Importance of Site
A site included in the Inventory is assessed for its condition and integrity and for its level of importance. The criteria used are set out in Annex 5 of the Scottish Historic Environment Policy (December 2011). The principles are represented by the following value-based criteria and we have assigned a value for each on a scale ranging from outstanding value to no value. Criteria not applicable to a particular site have been omitted. All sites included in the Inventory are considered to be of national importance.
Work of Art
The gardens have high value as a Work of Art due to the design of the garden glades flowing along the slope of Kelton Hill.
The gardens have been created since 1960 and thus provide only a little Historical value.
Horticultural, Arboricultural, Silvicultural
The large collection of plant material gives the gardens outstanding Horticultural value.
The designed landscape at Threave provides the setting for architectural features which together give it high value.
The woodland and the specimen trees provide some Scenic significance in the wider agricultural landscape.
The woodlands at Threave provide a little Nature Conservation value.
- Not Assessed
The designed landscape was laid out by William Gordon in the 1880s and the majority of the garden has been created since 1960. There are no known landscape designers.
In 1872 William Gordon, a successful businessman from Liverpool, built Threave House, taking the name from a 12th century castle situated on a island in the River Dee within the bounds of the estate. His grandson, Major Alan Gordon, approached the National Trust for Scotland in 1948 and the whole estate was finally transferred to the Trust on the death of Major Alan Gordon in 1957. In 1960 the Threave School of Gardening was set up to train amenity gardeners, providing a two year residential course. Eight students are accepted each year and all the accommodation and classrooms are provided in the house. Much of the garden has been created since 1960 under the guidance of the principal of the school, Mr W. Hean, and has been constructed by the students.
Threave House, listed category C, was designed by Peddie and Kinnear in 1872 and now houses the National Trust for Scotland's school of gardening. The Walled Garden and stable-block were probably built at the same time as the house. Several cottages were built in the 1960s for the school's staff. The Visitor Centre was built in 1975. The Japanese lantern came originally from Inveresk House.
The majority of the parkland has been converted into part of the garden but there is a small section to the south of the entrance drive shelterbelt which contains two clumps of trees, mainly hardwoods of about 100 years old.
Kelton Wood is made up of an outer ring of hardwoods planted in c.1870 of mainly beech, oak and ash; the central core is predominantly softwood, larch and spruce, planted in 1973.
The gardens were created on the south-west facing parkland and there are still one or two large clumps of beech providing structure for the new planting. There are fourteen different areas described in the guidebook and the majority have been planted up since 1960 as demonstration borders for the students. They include a rose garden, woodland garden, patio nursery, peat garden, rock garden, vegetable garden, walled garden and greenhouses, pond and water garden, dwarf conifers, secret garden, herbaceous borders, arboretum, heather garden, orchard, crab-apple and cherry collection and bog garden. The Gordons naturalised many thousands of daffodils and many of the older varieties still flower in the open lawns.
The designs of the gardens have evolved from the semi-natural woodland garden style to the more sinuous open glades made from lawns in which the plants are grouped together in irregular and flowing shaped beds. This style of gardening is typical of the 1960-70s. In every section of the garden the widest range of plants has been used and Threave contains the National Collection of Penstemons as well as a particularly fine collection of alders and Narcissus. When Alan Mitchell measured the trees in 1984 he included over 165 different specimens. The gardens are well described in the guidebook and in two articles in Country Life. Plants for sale at the Visitor Centre and at other NTS properties are raised in both the walled garden and the forestry nursery.