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We grow a variety of dahlias in our ‘Flowers and their roots’ exhibit in the Outdoor Biome at the Eden Project, including:

  • Dahlia 'Bonny Blue' 
    In the mid 19th century a London newspaper offered £1 to the first breeder to produce a blue dahlia. The reward has never been claimed and breeders are still striving for the elusive blue colour. There have been several near blue cultivars including this ball-flowered type.
  • Dahlia coccinea 
    Introduced in 1789, this very variable species from Mexico occurs in the wild on rocky slopes, fields and roadsides. It was one of the first species introduced into Europe, to the Royal Botanic Gardens in Madrid from Mexico.
  • Dahlia imperialis 
    This variety is found in the wild from Guatemala to Colombia, where it can grow to 6m tall. It is very difficult to get it to flower outdoors in Europe before frost kills it.

Where it grows

Widely cultivated, although its native range is said to be from Mexico to Colombia.

Common uses

Dahlias can be used for dyeing. All dahlias (except the white flowers) produce warm yellows and oranges with an alum mordant and greens with iron mordants. A mordant is a substance that helps to fix the colours to textiles. If you deadhead your dahlias, why not collect them over summer and do some dyeing in the autumn?

Useful links


  • Herb: plant with fleshy parts rather than a persistent woody stem above ground.
  • Perennial: lives for at least two years. 
  • Subshrub: small shrub with woody and fleshy (herbaceous) parts. 
  • Tuberous: roots or stems fleshy and/or swollen.