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Dahlia Culture

Classification

Single, Semidouble

Double-Flowered

Culture and care
Dahlia Culture

Dahlias are easy to grow.
They are grown on a lot of different places in many countries of all the continents.
And they are grown in all kinds of soil.
On these pages we want to offer helpfull information to help them grow even better.

To start with we will tell some about the origin of the dahlia, the history of cultivation, the classification of all those different types of dahlias and the general growing guidelines.
Bishop of Llandaff DAHLIA.....

Everyone loves them,... anyone can grow them!
The dahlia is one of the prettiest and most versatile of ornamental plants. In the extensive colour range offered by dahlias, the only colours missing are true black and blue. They often display two colours as well. And besides their many bright colours, dahlias are also appreciated for the many shapes they can have.
Various floral shapes range in size from 2 to 3 centimetres across to true giants more than 30 centimetres in diameter. The many cultivars also offer a wide scope in height, the shortest being just 20 cm and the tallest able to reach almost 2 metres. Besides dahlias with green foliage, there are also varieties with very decorative maroon leaves. With all this variety, dahlias offer many uses.

ORIGINS

Dahlias belong to the Composite Family (Compositae). The genus Dahlia has twelve species, all native to Central America, especially Mexico. The first written descriptions of them were made by Francisco Hernandez in 1615. It was around this time, too, that the first seeds were taken from Mexico to Spain.
Gallery Leonardo
Pinnata It was not until about 200 years later - in 1804 to be exact - that the dahlia was really introduced and was named for Andreas Dahl, a botanist and a student of Linneus. During this time, you could find dahlias at such locations as the botanical gardens of Madrid and, later, in Berlin.
Then, dahlias spread throughout Europe and people started crossing and selecting them. These first dahlias were hybrids of the various original wild species and were named Dahlia variabilis. The specific epithet, variabilis, refers to the species' wide range of floral colours and shapes. This trait is based on the fact that dahlias are octoploids (they have eight sets of homologous chromosomes bearing hereditary factors, whereas most plants have only two sets). This explains the sometimes extremely divergent results obtained from crossing them. The most important species in the history of breeding is D. pinnata (syn. D. rosea). Also contributing to the large assortment we have today were D. coccinia and D. gracilis, with D. juarezii being known as the forefather of the Cactus dahlias.
In 1810, the cultivation of dahlias started to develop in the Netherlands. In 1813, a grower by the name of C. Arentz in Leiden had bred one of the first entirely double flowers. Arentz was truly one of the pioneering dahlia growers in the Netherlands: in 1819, he was already offering an assortment containing about 70 varieties (colours). Since that time, many people who became fascinated with this plant have succeeded in crossing many, many cultivars in all kinds of variations. It is estimated that 20,000 different kinds have been developed, but this number could be much higher if we count the ones developed all over the world.

Then, about 100 years later, the Netherlands Dahlia Society was founded in 1918. Its most important goal was (and still is) to encourage the cultivation of, the trade in, and the export of dahlias. The association consists of both amateurs and professional growers and devotes a major part of its energies to promotional activities in the Netherlands and abroad in the form of organising and participating in indoor and outdoor expositions, as well as the holding of field and flower inspections and establishing the regulations for these inspections.

By that time, the cultivation of dahlias had become so widespread and popular that guidelines and regulations were necessary. To make the many different types of dahlias more accessible to the public, the assortment was classified into a certain number of groups. New cultivars were then registered according to this classification as set up by the guidelines of the Royal Horticultural Society, an organisation that is internationally accepted as the authority for the registration of many ornamental plants, including the dahlia. Within the Netherlands, the registrations are conducted by the Nomenclature Department of the Royal Dutch Bulb Growers' Association (KAVB). The varieties are planted at this association's Testing and Specimen Garden, so that the various characteristics of the variety can be assessed during a growing season.
 
Update: 23 november 2015       text and photographs   Verwer Dahlia's bv Lisse, NL