Inventory Garden & Designed Landscape

Glenwhan Gardens and Arboretum, Dunragit, StranraerGDL00411

Status: Designated


Where documents include maps, the use of this data is subject to terms and conditions (


Date Added
Supplementary Information Updated
Local Authority
Dumfries And Galloway
Planning Authority
Dumfries And Galloway
Old Luce
NX 15190 58623
215190, 558623

Glenwhan Gardens and Arboretum is the inspiration of Tessa Knott-Sinclair who, with her late first husband Bill Knott, created the garden from scratch during the late 1970s. Glenwhan is of outstanding artistic interest for how Tessa Knott-Sinclair transformed a wild and seemingly inhospitable site into one of Scotland's most distinctive new gardens of recent times, described as a 'plantswoman's garden for all seasons' (Britain's Finest 2023). The growing body of evidence for appreciation of the site in terms of its design, combination of planting, and creation of vistas over water, also indicates outstanding artistic interest. Furthermore, Glenwhan Gardens and Arboretum are of high horticultural interest for their collections of tender and rare species rhododendron and azaleas, shrubs, and trees, including many rare specimens from China and the southern hemisphere.

Type of Site

A garden and arboretum created out of moorland, with the theme of 'looking down on water'. Planting of the garden is naturalistic and individualistic, and the garden has a wide range of habitats that support a large and diverse collection of rare and tender trees and plants from around the world.

Main Phases of Landscape Development

1979 - present day

Artistic Interest

Level of interest
  • Glenwhan Gardens and Arboretum displays outstanding visual relationships linking features of the garden, particularly the lochans and surrounding planting, with the borrowed landscape/seascape of Luce Bay and the Mull of Galloway on the horizon.
  • There is evidence of growing contemporary appreciation of Glenwhan Gardens and Arboretum as a work of art in terms of aesthetics and experiential qualities. Curtis-Machin praised Tessa Knott-Sinclair's instinctive transformation of 'bleak moorland' into 'magnificent' gardens (2006). In this regard, comparisons may be drawn with Little Sparta which was created by Ian Hamilton Finlay also from "a wild and exposed moorland site" ( Cox commented that Glenwhan is 'a fine achievement on an impressive scale' (2014, 382).  In particular, commentators have highlighted how naturalistic and individualistic planting within the garden has been combined with the concept of 'looking down on water', making use of light and the reflective qualities of water for artistic effect. The addition of the Moorland Walk provides contrast between the land in its former state, and the gardens in their current form.


Level of interest
  • Glenwhan does not represent a particular period in the history of garden or landscape design. While it is a garden created during the 1970s-1990s, it is not representative of prevalent trends in landscape architecture at the time such as postmodernism.
  • Glenwhan Gardens and Arboretum is a plantswoman's garden of the recent past with Tessa Knott-Sinclair describing its design and planting as 'impulsive and instinctive, rather than academic' (Curtis-Machin 2006). 
  • The use of sculpture at Glenwhan also appears to be highly personal and a reflection of Tessa Knott-Sinclair's individualistic approach. Initially popular during the 18th centuries, sculpture in gardens returned to popularity during the 20th century in dedicated sculpture gardens, and in contemporary versions of 18th century landscapes such as Ian Hamilton Finlay's Little Sparta (Eburne and Taylor 2006, 241-4).


Level of interest

Glenwhan Gardens has a notable collection of species rhododendrons, azaleas, hydrangeas and other tender varieties of plants. Cox has described the collection as 'astonishing'. Plant lists are being compiled and maintained, and plants are labelled throughout the garden, in particular denoting species which are endangered (2014, 382).

Glenwhan Gardens and Arboretum has a collection of tender and rare trees from the southern hemisphere and around the world that are recognised for their significance. The Tree Register records (2021) records four champion trees of Britain and Ireland (three varieties of Betula and a Pine), two country champions, and a further 13 county champions (


Level of interest
  • The restored former Grieve's house, an old well, and the re-purposed former reservoir for Dunragit estate (unlisted) add some interest to the character of the garden and designed landscape.
  • The collection of sculptures within Glenwhan Gardens and Arboretum contribute to the character of the gardens, both through their intrinsic interest, their interest as a group, and by their placing at key focal points within the gardens, as unexpected discoveries amidst planting, or in restful spaces.



Level of interest


  • The National Record for the Historic Environment reports an antiquarian find of a handaxe in a drystone dyke within the proposed boundary (Canmore Id 61182). The Ordnance Survey Second Edition map (1894) shows a possible fort to the northwest of the house however the National Record for the Historic Environment indicates that this is a natural feature (Canmore Id 61151).



Level of interest

As viewed from the low coastal ground outside the gardens, to the south, Glenwhan Gardens and Arboretum are secluded, and mostly indistinguishable from the surrounding shelterbelt around Dunragit Estate. As such, the visual impacts of the garden design are limited to views within the garden space and looking outwards.

The National Record for the Historic Environment reports an antiquarian find of a handaxe in a drystone dyke within the proposed boundary (Canmore Id 61182). The Ordnance Survey Second Edition map (1894) shows a possible fort to the northwest of the house however the National Record for the Historic Environment indicates that this is a natural feature (Canmore Id 61151).

Nature Conservation

Level of interest

Although not recognised through any statutory nature conservation designation, Glenwhan Gardens and Arboretum provide a range of different habitats, from wet lands, to moorland gardens and woodland supporting protected species such as red squirrel.

Location and Setting

Glenwhan Gardens and Arboretum occupies an area of south-facing former moorland at around 100m above sea level. The gardens are located 5km from the sea, overlooking Luce Bay and the Mull of Galloway to the south, and with views during good weather extending as far as the Isle of Man.

Glenwhan Gardens and Arboretum is approached from its south-west side, by a minor road that leads off the A75. The main garden and arboretum extends to an area of 5 hectares (12 acres). Beyond this, on the western, northern and eastern sides, there is a further 7 hectares (17 acres) of open grounds consisting of interlinked paths on managed open moorland and known as the Moorland Walk.

The proposed inventory garden and designed landscape includes both the main garden and arboretum, and the Moorland Walk. The proposed designation is bounded by a minor road on the west side, to the north and south, by field boundaries with rough grazing farmland beyond, and to the north-east, by the commercial woodland plantations of Bareagle Wood. 

A central feature of Glenwhan Gardens and Arboretum is two small lochans, fed through a burn that flows in a southerly direction through the middle of the site, drawing an abundant supply of water from a reservoir built probably in the 18th or early 19th century that formerly served the neighbouring Dunragit Estate. Dunragit House (LB16786) and its associated estate buildings, walled garden and woodland designed landscape are located immediately to the southwest of Glenwhan Gardens.  

With a coastal location in Dumfries and Galloway, Glenwhan Gardens and Arboretum benefits from the effects of the Gulf Stream, such as relatively high levels of rainfall (on average 1m per year) and generally mild winters. A shelterbelt of trees, planted around 40 years ago, protects the garden from the prevailing south-westerly and potentially damaging north-westerly winds. The ground is rocky and offers good drainage (Knott 2016). These factors, together with the acidity of the soil (average measured Ph of 5.6) provide a suitable habitat for a wide range of tender trees and shrubs that flourish at Glenwhan but which originate from the southern hemisphere and elsewhere around the world.

Large naturally-occurring outcrops of bedrock within the garden have been named (e.g Thinking Rock; Hideout Rock) by the present owners.

Site History

Glenwhan Gardens and Arboretum is the inspiration and creation of plantswoman Tessa Knott-Sinclair.

The garden began to take shape after Tessa and her first husband Bill Knott bought Glenwhan unseen in 1971 from Sir Charles Cooper before moving there from farming in Herefordshire in 1974 (Knott 2016). Glenwhan, in Gaelic means 'green valley'. Knott (2016) recounted how, at the time of their purchase, the 103 acres of bog, bracken and gorse were described as 'fit for afforestation'.  

The land was initially let for pasture while the Knotts set about creating a family home by renovating a ruined former Grieve's house for Dunragit Estate that had last been lived in during the Second World War by James Kelly, the estate's last resident shepherd, along with wartime evacuees. This building appears on Ordnance Survey 1st Edition 6-inch maps (1843–1882) adjacent to a rectangular enclosure in an area of land called 'Dunragit Moor'. The same maps also depict the reservoir to the north of the gardens which supplied Dunragit Estate.

Tessa Knott-Sinclair had no formal horticultural training, but she had created a garden in Herefordshire and brought her plants with her. Initial forays into the garden involved 'taming' gorse-filled moorland, and growing vegetables on the fertile ground of an old lambing pen. Bill Knott liked trees, particularly hollies (ilex).

The idea of creating a garden at Glenwhan began to take shape in 1979, following visits to Tresco, Isles of Scilly, and to Logan Botanic Gardens, Stranraer (GDL00267). The gardens created by Lady Anne Palmer at Rosemoor, Devon, were also a significant inspiration. Tessa Knott-Sinclair worked largely from a blank canvas and the concept for the garden gradually evolved, growing outwards from the house. 

Acting on advice from Chris Minchin of Game Conservancy, the Knotts planted a shelterbelt enclosing around 12 acres of land, consisting of hawthorn, sorbus, oak, hazel, sycamore, birch and pine. They retained native gorse plants retained as 'nannies' to shelter the young plants and latterly installed fencing to prevent damage by deer. 

The idea of looking down on water arose from discussions with Chris Minchin (Game Conservancy) while sitting on 'Thinking Rock' - a natural rocky outcrop that overlooks the site with Luce Bay in the distance.  As the Knotts began to work the ground, it became clear that a boggy area was being fed with water from a former reservoir above. This offered an abundant water source to realise their vision. They used  a mechanical digger to excavate tonnes of soil, creating a watercourse that tumbles off the hillside before flowing into two small lochans.

The Lily Pond is the smaller of the two lochans. It was created a few years before Glenwhan Pond, the larger and deeper of the two ponds.  At the centre of the Lily Pond is Kelly's Isle, named after James Kelly. 

Planting of the garden began in the early 1980s with 100 hybrid rhododendrons and Knaphill azaleas. Dennis Woodland of Hilliers Nursery and Arboretum in Hampshire advised the Knotts to split the land into smaller named areas, to make walkways, to enrich the soil with farmyard manure and compost, and not to plant too close to the water which would block off the views.

As the shelterbelt grew and a microclimate developed, pathways were cut and species rhododendrons added, as well as many southern hemisphere plants and trees that the Knotts had seen growing in their native habitats while on worldwide tours with the International Dendrology Society. Mostly latterly, Tessa Knott-Sinclair has also introduced sculptures at focal points within the garden.

Glenwhan Gardens first opened to the public in the late 1980s for charity and averages 5,000–6,000 visitors per year (2022), with a tearoom, self-catering lodge and shepherd's hut added to further support work on the garden.

The garden has continued to evolve. By 2006, the Knotts had fenced off a further 17 acres to create a wilderness garden, with meandering walks amidst native moorland, wildflowers, ferns, mosses, and wildlife. In 2010, Tessa and Bill Knott's son Richard Knott, re-designed a vegetable plot at the centre of the garden into a productive formal potager. As the trees in the garden reached maturity, the 'Arboretum' was added to the name and, by 2013, the gardens were promoting a new 'tree trail'.

Glenwhan Gardens and Arboretum continues to exhibit a high degree of integrity and are in good condition. Following Bill Knott's death in 2018, Tessa Knott-Sinclair remains the driving force and inspiration for ongoing development. Expert support comes from her second husband, Ian Knott-Sinclair, formerly of the Royal Botanic Gardens Edinburgh, who collates plant and tree lists and labels the collections. Plans are underway (2023) to create a Chilean garden in the moorland garden by eradicating bracken before planting an area at the north-eastern corner of the Moorland Walk as a Chilean Arboretum, with plants such as Drimys.

Landscape Components

Architectural Features

The garden provides the setting for Glenwhan House (unlisted), a former Grieve's House (a house for a farm manager) for Dunragit estate that was derelict until its renovation by the Knotts during the late 1970s. The remains of an old well which supplied the house with water has been incorporated as a feature into the water garden.  A wooden summer bathing hut and diving board stands on made up ground next to Glenwhan Pond. A second wooden summer house at Tess' Lookout next to Thinking Rock, offers outstanding views over the lochans towards the Mull of Galloway.

Tessa Knott-Sinclair's collection of individual sculptures of bronze and stone are placed at key focal points in the landscape, in secluded spaces to invite contemplation, and/or as unexpected discoveries in the planting. They include the 'Peace Pinnacle', a stack of slate globes by the sculptor Joe Smith, commissioned to mark the turn of the millennium. This occupies a prominent viewpoint at the top of the stream, where garden gives way to the wild. A wild boar, a copy of the famous Porcellino Boar sculpture that stands in the Mercato Nuevo in Florence (Scottish Gardener 2021), looks over the potager towards the water. A huge stone head of 'the Listener' occupies a rocky outcrop on the west of the Lily Pond, known as Hideout Rock. The statue looks out over water, with one hand cupped to an ear, as if listening for far off sounds. A bronze frog jumps between water plants close to the stream. Meanwhile, the stone nude statue of 'a nymph' sits clasping her knees on a plinth, one of several such statues created by Tessa Knott-Sinclair that are located around the Lily Pond. There are also canine statues and headstones in the pet graveyard. 

Drives & Approaches

The garden is approached from the southwest by a drive leading to Glenwhan House.

Paths & Walks

A tree trail links over 160 different species of trees and passes key viewpoints such as Thinking Rock, with views over the lochans below and towards the coast. The trail was created by the Knotts as the Arboretum trees reached maturity.

Within the main garden, a series of interlinked paths 'follow the dips and rises that modulate the garden from the gently pastoral to the savagely rugged' (Knott 2016; 17) enabling visitors to enjoy the different components of the garden. These are covered with protective plant mulch (2022). Board walks allow access over areas of water garden and a path next to the stream leads with steps upwards towards the Peace Pinnacle and the Moorland Walk, where meandering mown grass paths allow visitors to see and compare the garden in its current form, with the native moorland beyond, which is how the garden started out.


Avenues and Vistas

Vistas onto water are a key aspect of Glenwhan Gardens, making use of light and the reflective qualities of water to maximise artistic effect.

Vistas exist within the garden, looking onto the lochans and water garden from the Peace Pinnacle, Tess' Lookout and Thinking Rock, across the lochans from 'the Listener', or across the reservoir on the Moorland Walk.

Furthermore, when viewed from Tess' Lookout and Thinking Rock, these water features fuse into the borrowed coastal seascape of Luce Bay and the Mull of Galloway in the background, and on clear days, even further away towards the Isle of Man.

Water Features

Water is a major feature of Glenwhan Gardens.

At the highest point of the garden is a 18th/19th century reservoir that formerly supplied water to Dunragit House and estate and, which now provides an abundant supply of water to Glenwhan.

This feeds a stream that descends in steps towards a Water Garden before flowing into two lochans, that provide a home for brown trout, carp, newts, and toads. The Lily Pond is separated on the east side from Glenwhan Lochan by a causeway and 'Willow Bridge'. To the east of this, there is a swamp garden; and on the west side, an area of wetland and a boggy area called the Arena Garden. Finally, in the south of the garden, is a small bog garden or duck pond created for Bill Knott who liked ducks but found that they did not survive well at Glenwhan due to predators.

The Gardens

The gardens at Glenwhan exhibit many different garden habitats from moorland and woodland to water gardens, rock garden and scree ground. The planting is mostly naturalistic and has been described as being 'a fusion of styles – Antipodean, South American and Himalayan', and with 'a balance of evergreen and deciduous planting providing a solid structure to the beds and year-round interest' (Curtis-Machin 2006).

Large parts of Glenwhan Gardens have become woodland, interspersed with shrubs, trees, and in equal measure, rhododendron (Knott 2019). Glenwhan has more than 150 flourishing species and hybrid rhododendrons (Knott 2016). These include many of the hardy hybrid rhododendrons planted when the garden was in its infancy such as R. cynthia, R. phyllis korn and the R. loderi group (Underwood 2022). These provided the shelter needed for more tender species rhododendron and azaleas. Many of the species rhododendrons were grown from seed collected by the Cox's and other modern day plant hunters, including R. roxieanum from China and R. yakushimanum from Japan. Of particular note are the large-leaved varieties such as R. sinogrande which flourish within the shelterbelt woodland, as well as R. macabbeanum, and R. falconeri.

Hydrangeas have been planted widely as companion plants to rhododendron (Knott 2019), ensuring colour throughout late summer. Many of the Glenwhan examples have been propagated from the National Collection at Holehird Garden in the Lake District. Notable species at Glenwhan include the oak-leaved Hydrangea quercifolia from the USA, the drooping felty-leaved Hydrangea villosa, and the large, felted Hydrangea sargentiana from China. Other plants used as companions are Magnolia 'Star Wars'Pittosporum tenuifolium 'Elizabeth' with its pink-edged leaves, and the Giant Himalayan lily, Cardiocrinum giganteum, growing in gullies to emulate the conditions observed in Bhutan.

Planting of shrubs and trees has generally been kept away from water to preserve views. However, aquatic-loving plants flourish around the water garden and the Arena garden, such as the groves of Gunnera manicata from Brazil, planted as a massive group, and American skunk cabbage Lysichiton americanus. Various primula species, hostas and irises fringe the water garden and margins of the stream, while water lilies flourish in the lochans, and shrubs of Rosa rugosa fall down into the water.

The Potager is the only semi-formal area of the garden, located on lower ground east of Thinking Rock. It takes the roughly circular form of a decorative vegetable and flower garden divided into sections with low box and privet hedging,

The Moorland Walk is an adjunct to the main garden and arboretum, highlighting the contrast between the natural former moorland out of which Glenwhan Gardens were created over forty years ago (2023) with the garden in its current form.  Visitors can enjoy over 120 species of wildflowers and grasses, including native Scottish bluebells in spring, gorse, native fauna, also many birds of prey, insects, and red squirrels.


The arboretum at Glenwhan comprises over 160 specimens of broadleaved and evergreen trees within the shelterbelt, including species of oak, hazel, fir, cedar, pine, and Sequoia (Knott 2016). At the edges of the shelterbelt, are varieties of eucalyptus, the quick-growing Turkey oak, Quercus cerris, and the rare slow-growing conifer Brewer's weeping spruce, Picea breweriana, from the west coast of the USA. Meanwhile, different varieties of Sorbus are used as woodland companion plants, including S. insignis, introduced to Britain from Assam, northeast India in 1928, and the large-leaved S. sargentiana from West China (Knott 2019).

Other trees of particular note within the arboretum are birches grown in varieties including Betula 'Hergest' from China, and Wollemi pine, a critically endangered tree thought to be extinct before a small population was discovered in 1994 in the Blue Mountains of Australia ( A large collection of holly includes 20-25 named species of holly with examples from Lady Anne Palmer's collection at Rosemoor, Devon. Specimens of Scots roses climbing into trees provide added visual interest in places.

The arboretum also has many specimens of tender trees (Knott 2016). These include a rare weeping form of the Chilean Fire Bush, Embothrium coccineum 'Pendula' from Chile and Argentina, and evergreen Eucryphia from Chile, Australia and South America. Nearby on the east side of Glenwhan lochan is a Monkey Puzzle, Araucaria imbricata, while at the end of the tree trail, there are specimens of South American native trees, Drimys winteri v.latifolia and the holly Desfontainia Spinosa, from the rainforests of Chile with waxy, tubular orange flowers.

Near the house, a Monterey Pine (Pinus radiata) is a significant landmark tree, while a Montezuma Pine (Pinus montezuma), occupies a prominent location at the entrance to the gardens.



Historic Environment Scotland reference number CANMORE ID 374007 [accessed on 10 May 2023].

Maps and archives

Ordnance Survey 1st Edition 6-inch map Wigtownshire, Sheet 17 Survey date: 1846-47, Publication date: 1850. [last accessed 10 May 2023]

Ordnance Survey 2nd Edition 6-inch map Wigtownshire, Sheet 17 Wigtownshire Sheet XVIII.NE. Date revised: 1894, Date Published: 1896 [last accessed 10 May 2023]

Printed sources

Cox, K (2014) Scotland for Gardeners. Birlinn. Edinburgh

Curtis Machin, R (13 May 2006) The scent of impulse. The Glasgow Herald Magazine. Pages 60-61

Eburne and Taylor's (2006) How to read an English garden. Ebury. London. Pp. 241-4

Knott, T (2016) Glenwhan Gardens & Arboretum, Carved out of Scottish Moorland a plantswoman's finest achievement. Ziggurat Publishing.

Online sources

Britain's Finest (2023) Glenwhan Garden and Arboretum [last accessed 23 May 2023]

Galbraith, A (30 September 2019) Gardener's instinct. Scottish Field [last accessed 10 May 2023]

Glenwhan Gardens (2023) Glenwhan Tree Trail. [last accessed 18 May 2023]

Knott, T (2 September 2019) A Plantswoman's guide to gardening. Discover Scottish Gardens [last accessed 10 May 2023]

Knott, T (2019) Report from South West Scotland on Rhododendrons and Companion Plants suitable for the Milder Garden. Scottish Rhododendron Society Yearbook No 20 [last accessed 10 May 2023]

Underwood, R (Autumn 2022) Glenwhan Gardens Scottish Rhododendron Society No.89 [last accessed 10 May 2023]

Stevenson, A (4 August 2021) Starting from Scratch. The Scottish Gardener [last accessed 10 May 2023]

About the Inventory of Gardens and Designed Landscapes

Historic Environment Scotland is responsible for designating sites and places at the national level. These designations are Scheduled monuments, Listed buildings, Inventory of gardens and designed landscapes and Inventory of historic battlefields.

We make recommendations to the Scottish Government about historic marine protected areas, and the Scottish Ministers decide whether to designate.

The inventory is a list of Scotland's most important gardens and designed landscapes. We maintain the inventory under the terms of the Ancient Monuments and Archaeological Areas Act 1979.

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Glenwhan Gardens and Arboretum, looking from above in a southerly direction, over Glenwhan Lochan, with colourful planting in the foreground, and towards the coast at Luce Bay, on a cloudy day.
Glenwhan Gardens and Arboretum, looking in an easterly direction, over Glenwhan Lochan, with colourful plants around the edges of the loch, on a cloudy day.

Printed: 21/07/2024 06:25