RHS Lindley Library – Digital collections / RHS

Dahlias come in an amazing range of shapes and colours. There are more than 63,000 different cultivated varieties in the RHS Dahlia Register.

No flower has had more ups and downs in popularity. Although today it is a staple garden plant for late season colour, the dahlia was out of favour with the trendsetters in garden design for decades.

Discover the many faces of this fascinating flower with beautiful examples of dahlia art from the collections of the RHS Lindley Library.

Where do dahlias come from?

Dahlias grow wild in the mountainous regions of Mexico and Central America. Although the Spanish conquest in the early 1500s destroyed so much of Aztec culture, we know Aztecs had a sophisticated agricultural system and that they cultivated dahlias.

Image: Map of Mexico (Nueva Hispania tabula nova), 1548. Credit: David Rumsley Historical Map Collection.

In 1570 King Phillip II of Spain sent Francisco Hernandez to Mexico to study the natural resources of the country. He described plants that resemble dahlia species under the Aztec names Acocotli and Cocoxochitl. However these descriptions were not published for another 70 years and it took a further 140 years for dahlia plants to be introduced to Europe. It seems that the plant, which grew like a weed in Mexico, did not excite much interest at first.

Image: Cocoxochitl [Double Dahlia]. Engraving from: Francisci Hernandez, Rerum medicarum Novae Hispaniae thesaurus (Rome, 1648). Credit: RHS Lindley Collections.

In 1789 the director of the Botanical Garden at Mexico City sent seeds to Antonio Joseph [José] Cavanilles Palop, who worked at the Royal Botanical Garden of Madrid in Spain. From these he raised three different kinds which he named Dahlia pinnata, D. rosea, and D. coccinea. He named the genus after Andreas Dahl, a Swedish botanist.

Image: Illustration of Dahlia rosea, engraved by V. Lopez Enguidanos after an original by Antonio José Cavanilles, from Antonio José Cavanilles, Icones et descriptiones plantarum, Vol.3 (Madrid, 1794). Credit: RHS Lindley Collections.

These first plants were all single, open centred blooms with poor stems. Initially dahlias were grown under glass in Europe, until it was discovered that they could grow happily outside. Cavanilles sent seeds and roots to his horticultural and botanical friends across the continent. Dahlias reached the UK in 1803.

Image: Illustration of Dahlia pinnata, after an original by Antonio José Cavanilles, from Antonio José Cavanilles, Icones et descriptiones plantarum, Vol.1 (Madrid, 1791). Credit: RHS Lindley Collections.

Why are dahlias so varied?

Growers soon discovered that the dahlia was always ready to change its form, colour, habit and size. The dahlia is a natural hybridiser and dahlias grown from seed can display massive and unpredictable variety.

Nurserymen exploited this variation to select and propagate new forms and very quickly developed double-centred blooms. After its first introduction, there was an explosion in the range of shapes, colour and form.

Some varieties changed hands for as much as 100 guineas each. Only one colour eluded the breeders – a London newspaper offered a prize of £1000 to the first person who produced a pure blue dahlia. No one ever claimed the prize and modern science has shown that the genetic make-up of the plant mean it never can produce a true blue colour.

Image: Colour engraved plate of dahlias, from Samuel Curtis, The Beauties of Flora (Nottinghamshire: S. Curtis, 1820). Credit: RHS Lindley Collections.

Open in RHS Digital Collections

Popular early types of dahlia

The first forms of dahlia to be really popular were known as globe dahlias and later re-named ‘double show and fancy types.’ Show types were single colour and fancy types were a mixture of colours, sometimes as many as four.

Image: Sydenham Teast Edwards, Dahlia, watercolour on paper, undated. Credit: RHS Lindley Collections.

French growers experimented with new forms with a double row of florets, the inner row shorter in length than the outer. These dahlias were known as collerette varieties. French growers also developed tiny globular dahlias known to the English as Pompom.

Image: ‘Dahlias a Colleratte’. Dahlia ‘President Viger’, one of the first collerette dahlias, from a 1907 Rivoire catalogue. Credit: RHS Lindley Collections.

The country that took the dahlia most to its heart was the Netherlands. In the last quarter of the 19th century a Utrecht nurseryman imported a batch of small dahlia tubers from a friend in Mexico and amongst them he found one that offered a new and exciting form with petals that were long, narrow, rolled and pointed. This was the first cactus dahlia named Dahlia ‘Juarezzi’, after the President of Mexico at the time.

Image: Autochrome of red, yellow and pink cactus dahlias in a glass vase, taken by William Van Sommer. Credit: RHS Lindley Collections.

Open in RHS Digital Collections

The popularity of
dahlias at flower shows

Dahlias soon became a favourite flower to display at competitive flower shows. As there were so many different types, there were lots of opportunities for exhibitors to win prizes.

Dahlias could be grown to a high standard even on small plots of ground, so were very accessible to gardeners of modest means. Flower shows were enormously popular and although the prizes were small in value, growers devoted hours getting their blooms to a point of perfection.

Image: Dahlias on display at the RHS Hampton Court Palace Garden Festival, 2019. Credit: RHS / Luke Macgregor.

Breeders concentrated on producing flowers which met the strict criteria of the show judges. Even today, visit any flower show in any town or village during the months of August and September, and you are bound to see dahlias on display.

Image: Carte de Visite photograph of James Butcher dressing a dahlia. Credit: RHS Lindley Collections.

In some ways, the dahlia’s popularity and success was its downfall. The plant became seen as ‘common’, associated as it was with allotment and back garden growers, growing for competition.

The brightly coloured blooms, which were perfect for the exhibition hall, did not fit in with new fashion for more subtle, naturalistic garden design, perfected by designers like Gertrude Jekyll. Dahlias became seen by many as brash and garish, not really ‘garden-worthy’.

Image: Painted Lady Anemone-Flowered Georgina (Georgina variabilis var. Belladonna). From Robert Sweet, The florist’s guide, and cultivator’s directory, Vol.2 (London: 1827-29). For a brief period of time Dahlias were known as Georginas.Credit: RHS Lindley Collections.

Open in RHS Digital Collections

Dahlia ‘Bishop of Llandaff’

There was one dahlia that managed to sneak back in favour, with qualities that even the most fervent ‘dahlia phobe’ could not deny.

Image: Photograph of Dahlia ‘Bishop of Llandaff’ by Suzanne Drew, 2008. Credit: RHS / Suzanne Drew.

Dahlia ‘Bishop of Llandaff’ was first bred by Fred Treseder, a Cardiff nurseryman in 1924 and won the RHS Award of Garden Merit in 1928. Its dark foliage, vivid red, peony shaped flowers and ability to grow without needing staking made it the exception that proved the rule.

From this small start, dahlias began to edge their way back into our gardens. Over the past 15 years or so, more ‘Bishop’ dahlias have been introduced – Llandaff has been joined by Dover, Cardiff, Lancaster, Leicester, York and Oxford.

Image: Advertisement for the Cardiff nursery W. Treseder Limited, 1929. Credit: RHS Lindley Collections.

The garden design world really switched onto dahlias when influential gardener and writer Christopher Lloyd dug up the rose garden at Great Dixter in the early 1980s. He replanted with tropical plants, including orange, magenta and scarlet dahlias. He rejoiced in deliberately clashing colours and dahlias fitted the bill perfectly. Flower arrangers, led by Sarah Raven, also began to use dahlias, particularly the darkest reds to add drama to their arrangements.

Image: Undated photograph of the exotic garden at Great Dixter, East Sussex, taken by Patrick Taylor. Credit: Patrick Taylor / RHS Lindley Collections.

Dahlias today

Today the demand for dahlias continues to grow and breeders are developing new varieties every year. The process is painstaking. Even the most skilful hybridist might have to cultivate thousands of seedlings to find even one good new variety.

Image: Herbarium specimen of Dahlia coccinea. Credit: RHS Herbarium.

Open in RHS Digital Collections

Dahlia trials were traditionally an important way of establishing which new dahlia varieties held the most promise. For many years Wisley was an important centre for dahlia trials and samples from the trials were collected and prepared as specimens for the Wisley Herbarium.

Image: Members of the Dahlia sub-committee on the trials field, Wisley. Credit: RHS / Sue Drew.

Although permanent dahlia trials at Wisley were abandoned several years ago, a new dahlia trial is due to start on the new trial fields in 2021.

Image: Dahlia ‘Kilburn Fiesta’, a Semi-Cactus dahlia that arose as a chance seedling selected by Graham Hill, and was first offered for sale in 2010. This Herbarium specimen was collected from the RHS Dahlia Trial in 2012. Credit: RHS Herbarium.

What is the Dahlia Register?

The readiness with which dahlias hybridise to produce new forms and different combinations of colours rapidly led to the creation of many new varieties, even from the earliest times. A whole range of different flower forms were created - from true doubles in 1811 through to the orchid types just over 100 years later. The enormous number of new dahlias created a risk of confusion, with the same name given to different plants, leading to calls for a definitive list, or register.

Image: Detail of a nursery catalogue, published in France by François Cels in 1823, showing a list of dahlia varieties. Credit: RHS Lindley Collections.

Although the first Dahlia Classification Register was produced in Germany in 1833, it wasn’t until 1934 that the New York Botanic Garden compiled a comprehensive list of Dahlia cultivars. This volume included 14,000 different varieties, which equates to over a 100 new varieties a year since the first introduction of the genus. The rate, if anything, increased since then and we currently register up to 150 varieties a year. Dahlia breeding is genuinely international with new varieties being bred in the USA, Australia, New Zealand, India, Europe and even Japan.

Image: Illustration of dwarf dahlia types, by Augusta Innes Withers. From E. G. Henderson & Son, The illustrated bouquet, consisting of figures with descriptions of new flowers, Vol. 3 (London, 1857-64). Credit: RHS Lindley Collections.

The Dahlia Register and the RHS

In 1966 the Royal Horticultural Society was appointed the International Cultivar Registration Authority for Dahlia and the first International Register of Dahlia names was published in 1969. At present the Register includes over 63,000 cultivar names. The Registrar records the name, parentage, information about who raised the cultivar and who registered it, any awards it has received, as well as a description of the dahlia. All dahlias are assigned to one of 14 different horticultural groups in its official classification. In 2019 we made it possible for new cultivars to be registered online.

Where did dahlias originate?

Dahlias grow wild in the mountainous regions of Mexico and Central America. Although the Spanish conquest in the early 1500s destroyed so much of Aztec culture, we know Aztecs had a sophisticated agricultural system and that they cultivated dahlias.

Image: Map of Mexico (Nueva Hispania tabula nova), 1548. Credit: David Rumsley Historical Map Collection.

In 1570 King Phillip II of Spain sent Francisco Hernandez to Mexico to study the natural resources of the country. He described plants that resemble dahlia species under the Aztec names Acocotli and Cocoxochitl. However these descriptions were not published for another 70 years and it took a further 140 years for dahlia plants to be introduced to Europe. It seems that the plant, which grew like a weed in Mexico, did not excite much interest at first.

**Image:** Cocoxochitl [Double Dahlia]. Engraving from: Francisci Hernandez, Rerum medicarum Novae Hispaniae thesaurus (Rome, 1648). **Credit:** RHS Lindley Collections.
**Image:** Cocoxochitl [Double Dahlia]. Engraving from: Francisci Hernandez, Rerum medicarum Novae Hispaniae thesaurus (Rome, 1648). **Credit:** RHS Lindley Collections.

In 1789 the director of the Botanical Garden at Mexico City sent seeds to Antonio Joseph [José] Cavanilles Palop, who worked at the Royal Botanical Garden of Madrid in Spain. From these he raised three different kinds which he named Dahlia pinnata, D. rosea, and D. coccinea. He named the genus after Andreas Dahl, a Swedish botanist.

**Image:** Illustration of *Dahlia rosea*, engraved by V. Lopez Enguidanos after an original by Antonio José Cavanilles, from Antonio José Cavanilles, *Icones et descriptiones plantarum*, Vol.3 (Madrid, 1794). **Credit:** RHS Lindley Collections.
**Image:** Illustration of *Dahlia rosea*, engraved by V. Lopez Enguidanos after an original by Antonio José Cavanilles, from Antonio José Cavanilles, *Icones et descriptiones plantarum*, Vol.3 (Madrid, 1794). **Credit:** RHS Lindley Collections.

These first plants were all single, open centred blooms with poor stems. Initially dahlias were grown under glass in Europe, until it was discovered that they could grow happily outside. Cavanilles sent seeds and roots to his horticultural and botanical friends across the continent. Dahlias reached the UK in 1803.

**Image:** Illustration of *Dahlia pinnata*, after an original by Antonio José Cavanilles, from Antonio José Cavanilles, *Icones et descriptiones plantar*um, Vol.1 (Madrid, 1791). **Credit:** RHS Lindley Collections.
**Image:** Illustration of *Dahlia pinnata*, after an original by Antonio José Cavanilles, from Antonio José Cavanilles, *Icones et descriptiones plantar*um, Vol.1 (Madrid, 1791). **Credit:** RHS Lindley Collections.

Why are dahlias so varied?

Growers soon discovered that the dahlia was always ready to change its form, colour, habit and size. The dahlia is a natural hybridiser and dahlias grown from seed can display massive and unpredictable variety.

Nurserymen exploited this variation to select and propagate new forms and very quickly developed double-centred blooms. After its first introduction, there was an explosion in the range of shapes, colour and form.

Some varieties changed hands for as much as 100 guineas each. Only one colour eluded the breeders – a London newspaper offered a prize of £1000 to the first person who produced a pure blue dahlia. No one ever claimed the prize and modern science has shown that the genetic make-up of the plant mean it never can produce a true blue colour.

Image: Colour engraved plate of dahlias, from Samuel Curtis, The Beauties of Flora (Nottinghamshire: S. Curtis, 1820). Credit: RHS Lindley Collections.

Open in RHS Digital Collections

Popular early types of dahlia

The first forms of dahlia to be really popular were known as globe dahlias and later re-named ‘double show and fancy types.’ Show types were single colour and fancy types were a mixture of colours, sometimes as many as four.

**Image:** Sydenham Teast Edwards, Dahlia, watercolour on paper, undated. **Credit:** RHS Lindley Collections.
**Image:** Sydenham Teast Edwards, Dahlia, watercolour on paper, undated. **Credit:** RHS Lindley Collections.

French growers experimented with new forms with a double row of florets, the inner row shorter in length than the outer. These dahlias were known as collerette varieties. French growers also developed tiny globular dahlias known to the English as Pompom.

**Image:** ‘Dahlias a Colleratte’. Dahlia ‘President Viger’, one of the first collerette dahlias, from a 1907 Rivoire catalogue. **Credit:** RHS Lindley Collections.
**Image:** ‘Dahlias a Colleratte’. Dahlia ‘President Viger’, one of the first collerette dahlias, from a 1907 Rivoire catalogue. **Credit:** RHS Lindley Collections.

The country that took the dahlia most to its heart was the Netherlands. In the last quarter of the 19th century a Utrecht nurseryman imported a batch of small dahlia tubers from a friend in Mexico and amongst them he found one that offered a new and exciting form with petals that were long, narrow, rolled and pointed. This was the first cactus dahlia named Dahlia ‘Juarezzi’, after the President of Mexico at the time.

**Image:** Autochrome of red, yellow and pink cactus dahlias in a glass vase, taken by William Van Sommer. **Credit:** RHS Lindley Collections. Click to view in RHS Digital Collections.
**Image:** Autochrome of red, yellow and pink cactus dahlias in a glass vase, taken by William Van Sommer. **Credit:** RHS Lindley Collections. Click to view in RHS Digital Collections.

The popularity of
dahlias at flower shows

Dahlias soon became a favourite flower to display at competitive flower shows. As there were so many different types, there were lots of opportunities for exhibitors to win prizes.

Dahlias could be grown to a high standard even on small plots of ground, so were very accessible to gardeners of modest means. Flower shows were enormously popular and although the prizes were small in value, growers devoted hours getting their blooms to a point of perfection.

**Image:** Dahlias on display at the RHS Hampton Court Palace Garden Festival, 2019. **Credit:** RHS / Luke Macgregor.
**Image:** Dahlias on display at the RHS Hampton Court Palace Garden Festival, 2019. **Credit:** RHS / Luke Macgregor.

Breeders concentrated on producing flowers which met the strict criteria of the show judges. Even today, visit any flower show in any town or village during the months of August and September, and you are bound to see dahlias on display.

**Image:** Carte de Visite photograph of James Butcher dressing a dahlia. **Credit:** RHS Lindley Collections.
**Image:** Carte de Visite photograph of James Butcher dressing a dahlia. **Credit:** RHS Lindley Collections.

In some ways, the dahlia’s popularity and success was its downfall. The plant became seen as ‘common’, associated as it was with allotment and back garden growers, growing for competition.

The brightly coloured blooms, which were perfect for the exhibition hall, did not fit in with new fashion for more subtle, naturalistic garden design, perfected by designers like Gertrude Jekyll. Dahlias became seen by many as brash and garish, not really ‘garden-worthy’.

**Image:** Painted Lady Anemone-Flowered Georgina (*Georgina variabilis var. Belladonna*). From Robert Sweet, *The florist’s guide, and cultivator’s directory*, Vol.2 (London: 1827-29). For a brief period of time Dahlias were known as Georginas. **Credit:** RHS Lindley Collections. Click to view in RHS Digital Collections.
**Image:** Painted Lady Anemone-Flowered Georgina (*Georgina variabilis var. Belladonna*). From Robert Sweet, *The florist’s guide, and cultivator’s directory*, Vol.2 (London: 1827-29). For a brief period of time Dahlias were known as Georginas. **Credit:** RHS Lindley Collections. Click to view in RHS Digital Collections.

Dahlia ‘Bishop of Llandaff’

There was one dahlia that managed to sneak back in favour, with qualities that even the most fervent ‘dahlia phobe’ could not deny.

Dahlia ‘Bishop of Llandaff’ was first bred by Fred Treseder, a Cardiff nurseryman in 1924 and won the RHS Award of Garden Merit in 1928. Its dark foliage, vivid red, peony shaped flowers and ability to grow without needing staking made it the exception that proved the rule.

From this small start, dahlias began to edge their way back into our gardens. Over the past 15 years or so, more ‘Bishop’ dahlias have been introduced – Llandaff has been joined by Dover, Cardiff, Lancaster, Leicester, York and Oxford.

**Image:** Advertisement for the Cardiff nursery W. Treseder Limited, 1929. **Credit:** RHS Lindley Collections.
**Image:** Advertisement for the Cardiff nursery W. Treseder Limited, 1929. **Credit:** RHS Lindley Collections.

The garden design world really switched onto dahlias when influential gardener and writer Christopher Lloyd dug up the rose garden at Great Dixter in the early 1980s. He replanted with tropical plants, including orange, magenta and scarlet dahlias. He rejoiced in deliberately clashing colours and dahlias fitted the bill perfectly. Flower arrangers, led by Sarah Raven, also began to use dahlias, particularly the darkest reds to add drama to their arrangements.

**Image:** Undated photograph of the exotic garden at Great Dixter, East Sussex, taken by Patrick Taylor. **Credit:** Patrick Taylor / RHS Lindley Collections.
**Image:** Undated photograph of the exotic garden at Great Dixter, East Sussex, taken by Patrick Taylor. **Credit:** Patrick Taylor / RHS Lindley Collections.

Dahlias today

Today the demand for dahlias continues to grow and breeders are developing new varieties every year. The process is painstaking. Even the most skilful hybridist might have to cultivate thousands of seedlings to find even one good new variety.

**Image:** Herbarium specimen of Dahlia coccinea. **Credit:** RHS Herbarium. Click to view in RHS Digital Collections.
**Image:** Herbarium specimen of Dahlia coccinea. **Credit:** RHS Herbarium. Click to view in RHS Digital Collections.

Dahlia trials were traditionally an important way of establishing which new dahlia varieties held the most promise. For many years Wisley was an important centre for dahlia trials and samples from the trials were collected and prepared as specimens for the Wisley Herbarium.

**Image:** Members of the Dahlia sub-committee on the trials field, Wisley. **Credit:** RHS / Sue Drew.
**Image:** Members of the Dahlia sub-committee on the trials field, Wisley. **Credit:** RHS / Sue Drew.

Although permanent dahlia trials at Wisley were abandoned several years ago, a new dahlia trial is due to start on the new trial fields in 2021.

**Image:** *Dahlia* ‘Kilburn Fiesta’, a Semi-Cactus dahlia that arose as a chance seedling selected by Graham Hill, and was first offered for sale in 2010. This Herbarium specimen was collected from the RHS Dahlia Trial in 2012. **Credit:** RHS Herbarium.
**Image:** *Dahlia* ‘Kilburn Fiesta’, a Semi-Cactus dahlia that arose as a chance seedling selected by Graham Hill, and was first offered for sale in 2010. This Herbarium specimen was collected from the RHS Dahlia Trial in 2012. **Credit:** RHS Herbarium.

What is the Dahlia register?

The readiness with which dahlias hybridise to produce new forms and different combinations of colours rapidly led to the creation of many new varieties, even from the earliest times. A whole range of different flower forms were created - from true doubles in 1811 through to the orchid types just over 100 years later. The enormous number of new dahlias created a risk of confusion, with the same name given to different plants, leading to calls for a definitive list, or register.

**Image:** Illustration of dwarf dahlia types, by Augusta Innes Withers. From E. G. Henderson & Son, *The illustrated bouquet, consisting of figures with descriptions of new flowers*, Vol. 3 (London, 1857-64). **Credit:** RHS Lindley Collections.
**Image:** Illustration of dwarf dahlia types, by Augusta Innes Withers. From E. G. Henderson & Son, *The illustrated bouquet, consisting of figures with descriptions of new flowers*, Vol. 3 (London, 1857-64). **Credit:** RHS Lindley Collections.

Although the first Dahlia Classification Register was produced in Germany in 1833, it wasn’t until 1934 that the New York Botanic Garden compiled a comprehensive list of Dahlia cultivars. This volume included 14,000 different varieties, which equates to over a 100 new varieties a year since the first introduction of the genus. The rate, if anything, increased since then and we currently register up to 150 varieties a year. Dahlia breeding is genuinely international with new varieties being bred in the USA, Australia, New Zealand, India, Europe and even Japan.

The Dahlia Register and the RHS

In 1966 the Royal Horticultural Society was appointed the International Cultivar Registration Authority for Dahlia and the first International Register of Dahlia names was published in 1969. At present the Register includes over 63,000 cultivar names. The Registrar records the name, parentage, information about who raised the cultivar and who registered it, any awards it has received, as well as a description of the dahlia. All dahlias are assigned to one of 14 different horticultural groups in its official classification. In 2019 we made it possible for new cultivars to be registered online.

Created by RHS Lindley Library.

Based at the Royal Horticultural Society’s headquarters at Vincent Square in London, the Lindley Library holds a world-class collection of horticultural books, journals and botanical art.

Supported by the National Lottery Heritage Fund.

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