The Garden of Cosmic Speculation is a pioneering, late 20^th century design by the internationally-renowned landscape / land art designer and theorist of postmodernism, Charles Jencks (1936–2019) and his wife Maggie Keswick.

Laid out on a grand scale for artistic, demonstrative and contemplative effect, and inspired by recent scientific discoveries and theories, the garden uses landforms, buildings, sculpture, water, typography and planting to embody notions of space and time, energy and nature, and the relationships between things at every scale, from the sub-atomic to the universal.

Type of Site

A large artist's garden and artwork inspired by contemporary scientific discoveries and theories about the underlying nature of the universe.

Main Phases of Landscape Development

19^th century; 1988–2012

Artistic Interest

Level of interest

Outstanding

• The Garden of Cosmic Speculation is a 20^th century designed landscape of outstanding artistic importance by the internationally renowned landscape designer and theorist of postmodernism Charles Jencks, in collaboration with members of his close family.

• Developed gradually in a receptive manner, involving artistic and practical concerns simultaneously, the layout and installations closely reflect Jencks' ideas and intentions, with the garden designed to complement and contrast with the earlier development of the landscape at Portrack.

• Media reports and reviews demonstrate an appreciation for both the scientific and artistic achievement of the garden's exploration and description of contemporary ideas and theories concerning the nature of the universe.

Historical

Level of interest

Outstanding

• The planning and construction of The Garden of Cosmic Speculation is well documented. The Jencks estate holds a large collection of images from the 1990s through to the early 2000s. Design drawings are reproduced in Charles Jencks' books 'The Garden of Cosmic Speculation' (2003) and 'The Universe in the Landscape' (2011), while further archival material is curated by The Jencks Foundation (www.jencksfoundation.co.uk).

• The Garden of Cosmic Speculation contains important formative examples of the turfed landforms with which Jencks has become closely associated, such as those at Jupiter Artland and the Scottish National Gallery of Modern Art in Edinburgh.

• It has historic interest as Jenck's family home and personal garden where he nurtured and developed ideas, with input from immediate family members and Head Gardener, Alistair Clark, that he then drew from for future projects elsewhere. 

Horticultural

Level of interest

Some

• Some interest derives from the variety of often unusual planting, which helps frame, accentuate, contrast with, and add meaning to the various design elements throughout the garden.

• There are no scientific collections or recorded champion trees within the garden. 

Architectural

Level of interest

High

• Portrack House (LB10531) and the octagonal summer house (LB10532) are recognised for their special architectural and historic interest.

• Other architectural features include the Steading (Lower Portrack), the Universe Cascade and its pavilion, the red zig-zag rail bridge, and the undulating walls and gates of the kitchen garden. These also contribute to the interest under this heading.

Archaeological

Level of interest

Some

• Upstanding remains of Portrack Castle (circa 1600) are located within the boundary of the designed landscape (Place Record UID 65899).

• As with many gardens and designed landscapes, there is some potential for future investigation to reveal further information about the site's past.

Scenic

Level of interest

Some

• Due to its physical extent, scale and character, the Garden of Cosmic Speculation contributes some visual interest to the local landscape. Although partially screened by belts of trees, its landforms can be glimpsed from passing trains on the adjacent railway line and seen in more distant views, where the garden's arboreal variety offers contrast to the surrounding fields and agricultural settlement.

Nature Conservation

Level of interest

Some

• The gardens at Portrack House contain several different habitats including ponds, meadows, streams and woodland.  New plants and trees are being introduced to some areas to increase the biodiversity of the site (Information from owner, 2023).

The Garden of Cosmic Speculation is located within the grounds of Portrack House beside the River Nith, approximately six kilometres northwest of Dumfries. The Garden of Cosmic Speculation covers an area of around 12 hectares within the wider 300-hectare Portrack estate.

From within the designed landscape there are views northwards towards the River Nith, which largely defines the northern boundary of the site. The hills on the north side of the valley form a backdrop to some elements of the garden design.

The 1st Edition Ordnance Survey map (surveyed 1855) shows the layout of Portrack at that time, with an informal arrangement of parkland, woodland and lawn predominantly to the west and north of the house, interspersed with individual parkland trees.

The Garden of Cosmic Speculation was developed as an open-ended experimental garden and land-art project, from 1988, by Charles Jencks and his wife, Maggie Keswick, whose parents had owned and lived at Portrack since the 1950s. Their principal collaborator on the project was Alistair Clark (Head Gardener at Portrack Estate, now retired).

It evolved in a deliberately gradual manner, often using practical circumstances as a springboard for the addition of new design ideas and installations, and latterly with the involvement of other immediate family members including daughter Lily and son John Jencks.

Portrack House and its grounds remain a private family home, and work continues at the garden to this day (2025). 

Charles Jencks and site design

Charles Jencks (1936–2019) was an internationally renowned cultural theorist and landscape designer. With his wife Maggie Keswick Jencks (1941-1995) he was also co-founder of the Maggie's Cancer Care Centres.

Resident in Scotland and England for most of his life, American-born Jencks was among the first to chart the rise and question the fall of Postmodernism as a cultural movement or epoch. The evolution of his thinking can be charted through more than 30 books published since 1972, many of which have been reprinted in evolving editions. Maggie Keswick's book, 'The Chinese Garden' (1978) was an early study on the designs of the historic Scholar's Gardens of Eastern China. The Jencks' began to focus on the act of landscape art and garden design during the 1980s to further explore their ideas.

The Garden of Cosmic Speculation was their first landscape project of scale. As the garden gradually evolved, they developed a personal philosophy of garden and landscape design where discoveries about the underlying nature of the universe provided a new iconography for art, and where established notions of science and of gardening could be questioned (Jencks, 2003). Mixing architecture and landforming with sculpture, planting and inscription, Charles Jencks wrote that they were trying to develop a new language of landscape design (Jencks, 2003:17).

In many cases, specific design ideas began as an ad-hoc response to practical issues and circumstances within the garden, where the solution involved the application of additional scientific, artistic, and philosophic meaning. Jencks referred to this problem-solving aspect as 'alibis for formal invention' (Jencks, 2003).

The ideas developed in the Garden of Cosmic Speculation influenced Jencks' later works, in what he referred to as the 'Universe Project' (2003: 235). Other works by Jencks in Scotland include Ueda Landform (2001) at National Galleries Scotland: Modern in Edinburgh; the Cells of Life (2009) at Jupiter Artland, West Lothian; and Double Walk (2011–2012) at Midpark Hospital in Dumfries. Crawick Multiverse (2008-2015), also in Dumfriesshire, was his last major design (GDL00413).

The garden follows a precedent for personal, owner-designed landscape gardening on a grand scale in Britain from the early to mid- 18th century onward, made by individuals with something specific to say with their estates, whether political, philosophical, or artistic. Another example of a contemporary artistic landscape of outstanding significance in Scotland is Iain Hamilton Finlay's Little Sparta (GDL00265) in Midlothian.

Critical acclaim for the garden and its underlying intentions has come from eminent scientists and other commentators. Polish American architect, Daniel Libeskind described the garden as 'an adventurous and personal journey through time and space', while cosmologist and Astronomer Royal, Sir Martin Rees considered that 'a rare insight into nature's patterns' is brought to life in the garden (Jencks, 2003). Some have drawn parallels with innovative garden designers and writers of the past, such as Alexander Pope (Stephen Anderton, The Times, 2003). The garden has also been referred to as one of the most original and important gardens of the 21st century.

Architectural Features

Portrack House (LB10531) is the architectural focal point of the site. Originally an early 19^th century farmhouse, it was enlarged by James Barbour in 1879, with further alterations in the 1950s. It is named after the medieval Portrack Castle (Place Record UID 65899), the fragmentary remains of which are to the north of the house. To the northwest, The Steading (Lower Portrack) is a group of ancillary buildings dating from the mid-19^th century.

Within the gardens, the Summer House / Octagonia (LB10352) is a small octagonal lodge house of 1770, salvaged from Mollance House and reconstructed at Portrack by Maggie's father, Sir John Keswick in 1970. Charles Jencks transformed the interior to function as a library and workspace, with the design concept based entirely around the number eight. The building functions as an eye-catcher, while also referencing an earlier Classical age of garden design. A folly-like building named 'The Nonsense' completed in the 1990s was destroyed by a falling tree in the storms of winter 2024/2025.

Other features, including landforms, architectural works, sculpture, terraces, bridges and fences are described under The Gardens.

Woodland

A compact stand of mixed woodland, known as Crow Wood including the Garden of Taking Leave of Your Senses, is located towards the centre of the site. The former 19^th century tree species in this area, including lime, birch and cedar, have been supplemented with an unusual mix of colourful tree species, including blue cedar, red acer, and amber sweet gum.

A grove of silver birch was planted as part of the Birchbone Garden in 2007.

The site retains the earlier structure of traditional mixed belts and clumps of deciduous and evergreen trees, and some mature individual specimens. These provide backdrops and site lines to the various later artwork installations and landforms. They also partially screen the garden from the road to the south and the railway line to the north. Some trees were lost during storms of winter 2024/2025.

The Gardens

The Garden of Cosmic Speculation consists of several distinct areas or installations (described below), largely constructed between 1988 and 2012.  The Garden is densely packed or coded with ideas, metaphors and narratives, designed to encourage varied responses to and relationships with multiple aspects of nature. The central metaphor of the Garden is that the universe and everything in it is 'a co-ordinated symphony of vibrating waves of energy' (Jencks 2003: 107) where 'order emerges out of chaos, and complexity out of simplicity' (Jencks 2011: 260).

Connections of alignment, proximity and scale are drawn between the newer design elements and the older structure of the garden including the topography, as well as the distant borrowed landscape of the hills to the north.

Progression around the garden is not narratively structured in any traditional sense, and there is no set route around the garden. Principal areas may be connected by mowed or paved pathways, timber decking, or vehicle tracks, depending on practical necessity as well as artistic intention, in keeping with the broader philosophy of the garden.

Linear Paradise Garden / Clare's Walk: This is a long area of planting in informal beds running adjacent to the south approach road, contrasting colourful borders with tall shrubs and trees. It was created in the later 19^th century upon and between mounds of earth moved from 19^th century levelling works to create a lawn for games such as bowls or croquet. This element of the garden was tended by Maggie Keswick's mother during the mid- 20^th century and has been retained largely unaltered.

Snail Mound, Snake Mound and Slug Lakes: The Snail and Snake mounds (begun 1988) are the earliest examples of Jencks' large turfed and stepped landforms, which became a signature motif. They are of exceptional importance within the context of Jencks' later landscape work - his 'Universe Project' (Jencks, 2003: 235).

The twisting, elongated Snake Mound is over 100 metres long and 20 metres high at its tallest point. Its S-curve draws inspiration from the shape of wave-form energy. The spiralling Snail Mound, with its twin-path ascent and descent, alludes to various things including architectural archetypes, the double-helix of genetic DNA, the shape of solar systems and galaxies, Chinese garden traditions, and ideas relating to human progress and pilgrimage (Jencks, 2003). As evidenced by their names, these features may also be interpreted anthropomorphically. The landforms also resonate with the borrowed natural landscape of undulating hills, visible several miles away to the northwest.

The Slug Lakes are two curving swimming ponds, on the site of an earlier area of boggy marshland, bisected by a narrow turf causeway. A curve or tail of land extends out into the main body of water to the east. Two red curving bridges, with forms inspired by fractal geometry, cross narrow streams exiting the lakes to the west. Smaller arched red bridges connect pathways through the verdant low-lying area of the garden to the north of the lakes.

Symmetry Break Terrace and Black Hole Terrace: These features to the west of the house and lawn are set within a long sinuous retaining wall inspired by the shape of soliton wave energy. The wall is constructed of river stones set in diagonal patterns which evoke a piling up of geological strata over time. Due to the slope in the land the wall is not visible from the house and functions in much the same way as an 18^th century 'ha-ha', separating the areas intended for grazing from the more formal designed areas and lawns closer to the house.

The contracting and expanding aluminium chequer-board shapes of the Black Hole Terrace is a primary motif within the context of the garden. It illustrates super gravity pulling one universe to a point of singularity before transforming it on the other side into a 'self-similar but not self-same' universe (Jencks, 2003). The terrace is aligned with a solitary tree on meadowland to the north.

The Symmetry Break Terrace, further along the wall to the north, is an elliptical inset pattern of gravel and turf strips. It conceives the history of the universe as four eras corresponding to the emergence of energy, matter, life, and then consciousness. The symmetry breaks are aligned with the same tree.

The Universe Cascade and Pond: Completed in 1996, the 'Universe Cascade' is a multi-branched, multi-levelled staircase of white concrete, located on the steep incline to the immediate rear of Portrack House. A narrow channel of water running down the branching steps counters a 13-billion-year timeline narrative running up, with important cosmic events or 'jumps' outlining the history of the universe, sculptured into 25 individual platforms using a variety of materials including volcanic rock and river stones. At the bottom of the cascade, the steps disappear into a dark pond representing a point of origin for the universe. Shaped turf-mounds with metal insets and water fountains surrounding the pool are inspired by the shapes of theoretical universes, and the impact of gravitational and other forces upon them.

DNA / Six Senses Garden: The DNA or Six Senses Garden is a rectangular 'kitchen garden' space to the northeast of Portrack House, surrounded by undulating walls and consisting of six rectangular 'cells', divided by box hedging and pathways. Each cell contains a sculpture and planting relating to one of the five human physical senses and the double-helix structure that carries our genetic code. Planting is specific to each sense, with varieties chosen for their scent, taste, feel, appearance, or sound when blown by the wind. The sixth cell relates to the 'sixth sense' of intuition. Shaped metal gates, patterned pathways, benches, and inscribed words and aphorisms are all part of this densely encoded area of the garden.

A large glasshouse to the immediate north has die-cast metal roof ridges that take the form of mathematical equations relating to key scientific laws of nature.

Comet Bridge and associated planting: The Comet Bridge links the central wooded area (Crow Wood) with a raised pasture or meadow to the east. It takes the shape of an elliptical comet or asteroid in flight. The bridge walkway is made of steel I-beams with punched circular holes, and the railings are aluminium fencing. On the woodland side is an oval boulder with colourful tree species planted around it including red maple, yellow-barked ash, silver-leafed white-beam and copper beech. 

Quark Walk: Located on a path beside a water course, on the north-eastern boundary of the garden site, this installation features eight red-painted tree trunks representing the pattern created by the mixing of different types of quark particles. The mesh-like fabric of an undulating fence running through the trunks refers to the interference caused by light wave particles, splaying out as metal fronds over the water course.

The Garden of Scottish Worthies / Garden of Rails / The Bloodline: The Garden of Scottish Worthies (2002–2003) was developed during upgrading works to the active railway line and bridge over the river Nith. The replacement bridge is known as the zig-zag bridge. It stands alongside 'the bridge to nowhere' - a cantilevered reworking of remnants of the 1845 bridge. This infrastructure, designed by Charles Jencks in conjunction with Scott Wilson and Carillion, won the Saltire Award for Engineering Excellence in 2004.

The installation considers the impact of rail travel on social and industrial progress, equating it with the Scottish Enlightenment and the impact Scotland has had on the invention of the modern world. Seventeen turfed mounds line the rail track on the eastern approach to the bridge. These are surmounted by pierced metal signs commemorating seventeen influential 'worthies', mainly from 18^th and 19^th century Scottish history. Running parallel to the turfed mounds, the 'Bloodline' displayed the names of 40 significant people and events, from Agricola in 84AD to the construction of the Scottish Parliament in 1999 through the medium of aluminium banners hanging from a row of poplar trees. In 2025, the poplar trees were removed due to disease/old age.

Metal, stone, and concrete material salvaged from the dismantled bridge and associated rail works were retained and used in the development of this area of the garden, and in the Red Rust Exaptation Garden on the site of a former tennis court.

Fishenge: This work beside the River Nith is located around 450 metres northeast of the zig-zag bridge. Its planform consists of two mirrored triangles of boulders, repurposed from nearby breakwaters or 'croys' that were intended, but failed, to act as resting pools for salmon travelling upstream. The two triangles are bisected by an avenue of boulders aligned on a northwest axis toward the sunrise over the distant hills. There are also angled turf mounds designed to offset the shapes created by the boulders. This installation prefigures Jencks' interest in prehistoric landforms and standing stones, explored further at Crawick Multiverse (GDL00413).

Other installations within the garden include the Garden of Time, the Willow Twist and Birchbone Garden, the Fractal Terrace, the Wave Fence and Gate, the Land and Water Dragon, the Devil's Teeth, the Witches Brooms and Cauldron, and the Red Rust Exaptation Garden.

Trove.scot - Place Record UID: 132046

Maps, plans and archives

Ordnance Survey (surveyed 1856, published 1861) 1st Edition, 6-inches to one mile

Ordnance Survey (surveyed 1938, published 1949) 4th Edition, 6-inches to one mile

Printed sources

Jencks C (1977, revised 1978, 1980, 1984, 1988, 1991) The Language of Post-Modern Architecture. Rizzoli: New York

Jencks C (1973) Modern Movements in Architecture, Penguin Books: London

Jencks C (2003) The Garden of Cosmic Speculation, Frances Lincoln Ltd, London

Jencks C (2011) The Universe in the Landscape – Landforms by Charles Jencks, Frances Lincoln Ltd, London

Wiley D (2011) The Story of Post-Modernism: Five Decades of Ironic, Iconic and Critical Architecture

Online sources

Arts and Gardens Charles Jencks - Arts & Gardens (artsandgardens.org) [accessed 2025]

The Charles Jencks Foundation Jencks Foundation and About – The Cosmic House [accessed 2025]

The Charles Jencks Archive https://jencksfoundation.maxarchiveservices.co.uk/ [accessed 2025]

Charles Jencks, Site (including Curriculum Vitae) Home | mysite (charlesjencks.com) [accessed 2025]

Charles Jencks (2016) The Architecture of the Multiverse: Lecture delivered for Harvard University Graduate School of Design (16/10/2016) Charles Jencks, "The Architecture of the Multiverse” - YouTube [accessed 2025]

The Cosmic House, Historic England List Entry Cosmic House, Non Civil Parish - 1450124 | Historic England [accessed 2025]

The Architectural Review (15/10/2019) Tribute to Charles Jencks Tribute to Charles Jencks - The Architectural Review [accessed 2025]

Eplényi A, Oláh-Christian B (2015) Department of Garden History, Budapest, Department of Garden History and Landscape Techniques (PDF) Postmodern landscape architecture: theoretical, compositional characteristics and design elements with the analysis of 25 projects (researchgate.net) [accessed May 2023]

Hoffman, J. (2011) Q&A: Cosmic Gardener. Nature 473, 283 (https://doi.org/10.1038/473283a) [accessed 2025]

The Telegraph (16/01/2018) The moving story behind Britain's most mind-boggling garden [accessed 2025]

Lily Jencks Studio lilyjencksstudio.com [accessed 2025]