Dahlia


(Species: Dahlia spp.- Family: Compositae)

 

Dahlia and its origins

The Dahlia was first grown in Europe towards the end of the 18th Century, arriving in Madrid from its native homeland in Mexico. It is named in honour of the Swedish scientist Anders Dahl.  In the language of flowers, it can have diverse meanings being the symbol of the Omen but also, the Dahlia can be an advance in a declaration of love between two lovers.

Dahlia is the national flower of Mexico and was first observed there in the 17th century, however, it was another 200 years before it was cultivated in Europe.  Grown initially as a source of food thanks to its bulbous tubers, it wasn’t long before it became recognised for the rich, vibrant flowers produced.

Dahlia Merck and some of the smaller species are suitable to be grown in rock gardens. The other cultivated Dahlias are most commonly derived from crosses between Dahlia Coccinea and DahliaVariabilis, both of Mexican origin.

 

Seasonality: Dahlia in flower

Flowering from July to November, there are a diverse range of Dahlia species available, varying in colour, flower formation and size. 

There are two categories:

  • Dwarf varieties which grow from 20-50cm in height and with both single and double forms.
  • Tall varieties which can reach an impressive 1.7m high with large, showy, vibrant flowers.

Within the tall varieties of Dahlia, there are a number of other classifications:

  • Decorative large flowers with petals that reach 30 cm in diameter
  • Semi cactus cacti and flowers with petals defined by their long, narrow, pointed and often curved appearance which gives the impression of a windmill
  • Pompon blooms feature small, spherical flowers arranged in a symmetrical manner
  • A collar Dahlia has two rows of flowers, an external flower and internal flower which is stretched thin and much shorter
  • Simple flower which looks similar to a daisy

Typical Dahlia colours are vibrant and strong, ranging from whites and yellows to pinks and red amaranth.

 

How to Plant: Dahlia

Dahlias are relatively easy to grow and as a result are a common sight in gardens, particularly in northern Europe and the United States.

These plants thrive in climates that are warm; they do not tolerate frost.  For best results plant in a light, bright area, in soil that is rich in humus or well fertilised.  The soil should be fairly loose to allow for good drainage and prepared a month before the tubers are planted, mixing with organic fertiliser if necessary.  If the soil is not loose enough add a good quantity of sand.

Ideally, Dahlias should be planted in late March or May in colder regions.  The distance between tubers is dependent on the species varying from 30-70cm.  Planting the tubers a little deeper in colder climates, approximately 10-15cm, also helps to protect them from any late onset frosts. 

Generally, the Dahlia requires minimal attention; removing the weak stems when they reach 10 cm. High and leaving 3 stems when they reach 20 cm. Large-flowered varieties require a brace to support the stalk.

 

Propagation of Dahlia

Dahlia can be propagated with ease and taken from shoots or tubers.  When dividing the tubers ensure that it has a viable bud.  Each tubers should start growth in a warm place, ideally indoors in early spring.  If planted in a moist well-drained compost, they will start to grow shoots in a couple of weeks and are ready for division when they reach 2-3cm. 

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