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26 Apr 2024

The PLANTS project: the Brodick audit

Written by Dr Colin McDowall, PLANTS Project Manager
A large group of Trust gardeners, all wearing navy jackets, stand in front of some ferns and a tall flowering rhododendron in Brodick Castle Garden. The castle can just be seen in the distance.
The PLANTS Project team in the Pond Garden, Brodick Castle
As we enter the final year of the PLANTS project, the whole team travelled to Brodick Castle, on the Isle of Arran. Like many others, this audit revealed wonderful stories about the people, history and collections of a remarkable place.

Brodick Castle Garden

Brodick Castle, the ancestral home of the Dukes of Hamilton, has a magnificent 65-acre garden and over 7,000 acres of mountainous landscape surrounding the castle and garden. The Atlantic Drift, which moderates the climate of Scotland’s west coast, has made it possible for plants from Asia and South America to feature here. There are three nationally recognised Rhododendron collections (sub-sections Falconera, Grandia and Maddenia), many recorded champion trees and a number of rare and endangered rhododendrons at Brodick Castle. The Duchess of Montrose started the collection around 1920, seeking out seeds and plants from other notable gardens. The collection was expanded and enriched by generations of plant collectors (Reginald Farrer, Francis Kingdon-Ward, George Forrest, and Frank Ludlow and George Sherriff to name a few).

Founded on deep, slightly acidic soil, the garden benefits from numerous outcrops of red sandstone that provide shelter. The PLANTS project’s aim is to ensure this major plant collection is properly recorded for the future in our plant catalogue database (IrisBG).

Plant auditing

The PLANTS team is made up of 4 smaller regional teams (North, East, West and Central – see our PLANTS page for more info). Due to the size and complexity of the plant collection at Brodick, this garden audit presented the opportunity to allow all the teams to come together to ensure the audit was completed successfully.

As with all our audits, the team manager – in this case Jennifer Hollywood from the West team – spent the prior winter months liaising with garden management staff to gather as many of the records, maps and other information relevant to the audit as possible. Brodick had a number of data sets (an Excel list of new accessions and information from a previous tagging project) that were processed and either entered into our database beforehand or prepared to use in conjunction with the on-site survey. Jennifer also did preparatory Health and Safety work, and came up with a flexible priority plan for auditing the garden.

The audit itself began on 26 February with a health and safety debrief from the property’s Head Gardener, before a tour of the garden to understand the geography and areas to focus on. For the majority of gardens, we also work from maps illustrating the locations of garden beds – but in a garden the size and scale of Brodick it can be a challenge for a newbie to identify the boundaries between individual areas. The garden team provided practical help by using bamboo sticks to define boundaries for us.

Having defined the scope of the audit, we got to work. As discussed in my last blog post, auditing alongside garden staff is a huge help to the PLANTS team. At Brodick we were fortunate to have support from Head Gardener Donald Guthrie and Assistant Head Gardener John Nicolson. Their enthusiasm for the collection and their willingness to answer queries were very beneficial.

Brodick hadn’t had access to a database for many years, and there were quite a number of new plantings to record. Time and again, I was grateful for John guiding me carefully through the undergrowth to show me the location of a plant. One that stands out particularly was Cephalotaxus harringtonia, a rare evergreen shrub in the yew family, commonly known as Japanese plum yew.

Each day on an audit we carry with us a printed list of which plants are present in the beds that we are working on. This list is produced from our database and includes what has been recorded in that location with its status (alive, dead or unknown), and any other helpful identification or location information.

People are often surprised to learn that the majority of plants within Trust gardens have an ‘accession’ number against them in our database, a unique number sequence which links each plant to its catalogue record. If you visit Brodick Garden regularly, you may have noticed the black and white plant labels, which include the plant name and the geographical area where the plant species can be naturally found. These labels are not only a convenient way to provide information to the public; at Brodick, some of them revealed key information that helped us to correctly identify and record the collection!

A key part of every audit is to confirm that what is recorded on the garden’s plant database (IrisBG) matches what is found on the ground. Unfortunately, this is sometimes easier said than done. With 900 species and over 30,000 named cultivars, the identification of Rhododendron is often a task left to a handful of highly skilful experts. In the bottom left of several Rhododendron plant labels at Brodick is ‘V. (A. Clark)’. The ‘V’ indicates that the plant identification has been verified by Alan Clark, who was a rhododendron expert.

I was excited to find a previously unidentified Rhododendron sp. being verified by Alan Clark as Rhododendron saluenense; it was one that he himself had introduced to the garden in 1991. At the end of the project, a defined and targeted list of rhododendrons still needing verification will be produced.

Another label that you may see on some plants in Trust gardens (and included in the picture above) is an oval metal numbered tag. These are used extensively on shrubs and trees in some gardens to help track specimens. Having this tag information up-to-date in the database will mean that a gardener can quickly link the plant material on the ground to various data and information resources.

Some plants at Brodick also feature a special blue label, with the letters ‘HC’ and a unique number in the bottom right. These labels are found on Rhododendrons originating from the collection of Sir James Horlick, an accomplished plantsman who bought the Isle of Gigha in 1944. There, he and gardener Kitty Lloyd Jones created Achamore Gardens. Like Arran, Gigha enjoys a mild climate that is ideal for growing rhododendrons, camellias and tender exotics. In 1962 Sir James gifted an important collection to Brodick Castle, and part of our audit focused on assessing the rhododendrons that had been grown from these original Achamore plants. I am pleased to say that the team reconfirmed the existence of many Horlick plants, as well as finding some whose location within the garden had been previously unknown.

Plant discoveries

On my first day at Brodick I was pleased to encounter a Rhododendron hodgsonii that originated from the Horlick collection. From the eastern Himalayas (Nepal, Sikkim and Bhutan), this species has beautiful, pink, papery bark, and its wood is used for making cups, spoons, ladles and yak saddles. Another Horlick original also caught my attention: a fine Rhododendron arboreum specimen with large red flowers that towered above us as we audited. Another Himalaya native, this time collected by Kingdon-Ward and planted by the Duchess of Montrose, the Rhododendron montroseanum was particularly captivating.

As we audited the path to the Cnocan Gorge area, we were amazed to find such beautiful specimens as the one pictured below, which requires further identification. Another highlight of the gorge was the spectacular display put on by the pink flowers of Rhododendron magnificum. This species is frost-intolerant and therefore rare in cultivation, but it survives at Brodick due to the protection of the gorge. Another tender rhododendron I was much taken with was Rhododendron spinuliferum ‘Blackwater (pictured below), which has tubular red flowers with protruding stamens.

Never one to miss out, my 2-year-old daughter came for a visit and was particularly taken with the large-leaved Rhododendron subsection Falconeri.

Finally, I could not forget to mention the rhododendron named after the garden itself: Rhododendron arizelum ‘Brodick(pictured below). It is relatively slow-growing and takes ten years or more to flower. Further investigation found that the cloneBrodick’ is rare in cultivation and received an Award of Merit from the RHS in 1963.

As always when finishing an audit, I am impressed by the collection’s connection to the past. I was amazed to learn from John that Major Boscawen – the son-in-law of Lady Marie Louise Hamilton, Duchess of Montrose – organised a whole steamship of plants to be brought from Tresco Abbey Garden (which belonged to his uncle). At Tresco there are fine examples of Phyllocladus trichomanoides, commonly known as the celery pine of New Zealand. I came across the same plant at Brodick and admired its celery-shaped ‘leaves’ (not true leaves – phylloclades are flattened branch projections which take on the forms/function of leaves and appear as tiny brown scales early in their development.) It’s a pretty remarkable plant.

Cabbage palm (Cordyline australis) as well as fine mature specimens of Cordyline banksii and Cordyline indivisa were also found in the garden. By the nursery I was amazed to find a Cordyline australis which, at over 13m, is the Girth & Height Country Champion of Scotland. It wasn’t the only award-winner in the garden; the Girth & Height County Champions of North Ayrshire Cunninghamia lanceolata and Eucalyptus urnigera watch over the play park.

Trees and shrubs from the most temperate regions of the world – particularly China, the Himalayas, New Zealand, Tasmania and Chile – all thrive at Brodick. The Ugni molinae (Chilean guava) and Pinus ayacahuite (commonly known as the Mexican white pine or ayacahuite) were exciting plants to see. I particularly loved the long needles of the Pinus – up to 18cm!

Native to Eastern Afghanistan and Western China but rare to the UK, Quercus semecarpifolia is an unusual evergreen tree that is frost tender and whose new leaves turn orange as they emerge. A plant that was new to me was Asteranthera ovata, a tiny shrublet that John brought to my attention. It scrambles through the forests of Chile and is just about hardy in the UK. A final Chilean plant whose identification temporarily stumped the team was Caldcluvia paniculata. It was a surprise discovery for Brodick’s garden team as well as they hadn’t known it was present in the garden. The plant has been carefully recorded and tagged for the future.

Overall, the PLANTS team did extraordinary well at Brodick. We battled storms, wind and cancelled/delayed ferries to complete the audit for the majority of the collection. Just over 4,000 plants were inventoried by the team, and the West team will return this summer to audit the herbaceous plants. Our thanks go to the Brodick team for their warmth, humour and cake over the three weeks.

Next time you’re on Arran, make sure to give the garden a visit!

Plant Listing at the National Trust for Scotland (PLANTS) is the biggest horticultural audit project undertaken by the Trust and aims to celebrate, protect and better understand the flora and vegetation across our gardens and designed landscapes.

Read more about the PLANTS project

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