Plant Heritage's Threatened Plant of the Year Award

Entries for 2025 can be submitted from 1 February (entry form will be available then).

Previous winner have included a rare camellia, growing in a back garden in Edinburgh, a peony bred by the renowned nursery Kelways, and a dwarf Clematis montana, selected from a plant collected in China over 100 years ago.

The entry criteria: Do you have an unusual, rare or special cultivar that is not currently available commercially? It must be a named cultivar that has been grown or sold in the UK or Ireland prior to 2015. 

Who could enter: Anyone (you do not have to be a Plant Heritage member) can enter up to 5 different cultivars.

Closing date: Wed 30 April 2024 

Competition time: Our research team will shortlist 12 plants for display at RHS Hampton Court Palace Garden Festival 1-6 July 2025 (plants or good quality images). Our expert judging team will announce a winner on the 30 June 2025 at our press day event at the show. Everyone whose plant is shortlisted are invited to attend. During the show week there will be a 'public choice' vote.                                  

2024 entries

Read about the Judge's Winner, the Peoples' Choice Winner and the 12 shortlisted entriesfor 2024, featured at RHS Hampton Court Palace Garden Festival.

The Judge's Winner

The judges' winning plant for 2024 is Aubrieta ‘Shangarry’ which is a fitting tribute to the late E. Charles Nelson, who dedicated significant effort to researching and documenting its history. E. Charles Nelson, a respected botanist and author, passed away in June 2024 while on holiday in Greece, but his legacy continues through his extensive writings and the plants he introduced to a broader audience, including Aubrieta ‘Shangarry’.

The Public Choice Winner 2024

The public choice winner for 2024 is Rhododendron 'Leonardslee Primrose', raised at Leonardslee by Sir Edmund Loder from a cross between R. campylocarpum and a white-flowered form of R. arboreum. This is now classed as an endangered cultivar, rarely if ever found in cultivation outside of Leonardslee.

Aubrieta 'Shangarry'

Aubrieta ‘Shangarry’ with pale lavender, double flowers resembling Parma violets is one of many notable cultivars that originate from the rich history of plant introductions from Ireland (Eire). It is mentioned in the significant work of the late E. Charles Nelson, A Heritage of Beauty – The garden plants of Ireland published in 2000 and encompassing 25 years of meticulous research into the rich history of Irish garden plants, highlighting the many cultivars that have contributed to Ireland's horticultural legacy.

Thanks to Nelson’s research we know that this cultivar was first listed in 1935 under the 'New and Unusual' section of the Ballawley Alpine Nursery catalogue and was also offered around the same time by Canon R.C. Patten of Fethard, of County Tipperary. Nelson suggests it may have been named for, or come from, Shanagarry, Co. Cork., indeed subsequent research shows it was later cited in Bulletin of the American Rock Garden Society (1955, Vol. 13) as 'Shanagarry'.

Camellia japonica 'Baronne Leguay'

Thought to be part of the display at Worth Park estate ever since the circa 1887 construction of its unique and beautiful Camellia corridor.  The flower itself is a marvel to look at with pink petals with light white strip in the middle of each one.

Listed in van Houtte’s catalogue of 1873-74 as introduced by Mons. Cachet of Angers, (France) whose nursery was described as 'Camellia nursery, par excellence, of Europe' in Johnson & Hogg's October 1861 edition of The Journal of Horticulture, Country Gardener & Country Gentlemen. His great skill was much admired, evident in the claim that nothing could be seen to equal such exceptional quality of plants.’  Though unconfirmed, naming suggests being for the wife of Albert-Léon Le Guay.

 Coleus 'Menthol Eucalyptus'

This tender perennial is loved by our entrant for its sensory value.  The short stems are covered by mounds of tiny, scalloped, fleshy pillow-like leaves. When a leaf is rubbed or crushed it has a strong menthol scent, which children, and adults both find fascinating. Its common name is Vick's plant, as some say it smells of Vicks VapoRub!

A very tidy plant which can be grown as a houseplant in winter and outside after frosts have passed. Easy to propagate and care for. A low maintenance plant perfect for the novice, with added menthol scent value. It thrives in a shady spot, great for those low light areas in the house.

Delphinium elatum ‘Conspicuous’

This cultivar has been grown by our entrant since their days as a student of gardening. Catching sight of this one at the RHS shows of the late 1970's sparked an interest in seeking out the many jewel-coloured cultivars of Delphinium elatum and so began a journey of connecting with many growers of Delphinium.

‘Conspicuous’ was introduced in 1917 by James Blackmore & Charles Langdon of Blackmore & Langdon’s, established since 1901 and specialising in the breeding of delphiniums and begonias. A beautiful lilac, mauve with a prominent dark eye. A medium variety (growing up to 1.5 m tall) with divided dark green leaves. Conspicuous was awarded an AGM in 1993.

Hemerocallis ‘Robert Coe’

A namesake bred in 1970 by Robert H Coe of Norton Hall Nursery, this plant is rarely found for sale.  There are few plants known to be still in existence.  

Originally described by Coe as being 40” tall with very large, reflexed, and ruffled flowers somewhere between fire red and burnt orange in colour, with a thin outline of orange on petals and a brilliant orange throat.

It is thanks to the research of previous National Collection Holders Gerald & Mary Sinclair that Coe’s legacy was gathered and conserved.

Iris 'Silvery Moon' (TB)

Hailed by our entrant as one of the loveliest of Sir Cedric Morris irises still in cultivation.  It was a gift from the late Elisabeth Wakeland Smith who lived nearby, who informed that it had been given to her by a friend who knew it was bred by Morris, but did not know the name.

Cited in the Toynbee Croftway catalogue of 1952 under ‘Croftway Nurseries. New Cedric Morris Varieties.’, with the description 'standards and fall white suffused blue, white and yellow inward flaring. Great interest was shown in this variety at the 1951 Iris Show.  3ft.'

Sir Cedric Morris had not registered the name and this plant is not to be confused with the tall, bearded (TB) iris bred by Georgia Hinkle of USA and registered in 1952.

Kniphofia ‘Modesta'

‘Modesta’, as befitting its name, is a small and slender poker with dainty grassy leaves. The flowers are creamy below and peachy coral above, about 60cm (24 inches) high. They appear in July and early August flowering reliably every year. A charming plant which was first offered for sale between the two world wars, and although its exact origin is unknown it is thought it may be a hybrid of the species Kniphofia modesta Bak. (K. parviflora Kunth).

Originally purchased from the renowned Elizabeth Strangman, of Washfield Nursery, Kent, in 1981, it has been in the entrant's garden ever since, outlasting many more modern cultivars and increasing slowly over the years.

Lilium ‘Ellen Willmott'

Named for one of the most eminent horticulturists of the late 19^th/early 20^th centuries, Ellen Willmott (1858-1934) of Warley Place. Raised by C. G van Tubergen of Zwanenburg Nurseries of The Netherlands and reputedly awarded a first-class certificate in 1898. Willmott had financially supported the plant collecting expeditions undertaken by the nursery and had maintained strong connections with one of the directors, John Hoog.

Our entrants plant came from Derek Fox of Bullwood Nursery, Essex around 1986. Derek, the author of Growing Lilies (1987), specialised in growing lilies, with a particular interest in Pacific Coast hybrids; of which he raised and named several introductions.

Polystichum setiferum ‘Gracillimum Cristulatum’

‘The last of its race and dates to before the first world war.’ Is what our entrant has to say about this very special fern which was collected from a garden in Buckinghamshire and the owner could trace it back to his granduncle’s garden.

The plant appears to be identical to the plant raised by Charles Druery, especially while it was in recovery after being so kindly given to me by Matt Busby of the British Pteridological Society (BPS) a year before he sadly passed away, he was very forward thinking. He commented it had been like the sword of Damocles for 30 years and had never produced a side crown, but it produced 2 bulbils last year and appears to be producing another this year. See Charles T. Druery’s British Ferns and Their Varieties originally published 1910.

Rhododendron 'Leonardslee Primrose'

Sir Edmund Loder is known for creating the Loderi group of hybrid rhododendrons at his estate in Sussex in the early 1900s, his work was continued by his widow after his death.

This hybrid was raised at Leonardslee by Sir Edmund Loder from a cross between R. campylocarpum and a white-flowered form of R. arboreum. This is now classed as an endangered cultivar, rarely if ever found in cultivation outside of Leonardslee.

Particularly interesting for its many small and delicate bell-shaped flowers of translucent primrose-yellow, spotted with maroon inside which appear throughout March and April.

Rosa 'Silver Lining' (HT)

First grown by our entrant in 1971 and much loved for its silvery pink well-shaped blooms on strong stems, it has the most delightful perfume. Awarded the Clay Cup for Scent in 1957, and a Gold Medal from the Royal National Rose Society (RNRS) in 1958 at a time when the popularity of the Hybrid Tea was at a peak.

Our entrant says it is ‘Sadly, lost to the catalogues of today, but still charming me!’ 

It was bred by Alexander (Sandy) Dickson III (1893-1975) of Newtonards, County Down.  The Dickson family are renowned breeders of roses in Northern Ireland, many of their introductions can be found listed in E.C. Nelson’s A Heritage of Beauty.

Salvia leucantha 'Midnight'

A favourite of our entrant due to its sensory nature. They describe it as having the a most amazing spikes of 'densely fuzzy, velvety purple flowers in abundance. It flowers from late summer to late autumn. Well worth the wait!’  They love the silvery undersides to the leaf, the upper leaf being a light green. During a breeze, it has a wonderful silvery shimmer to the whole plant that adds another dimension to an already fantastic plant.

Described in Betsy Clebsch’s 1997 A Book of Salvias as commonly seen in the gardens and nurseries of Arizona and California having been listed in catalogues for several years.

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