Planting styles
One of the great advantages of Gertrude Jekyll's drifts was that it made it much easier to hold on to a form of block, but by stretching them out she made it easier to hide plants with a 'past the sell-by date' look.

There is still strong resistance to straight lines among many who favour natural style gardening, yet an ecologist will point out that a bird does not mind if the tree in which it makes a nest is growing in a row of others or an informal cluster, and many designers will wax lyrical about how straight lines can add a sense of order and intention to otherwise wild-looking plantings.

Moving from planting in blocks to blending is a major shift in planting design.

Over time, plantings based largely on perennials will age. There are two main aspects to this: some species will die out, whereas others will spread, some by simply creeping out from their original planting space, others by self-seeding.

...but now with a better understanding of plant ecology gardeners and designers are in a stronger position to work with spontaneity rather than resist it as 'disorder' in the way our gardening ancestors did. A key problem remains though, the tendency to lose species over time and so lose visual diversity [and presumably ecological!!]

Two types of management can be envisaged: a low key passive one and a more active one [renovation] which works with the naturally dynamic nature of planting.

Renovation might be a better word than restoration.

The human and design context
Planting has to please people and people are part of the ecology too. The point has been made by others that in order for natural environments to be valued by humans they have to be liked.

The role of the gardener or designer is clear, and arguably more important that ever: planting which serves a purpose has to look good too.

...some of the most popular, easily propagated and resilient perennials do look bad after flowering. Keeping such plants to no more than an absolute maximum of 30 percent is a good rule.

Formality and mass planting
Novel forms of formality such as asymmetric clipped woody plants or blocks of grasses are nowadays more likely to be seen as appropriate in large and grander contexts than their traditional forbears.

One of the great uses of any kind of mass planting is that it can contrast so effectively with highly complex and diverse plantings of perennials, giving architecture and backbone to what would otherwise be too visually soft-textured for some environments.

Making wild-looking plantings
The more recent tradition is how to create the sensation of nature, often in urban or suburban areas.

When people say they want some nature, what they usually mean is a particular vision of nature, one that looks nice, fitting in to a distinctly human-centred idea of what nature is or should look like. Nature-lite in other words.

The task for the gardener or designer is to create an enhanced nature, one that supports an acceptable level of biodiversity and looks just a little bit wild.

Developing an identity
Signature plantings are about making something that is site-specific and gives the garden or landscape a distinct personality which helps to make it memorable (LINK TO RUSSEL PAGE AND PLACE OF GARDEN)

Complexity and scale
As the scale gets reduced, so the importance of limited key spaces within sight becomes greater...At this level, layering becomes of greater importance that at larger scales.

Climate change and diversity
Many of the plants relied upon [in the nursery trade] are descended from one single introduction, and may be quite unrepresentative of the species as a whole.

Re cultivars: clones or extensively grown varieties with narrow genepools are susceptible to the spread of disease. In addition, some cultivars are sterile and even if they do produce viable seed, the gene pool of a population of cultivars will be restricted.

Little research has been carried out, but it is likely that the continual use of mowing machinery for keeping turf grass short involves greater resource consumption

There is one tendency which still needs questioning - the size of plants in new projects. It is accepted that small plants usually establish better and more quickly than large ones.

Every perennial in a two litre pot as opposed to a half litre weighs four times as much and takes up about four times the space in a van.

The case for using small plants is easily made for perennials, which tend to grow quickly, but is less easily made for woody plants. What can clinch the argument is pointing out the small woody plants often catch up with larger ones in a few years, such is their superior ability to adapt. It is also worth remembering that large (and therefore expensive) plants are high risk - they are more prone to drying out, and so large initial investments are more likely to be lost than small ones. Small plants are not only more sustainable, but a safer investment too!

Native and exotics
There does seem to be a consensus that using only native species is entirely appropriate in certain environments - chiefly rural ones or where the conservation of local and indigenous biodiversity is a priority.

This is perhaps the most crucial point here - that prior to the current wave of interest in native plants, the nursery industry produced and sold what was beginning to look like a global flora of easy to use, easy to propagate plants. In the case of plants used by the landscape industry, they may have been different from one climate to another, but the effect was the same - too often both architecture and planting could be anywhere.

The use of a proportion of locally native plants can do much to add a distinct signature to projects.

Native plants are often a hugely underexploited design resource...Increasingly, gardeners, nurseries and designers are realising this, and undertaking this 'close to home' plant hunting. Even in Britain, withs its restricted flora and long garden history, we are still learning to exploit the ornamental potential of our wildflowers - look at Stachys officinalis, almost unknown as an ornamental twenty years ago.

Grouping plants
We should point out here that meadows and prairies are maintained extensively - everything has to treated as one, and there is no possibility of maintaining individual plants - whereas in a conventional garden or landscape planting, individuals are often treated differently.

With the rise in naturalistic planting, two developments have arisen which aim at a more thorough detailing of plant groupings. One is a randomisation approach, which is derived from the almost-random effect of sowing a wildflower meadow from seed.  The other is the work of Hansen and Stahl, who from the 1960s onwards developed a highly structured approach which aimed at a stylised representation of natural plant communities.

...both Oudolf and Hansen/Stahl recommend that plantings comprise about 70 percent structural plants (those which maintain distinct visual structure for most of the growing season) and 30 percent filler plants (often rather formless, grown mostly for early season colour).

One simple innovation which can make a great impact on many different scales is the shaping of hedges. Instead of cutting straight, the individual plants in them can be given curves, so that each ones stands out as an individual.

It is useful to think about a hierarchy of plants terms of impact: primary, matrix and scatter.

Just as in all but the smallest domestic gardens repetition provides a sense of rhythm and unity, in large scale plantings which use more or less equal-sized groups there is also a need for repetition.

Drifts can create an illusion of intermingling, and they have certain advantages for ongoing management above mixed plantings.

...whether in a private garden or a larger public space, the repetition of a few distinct long-season plants creates a feeling that 'this is one place, with one design and one vision'.

Matrix planting
...good matrix plants are visually quiet, with soft colours and without striking form. They also need to be effective in physically filling space - part of their function is to be ground cover, so they need to mesh together well.

Grasses are the obvious plants to use for matrix planting, especially cespitose species, or the denser and slower growing clump-forming species.

The potential of Carex and other similar plants (Luzula, Ophiopogon, Liriope) to act as matrix plants is enormous.

Varieties of Molina caerulea also offer the hope of greater stability, although the tight clumps of many cultivars of this genus leave a lot of bare soil between them and so are best in combination with low spreading or sprawling perennials such as varieties of Calamintha.

Other possibilities for matrix planting are those lower growing species which run, generally these are suited to shaded or partially shaded habitats where grass growth is weak e.g. Phlox stolonifera

Finally, there is the potential of certain late flowering perennials as minor components in a matrix e.g. Limonium platyphyllum

In a private garden or small space, this idea of the matrix as something which is uniform is probably important to keep to, as part of the concept of the matrix is its simplicity.

In more extensive landscape plantings, greater interest and greater naturalistic effect might be achieved by not having an identical matrix spread over large areas.

Combining matrix and block planting
The discipline needed to restrict the numbers of varieties necessary for matrix mixes to work is perhaps too tight for many locations, where a wide variety of plants are needed to engage the onlooker. There is also the fact that matrix planting, being a kind of man planting, is particularly dependent for its success on the plants used flourishing and growing on the site chosen - hence fewer risks and innovation. Combining the mass effect of matrix planting with blocks enables a compromise, with plants less well understood by the gardener or designer being used in small groups.

Scatter plants
Species which appear more or less at random through a planting can be termed scatter plants.

This technique is useful for a variety of plant forms which enhance a planting through a seasonal splash of colour of long period of distinct structure - the point is that they must be distinctively different to the rest of the planting.

Layering plants - reading nature and writing design
For planning purposes two or three layers are all that is needed, although these can potentially include several plant categories.

On parts of the High Line, there is a clear distinction between shrubs and a ground layer of grasses/sedges and perennials - here there are two layers. In other areas the planting is divided into layers which are conceptual rather than physical - a matrix layer and a layer of perennials in clumps or groups.

Combining plants
Given that colour is basically about flowers, and since flowers are relatively short-lived, it makes sense for structure to be seen as the fundamental aspect of ornamental plants.

We, Piet in particular, wish to downplay the importance of paying too much attention to colour.

Naturalistic planting promotes the use of wild species or cultivars very similar to the wild species, where the size of the flower relative to the rest of the plant is not so large.

Plantings work best if these two are used in a ratio of approximately seven structure plants to every three fillers:
- Structure plants: clear visual interest, other than being reliant on flower or foliage colour, until autumn at least
- Filler plants: only used for flower or foliage colour; structural interest early in season, but becoming formless or even untidy after mid-summer

With temperate Eurasian and North American species it is difficult to have 'too much' structure, as the palette of plant shape tends toward a great similarity of form: shrubs tend to have a rather amorphous shape and a very large number of both woody plants and perennials have small leaves, creating a diffuse and unemphatic appearance.

Tropical and near-tropical climates offer a whole order of magnitude more options in plant form and foliage form and size.

Other than grasses, the most important structural element is the single vertically thrusting stem. The repetition of identical strong verticals can be a very powerful device for stamping unity on a planting, especially since many of these have good temporal continuity with strong seedbeds following on from their flowers.

Plants for all seasons
The international trade in plants has resulted in spring in the garden being a remarkably similar event around the world.

Tatty daffodil leaves are easily hidden behind vigorously growing perennial clumps in late spring and early summer, but careful planning is needed. Another way of minimising this problem is not to group the bulb as is often done, but to scatter them so that their foliage is then distributed rather than being a prominent clump.

The ease with which many bulbs can be added and grown among other plants and the fact that they are dying back by the time that they perennials are beginning to perform make it possible to think about the spring planting as being quite different in design conception to the summer planting.

Summer dormant perennials
A great many woodland or woodland-edge perennials hug the ground, flowering early and tending to die back early...Species such as these can be grown in close proximity to later perennials, often flowering before many have even woken up.

Anemone nemorosa is known to be able to occupy clumps of the infamously invasive Japanese knotweed...Autumn flowering Colchicum species can also grow among the knotweed.

Late summer and autumn - the second spring
It is customary in Mediterranean climates to talk about the cooler and often wetter days of early autumn as being a second spring: annual seedlings germinate, some bulbs flower, perennials emerge from dormancy with fresh leaves and sometimes flowers.

This is the time when planting design has to cope with maximum biomass. In addition, many of the species which are at their best now are from environments where height is everything, such as prairie and tall-herb flora: plants will have spent all summer growing as tall as they can in a competitive race for the skies. Fertile and moist soils will support the kind of vegetation, whereas less fertile or dry ones will be suitable for much shorter, and in some ways more manageable planting. A mass of tall plants may be attractive from afar but not necessarily close to, as many of the lower stems will be bare or covered in dead leaves, Traditional planting of late flowering perennials was built on the dogma of 'tallest at the back and shortest at the front', which resulted in an even slope towards the viewer, but at least this was a sensible strategy for dealing with tall and leggy perennials. More contemporary planting has opened this out, but still needs to articulate plant heights. Contrast and differentiation between taller and lower plants has to be achieved or it becomes a mass of more or less all head-high plants. Shorter grasses have a valuable role, and there is still a space for lower-level filler plants, some of which are either still in active flower or repeat flowering, as with many of the geraniums. Plants of medium height with good structure are at a premium now, and it mostly grasses which fit the niche.

Blocks
Blocks of very tall plants surrounded by shorter ones or used in ways which define them and separate them from other parts of the planting can work, and are particularly effective for species which do not have good structure.

Emergents
Plants which are notably higher and therefore seen separately to their fellows are extremely useful. An effective emergent is at least a third taller than surrounding plants.

Transparency
Plants with masses of tiny flowers/seedheads on fine widely flung stems can be incredibly valuable. It is possible to see through them to other plants or whatever is behind.

Late autumn and winter seedbeds and dead foliage need good light to look their best.

Putting some plants in pots around the garden before planting them, to make sure the effect works, is a good idea. The planting situation also needs to be visible from a path, a viewpoint or the house in order to be appreciated.

Effective combinations
pp 162-173

Long Term Plant Performance
In trying to understand how plants survive and coexist in the wild, ecologists have developed a number of different models. One of the most successful is the CSR model, which stands for Competitor, Stress-Tolerator and Ruderal.

For the practical designer and gardener there are four key indicators of long-term performance. Plant species tend to combine these in different ways:
- Inherent longevity
- Ability to spread
- Persistence
- Ability to seed

The 'true perennials' category contains plants which have a variety of growth habits; the most important distinction is between 'clonal' perennials (which spread) and 'non-clonal' (which do not).

Examine the base of the plant - if there are clearly shoots with their own independent root system, then the plant is clonal, so it is going to spread and be a long-term survivor. A good example is any one of the pink-flowered Geranium endressii or G. x oxonianum cultivars.

One paradox is that some very long-lived perennials spend most of their first years producing roots and making very few leaves; these roots will ensure long-term resilience and survival, but until they are in place, the weak top growth is vulnerable to slugs, drought or being overshadowed by a faster growing plant.

Ability to spread
Vegetative spread has been described by ecologists as being either phalanx - where a clump expands in all directions at once - or guerrilla, where odd shoots appear at some distance from the parent plant, and are only followed by clump formation if there is little competition.

Perennials with an ability to spread are classic competitor-strategy plants, fighting to increase the amount of space they control, to spread themselves at the expense of others.

Weak rapid spreaders with low persistence have value for infilling between larger plants; strong ones which persist or out-compete neighbours have most value in low-maintenance environments where strong weed suppression and minimal intervention are most important. Guerrilla spreaders can create some attractive spontaneous effects in a similar manner to self-seeding plants if only a few stems pop up here and there.

Persistence
The value of slowly spreading and persistent plants to the gardener and designer is clear. They can form a reliable part of long-term plantings, often without the problems of needing to control them after a few years, which can happen with those which are persistent but spread more strongly.

Ability to seed
The level to which species self-seed is very unpredictable; whereas vegetative spread is more or less predictable, seeding is not - it is dependent on a great many factors, such as soil type, temperature and moisture levels in spring.

As a very general rule, the shorter the expected lifespan of a plant, the more seedlings it will produce.

Biennials and short-lived perennials do not spread vegetatively, so at least the ability of individual plants to physically out-compete other members of a planting is limited.

Piet says. 'I have a rule in planting design using biennials and vigorous self-seeders. I hardly use them and if I use it it as an extra in gardens that are established so that there is limited space and enough competition to limit their numbers.

Mingling currents in contemporary planting design
Whereas design in the past focused on precise plant placement and juxtaposition, these techniques all aim to create the apparent spontaneity of natural vegetation. They do this not by setting out a plan but by planting a mixture - or, to put it another way, they are about creating a vegetation.

Dan Pearson: Modular Planting - Tokachi Millenium Forest

Roy Diblik: Planting Grids

Germany: Mixed Planting
Mixes are developed for different habitats, but are also based on visual themes, particularly colour.

look at index for rapidly spreading plants


The Sheffield School
The use of native plants in Sheffield School plantings is limited to projects where their use is particularly appropriate - a reflection of the very reduced British flora, and the presence in the flora of a number of aggressive species (mostly coarse pasture grasses) which can, if used indiscriminately reduce the potential for supporting biodiversity.

Planting aims at matching the fertility of the site with appropriate species. For example, perennial planting on fertile soils are very prone to invasion by weeds, especially since most perennials drop their leaves in winter, and aggressive grasses and other with winter-green foliage are able to take advantage during this period of dormancy. The use of tallgrass prairie plants from an ecosystem with moist, high fertility soils can minimise this however, as at a high density their leafy shoots and root systems so monopolize light and soil that any unwanted species which establish are often held in check. Conversely, low fertility sites are appropriate for species derived from plant communities which are used to extracting the most out of limited resources, such as European dry meadows.

Hitchmough says that the planting 'should be designed so that a management operations is applied to all the plants across the whole site and which disadvantages the plants you don't want and advantages those that you do...This is an alien concept to most designers'.

The new planting
High plant density is fundamentally a major break with the past. Jame's [Hitchmough] point is that a density approaching that found in natural plant communities is far more resilient than traditional ones with spaces between the plants. Maintenance will also be reduced. Greater resilience results from:
- reduced space for weeds to infiltrate, and greater competition for them if they do establish
- reduced space for seedlings of the aggressively seeding components
- more competition to limit the aggressively spreading components
- reduced plant size owing to greater competition, resulting in a reduction in top-heavy growth and therefore less need for staking
- support for species with weak stems

The Sheffield School stress ecological process and dynamism - the idea that planting will change over time and that the role of the gardener or manager is to direct these processes in a way which preserves or enhances their visual qualities and other desired features, such as species diversity.

Any planting which approaches the density of a natural plant community rather than a traditional garden is going to need a management style which emphasises operations to the whole rather than to individual plants and to the idea of editing an ongoing process - extensive rather than intensive management.

Enhanced nature
[Stephen] Budiansky argues that for too long we have confused ecology as a science with ecology as a political philosophy.

Science, [Stephen Budiansky] suggests, now tells us that natural communities are composed of whatever species happened to arrive and establish themselves, and that chance and random events have played a large part in this.

As an example, two invasive alien species which many in Britain have learnt to hate, Acer pseudoplatanus and Rhododendron ponticum, may have been native prior to a previous ice age; replay geological history and they might have been natives again.

[Emma] Marris takes a fundamentally optimistic, and at times quite joyful, look at how the massive human impacts on natural ecosystems result in not necessarily in a loss of nature but in a new nature as alien and native species adjust to each other, developing entirely novel ecosystems in the process.

We are involved in creating an enhance nature. This idea recognises the importance of visual beauty for human users and the fact that artificial ecosystems can support considerable and valuable levels of biodiversity. There should be no contradiction in pragmatically designing plantings which combine native and exotic and which provide value for human and other users.

Plants
Upright Verbascum leichtlinii is one of several species of a large genus in a family (Scrophulariaceae) where a great many are either biennials or short lived perennials.

Astilbe chinensis var tacqueti 'Purpulanze', a robust and long-lived perennial eminently suitable for drainage swales and other sustainable drainage plantings.

An annual composition of Hordeum jubatum (wild barley) and dahlias, a playful evocation of spontaneous plant communities of waste ground.

Molinia caerulea 'Dauerstrahl' is a native (UK) plant of acid soils across Northern Europe.

Deschampsia cespitosa can die prematurely on fertile soils, and some cultivars are susceptible to fungal diseases and can suffer extensive dieback.

A mix of early summer flowering Salvia cultivars are used to dramatic effect in Chicago's Lurie Garden: S x sylvestris 'May Night', 'Blue Hill, 'Rugen' and S. nemorosa 'Wesuwe'.

Chasmanthium latifolium, a relatively shade-tolerant North American species.

Frequent cutting back stimulates suckering. This technique can be applied to some familiar plants such as Cotinus coggygria and Rhus typhina.

What is important to stress here is that the two Molinia cultivars, 'Heidebraut' and 'Edith Dudszus', are both planted in monocultural blocks, but in the form of complex drifts. If the two varieties had simply been mixed together the effect would have been a blur, as they are too similar to be easily distinguished.

Combining Anemone levelled and Ceratostigma.

...the tall, self-seeding umbellifer Peucedanum verticillare, was intended to provide an element of the unpredictable as well as an imposing winter sight.

A classic autumn or early winter trick involves putting together a hard, dark, defined shape such as the globes of Echinops bannaticus with soft, pale, wispy grasses e.g. Deschampsia cespitosa

Mertensia virginica (and other related species) is a good example of a perennial which is able to fill spaces between other plants [because it's summer dormant], even flourishing in the centre of dense clumps of grasses.

Here, blue Salvia azures and yellow Heterotheca camporum var. glandulissimum make an impact.

Peucedanum verticillate has a habit very typical of umbellifers. It is monocarpic, after two or three years growth. However, it self-seeds well in most gardens.

Eupatorium maculatum 'Snowball' with Persicaria amplexicaulis at Hummelo. Eupatorium only forms clumps slowly, while Persicaria does so at a somewhat faster rate.