Delightful dahlias

Blooming prolifically from late summer until the first frosts, dahlias are the glamorous stars of the early autumn garden with their myriad colours and forms.

From the thousands of varieties trialled at Dyffryn in Wales in the early 1900s, to Agatha Christie’s collection, planted at Greenway in Devon during the 1950s (the flower even featured in one of her murder mysteries), we explore the dahlia’s fascinating horticultural history and its role in the creation of many of our gardens.

Freshly cut flowers from the Dahlia Garden at Anglesey Abbey, Cambridgeshire
Dahlias in a bucket at Anglesey Abbey, Cambridgeshire
Freshly cut flowers from the Dahlia Garden at Anglesey Abbey, Cambridgeshire

From Mexico to Europe

The myths around the history of dahlias are as complex and varied as the flowers themselves. Mexico’s national flower hails from the mountainous regions of Central America but the brilliantly-coloured blooms we covet today have come a long way from these native wild flowers.

In 1570, the scientist Francisco Hernández was sent to Mexico by King Phillip II of Spain to research the region’s natural history. Dahlias may have featured in his descriptions of over 3,000 plants then unknown to Europeans. But it wasn’t until the late 18th century, when botany was developing as a science, that dahlias were first cultivated in Europe. In 1786 a Spanish expedition returned to Mexico to complete Hernández’s work and dahlia seeds were among the plant material sent back to Madrid’s Royal Botanic Gardens.

It was here in 1789, that a botanist/priest named Antonio José Cavanilles began work on the collection. He published the first descriptions and drawings of three dahlia species, naming the new plants he raised after Andreas Dahl, a recently deceased Swedish botanist and pupil of Carl Linnaeus (the father of modern taxonomy). Seeds and tubers from these dahlias were widely dispersed to botanists and plant enthusiasts across Europe in the early 1800s.

Dahlias used in a mixed border at Nymans, West Sussex
Dahlias used in a mixed border at Nymans, West Sussex
Dahlias used in a mixed border at Nymans, West Sussex

Infinite variety

The first dahlias raised in Europe were single, open-centred flowers but horticulturalists soon discovered that when grown from seed, dahlias naturally hybridise, readily changing their colours and shape. This caused a particular headache for plant taxonomists trying to keep up with naming new varieties. Double dahlias were first bred in Germany in 1808 and growers quickly began selecting for specific traits. By 1820 around 100 dahlia varieties had been cultivated; in just twenty years that number had risen to 2,000. 

The Victorians loved dahlias with their exotic, richly-coloured blooms. When the Horticultural Society (later RHS) started regular flower shows in 1831, its September event was dedicated to dahlias. As they became the subject of serious competitions, the National Dahlia Society was set up in 1881. In the 1930s, at their peak of popularity, there were 14,000 named dahlia cultivars; over the last century, almost 50,000 varieties have been listed. 

The thousands of dahlia cultivars are classified by their different flower forms. There are 14 classification groups, including ‘collarette’, ‘waterlily’, ‘single orchid’ (star) and ‘fimbriated.’  

Telling a pompon from a cactus

Purple ball-type dahlia 'Nijinsky'

Pompon and ball

Pompon dahlias were reputedly named after the bobble on a French sailor’s hat. The tightly-packed, curled petals of these diminutive dahlias form perfect spheres. First bred in Germany in the 1850s, they appeared in Britain a decade later where they were known as ‘lilliputian’ or ‘bouquet’ dahlias. Ball dahlias are similar to pompons but slightly larger with a more flattened sphere.

The semi-cactus dahlia 'Kenora Sunset' in the dahlia garden at Anglesey Abbey

Cactus and semi-cactus

This dramatic dahlia revived interests in dahlia growing after it began to wane in the 1860s. Legend has it that all these forms originate from a single surviving tuber in a box sent from Mexico to Holland in 1872. This produced a large, fiery red flower with spiky petals, named Dahlia juarezii, in memory of Benito Juárez, Mexico’s recently deceased president.

Close-up with the petals of waterlily type dahlia 'Gerry Hoek' along the dahlia walk at Cragside

Waterlily (Nymphaea)

Delicate in appearance and almost saucer-shape, like its namesake, the term 'waterlily' was first adopted by a grower in New Jersey in 1893. The RHS initially listed these as ‘camellia-flowered dahlias’ in its first ‘Official Classification of Dahlias’ in 1921.

Dahlias at Dyffryn

When dahlias were trialled throughout the 19th century, the flowers were judged for their decorative qualities as specimens in the greenhouse or for floral arrangements.

Reginald Cory (1871-1934) the wealthy owner of Dyffryn near Cardiff changed all that. A keen horticulturalist and sponsor of plant collecting expeditions, he began the first trials of dahlias as garden plants in 1913, turning over most of his garden beds to thousands of different dahlias. These were judged by a joint committee of the National Dahlia Society and the RHS. 

After the First World War dahlia trials resumed and in 1923 Reginald sponsored the RHS Cory Cup for Dahlias. It continues today as a memorial cup awarded to the grower of the best hardy plant of garden origin. 

Given Reginald Cory’s knowledge of plants and his passion for the unusual and rare, it’s easy to see how dahlias captured his imagination. Dahlias can be found across different areas of the gardens at Dyffryn today. The modern collection features all 14 flower classifications as well as several of the species, including the giant tree dahlia, Dahlia imperialis.


" Dahlias are central to the history of Dyffryn gardens and Reginal Cory's sunken Dahlia Garden will eventually be restored."
- Chris Flynn, Head Gardener, Dyffryn Gardens
Rows of dahlias in early morning autumnal mist at Greenway, Devon
Rows of dahlias in early morning autumnal mist at Greenway, Devon
Rows of dahlias in early morning autumnal mist at Greenway, Devon

Agatha Christie's dahlias

Novelist Agatha Christie designed and planted a dahlia border at her holiday home Greenway on the English Riviera in Devon. She and her family spent late summer days here, just as the dahlias were beginning to bloom. Many of Agatha's original dahlia choices from the 1950s are still grown. The border sits in front of the putting green, where competitive games of Clock Golf were played.

Agatha even managed to weave the dahlia into one of her classic murder mysteries featuring her eponymous detective Miss Marple. In her short story, The Four Suspects, Miss Marple's knowledge of horticulture leads her to recognise some familiar dahlia cultivar names that appear in a riddle. The first letter of each name spells out the acronym DEATH and she's quickly able to name the murderer.

Semi-cactus dahlia 'My Love' combined with variegated ribbon grass in the Centenary border at Peckover House and Garden, Cambridgeshire
Semi-cactus dahlia 'My Love' combined with variegated ribbon grass in the Centenary border at Peckover House Garden, Cambridgeshire
Semi-cactus dahlia 'My Love' combined with variegated ribbon grass in the Centenary border at Peckover House and Garden, Cambridgeshire

Fashion victim

After over a hundred years of intense breeding, the last decades of the 20th century saw a decline in dahlias. Their popularity dwindled as gardening tastes changed. By the early 1980s, only around 20% of the thousands of dahlia varieties that had been available in the 1950s were still being cultivated. 

Fortunately, the cyclical world of fashion has come full circle again. Christopher Lloyd's Exotic Garden at Great Dixter, created in the mid 1990s, the National Dahlia Collection founded by David Brown and the restoration of many dahlia gardens and borders by the National Trust have contributed to dahlias being in vogue once more. They can be found in dedicated gardens, mixed borders, bedding and container planting in many of our gardens. Here's our pick of some of the best places to see dahlia displays this autumn.

There's a wonderful range of different colours and variety within the Dahlia Border

Anglesey Abbey, Cambridgeshire 

In 1952 Lord Fairhaven created a Dahlia Garden, dedicated to one of his favourite flowers and designed to impress his friends. The curve of the border makes it impossible to see the entire sweep of flowers in one go. Around 2,000 dahlias are grown annually from cuttings, with the main Dahlia Garden containing around 80 varieties planted in groups to provide blocks of colour. Others are used for bedding in the Formal Garden.

The Dahlia Walk at Biddulph Grange is a piece of mid-19th century garden theatre

Biddulph Grange Garden, Staffordshire 

Maria Bateman had a passion for flowers, so the creation of the Dahlia Walk, at a time when these plants were highly fashionable in Victorian Britain, must have delighted her. Divided by dramatic dark yew hedges, each bay is filled with colourful dahlias. The gardens team grow dahlia types which would have been available to the Batemans, such as single, anemone and pompon. They create a sea of colourful flowers at their best in September.

The decorative dahlia 'Glory of Noordwijk' growing at Cragside, Northumberland

Cragside, Northumberland 

Dahlias have always been grown at Cragside, home of Lord Armstrong, inventor and notable engineer at the forefront of technological developments in the mid-19th century. His wife Margaret was a major partner in the development of the gardens and fashion was a driving factor in the Armstrongs’ taste. In 1866, Henry Hudson was appointed head gardener and he was keen on showing dahlias. A dahlia border on the top terraces is filled with colourful blooms, put together in the spirit of Victorian eclecticism.

Dahlia 'Hollyhill Spiderwoman' being trialled at Dyffryn, Wales

Dyffryn Gardens, Vale of Glamorgan 

Dahlias can be found across the gardens at Dyffryn, adding drama to the Exotics Garden, providing late colour in the herbaceous borders, supplying cut flowers in the walled garden and stealing the show in container displays and in the formal bedding areas. Each year the gardens team bring in new cultivars to grow on in pots and in the dahlia trials bed to see how they perform, giving them the opportunity to find their star dahlias for the next season.

Dahlias growing by the head gardener's house in the walled garden at Shugborough

Shugborough, Staffordshire 

In 1805 Samuel Wyatt designed an impressive walled garden at Shugborough. A fine glasshouse showcased tender plants from around the world and pioneering cultivation techniques. Over time, it fell into decline and the glasshouse was lost. Until its eventual restoration, the gardens team are creatively re-imagining the glasshouse space using dahlias and a willow structure. The show-stopping display of colour and choice of flowers are a reminder of the exotic plants that once thrived here.

The dahlia beds in the walled garden at The Vyne, Hampshire

The Vyne, Hampshire 

Dahlias were an important part of horticultural life at The Vyne in the 19th century. Head gardener, Mr Broomfield, regularly won prizes for his blooms at local shows. Today dahlias are chosen to represent each of the classification groups. An area in the walled garden is divided into 35 beds, each planted with a different dahlia cultivar. Varieties are selected for their reliability and suitability for cut flowers, providing a colourful display until the first frosts.