramatic potential of working with shrubs in a naturalistic way.

Some of my earliest experiments in naturalistic planting were modelled on these ideas.  The photos below show some experimental plots from RHS Harlow Carr gardens where I used Rhus typhina and Rhus typhina laciniata as a framework for a diverse matrix of perennials that gave a long-term succession of flowering, culminating with Rudbeckia fulgida deamii and Solidagos in the autumn.  The benefit of using clonal, fast-rejuvenating shrubs such as Rhus is that they can be cut back to ground level or coppiced, and they will generate in a manner similar to herbaceous perennials.  But coppicing is a whole story to itself, for another time.

Experimental plots at RHS Harlow Carr in the early 2000s.    Photos Nigel Dunnett

Using shrubs with perennials: The Barbican

I used some of these ideas in the planning of Beech Gardens at The Barbican, London.  Groupings of multi-stem Amelanchiers and Prunus, with some Sambucus and Euonymus, created a more permanent structural framework within which the predominantly perennial plantings.  The photos below give a sense of how this contributes to the year-round dynamics of the plantings

These are just a few quick thoughts on some of the natural shrub-based plant communities that we can start to bring in from the cold.  There are so many more.  Definitely time to scrub up!

Below: these scrubby patches of Junipers and Potentillas create a permanent and substantive framework for the grassland that interweaves between them.  Photos Nigel Dunnett