Dahlia's Their History and Impact on Horticulture

A moth enjoying a visit to a Dahlia flower

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Introduction

In this article we review the history of the Dahlia flowers and their impact on horticulture. This popular genus of plants are grown for bedding and also for gardeners who like to compete in shows to display their prize blooms.

The Dahlia a poem by W.M. Martin

" Though sever'd from its native clime,

Where skies are ever bright and clear,

And nature's face is all sublime,

And beauty clothes the fragrant air,

The Dahlia will each glory wear.

With tints as bright, and leaves are green,

The winter in his savage mien,

May breathe forth storm,-yet she will bear,

With all, -and in summer ray,

With blossoms deck the brow of day.


And thus the soul-if fortune cast

Its lot to live in scenes less bright-

Should bloom amid the adverse blast;-

Nor suffer sorrow's clouds to blight,

Its outward beauty-inward light.

Thus should she live and flourish still,

Though misery's frosts might strive to kill

The germ of hope within her quite;-

Tghus should she hold each beauty fast,

And bud and blossoms to the last ".

***********************************************************************************************************************Dahlia's are named after Dr.Dahl, a student of Linnaeus and is commonly pronounced day-lia when a more correct pronunciation should be dah-lia. The small genus comprises herbaceous perennials which are native to Mexico and Central America.

They belong to the Asteraceae family of plants { formerly the Compositae} and may be distinguished from most others in that large family of flowering plants by the fact that the involucre is double , one series of green bracts being turned down towards the stalk while the other is pressed against the flower head. There is no pappus, but each floret has a dry, translucent bract at its base. The roots are fleshy and spindle shaped.




Dahlia Dahlstar 'Sunset Pink'

Creative Commons Attribution Share Alike 3.0 unported license
Creative Commons Attribution Share Alike 3.0 unported license | Source

Dahlia sambucifolia

One of the older varieties that helped to pioneer the varieties of today
One of the older varieties that helped to pioneer the varieties of today | Source

History of the Dahlia

The history of the Dahlia is relatively recent in terms of botanical introductions. Dahlia variabilis was discovered by Cervantes, the Director of the Mexican Botanic Gardens, and sent by him to his native country of Spain. from this stock the Marchioness of Bute introduced the Dahlia to England in 1789, however, the specimens failed, as did a supply obtained by Lady Holland in 1804. These were said to have been lost, because it was thought that a light sandy soil was the fitting medium for them to grow in, because they were originally encountered in sandy meadows at an altitude of 5000 feet.

In 1800, the Abbe Cavanilles by whom the genus was created, sent specimens of D.coccinea to Thouin, Professor of culture in the Museum d' Histoire Naturelle in Paris. These were the first Dahlias cultivated in France, and they were grown for their tubers, which were, however, rejected by both man and cattle. From this batch another consignment came to England in 1815, and with more liberal treatment succeeded and became improved and modified by cultivation.

Other species were introduced during the succeeding years, and many of these were a large component in the origins of the enormous number of varieties available today. these later introductions to england were D.excelsea. D.imperialis [1863} D. juarezii the Cactus Dahlia { which originated under cultivation in Mexico} and D.mercki {1839}

In the latter part of the 1800's a species called Dahlia superflua {Crimson fertile rayed Dahlia} was one of the parents that produced the fresh varieties which became one of the most popularly used ornaments of flower gardens in the autumn. It was raised from seed with the ease of an annual and the resulting varieties were multiplied and perpetuated with the certainty and extensiveness of a perennial. D.frustranea was one of the species used with the superflua but this plant was a more slender plant with narrower foliage, smaller flowers and a stem with a more conspicuous coating of whitish hoar termed bloom in fruit.

Both of these species grew to a height of seven or eight feet tall, with stems in proportion which were leafy and branched throughout. In England 'superflua' was classified as a tender outdoor plant, requiring a deep bed of rich mould for its successful cultivation and it was recommended that the roots were taken up and preserved from frost and the wetness of winter. In a sheltered place they were covered by dry sand or ashes. It was also recommended that the roots were divided in order to propagate the plant. great care had to be practiced by horticulturists to remove a part of the root-stock which contained at least one 'eye' or bud in the detached part.

Dahlia variabilis

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Cultivation tips.

Available to the modern gardener are a plethora of Dahlias. There are varieties for borders, tubs and other containers and species for those that like to display their blooms in flower shows. The family Asterales to which the Dahlia belongs, contain many of our favourite garden species such as Chrysanthemum and cone flowers. The Dahlia has been the national flower of Mexico since 1963.

The dwarf varieties have become very popular being much easier to grow and lack the need of time consuming staking. They fill the borders and tubs with superb colour through out the summer. These types are half hardy and need a sunny position and a well drained soil. All types apart from the dwarf types require staking.

Most gardens will produce a good show of Dahlias but to obtain the best from these plats they should be grown in a somewhat heavy rich soil. Gardeners that plan to grow Dahlias in a border should add manure, if required, the previous autumn or winter, other wise it will tend to produce an over luxuriance of foliage at the expense of flowers.

The taller varieties should be planted at the back of the border and as previously mentioned well staked.

The 'doubles' yield little in the way of seed and are mostly raised from cuttings or the division of roots. The ' singles ' produce seed freely. These are easier to germinate if they are soaked in water for a few hours before sowing them in a light compost in a tray preferably with a little gentle heat. Once germination has occurred the seedlings should then be potted singly. They will need hardening off gradually before being planted out at the end of May or the beginning of June {or when the danger of frost has passed}.

Cuttings are taken from young shoots just after they have started from the tubers, which have been placed in heat during February for the purpose of starting the growth. When the shoots have two joints they are carefully removed and potted singly in a sandy leaf mould. Placed in a cold frame they soon emit roots and need re-potting early, prior to being hardened off. These should be ready for planting out in June, Almost any number of plants can be raised from a few tubers in this way, saving the gardener a lot of expense, not having to purchase new ones from the nursery.

Another method of propagation more frequently adopted in small gardens, is to start growth from the collar of undivided tubers by placing them in heat in March, and then separating the tubers, making sure that each division has its own shoot. If these are potted singly, and grown until June, they will then be vigorous to plant in the open ground.

Delicate varieties may be propagated by grafting.

When the tops are blackened by the frost during the autumn they should be cut back to within a foot of the ground, the roots lifted with a fork, and the bulk of the earth removed without damaging the tubers. They should be dried in the fresh air, and stored in a cool, dry place until required for re-starting the following spring. Do not separate the tubers from the old stems for it is from this part of the plant that the new shoots will break.

Dahlia 'Karma Sangria '

This species was bred from the Cactus Dahlia.
This species was bred from the Cactus Dahlia. | Source

Possible cultivation problems

There are at least three common viral diseases of Dahlias of which the Dahlia mosaic is the most often encountered. The virus is very common and almost universal where Dahlia's are grown. Yellowish or pale green vein -banding on the leaves is the most usual symptom but on some cultivars it may be accomplished or replaced by some crumpling and twisting of the foliage and/or overall stunting of the plant. It is transmitted by aphids, but with a fairly short retention time. Thus insecticidal control is of little value, once plants are in beds. However, it is important while cuttings are being raised in an enclosed environment, such as a greenhouse, to pick off any aphids or affected foliage.

Although there is no overall solution to the problem, careful selection and multiplication from healthy plants is essential.

Dahlia and medicine

The species used in the past was D.variabilis. {Illustrated above} . the inulin found in dandelions and chicory is also present in Dahlias. herbalists used a special treatment that saw pure laevulose {sometimes called Atlanta Starch or Diabetic sugar} extracted from the tubers. In the past it was frequently prescribed for diabetic and consumption patients and given to children in cases of wasting illness.

Dahlia hybrid

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11 comments

D.A.L. profile image

D.A.L. 2 years ago from Lancashire north west England Author

VioletteRose, you are very welcome my friend, as you say,'Dahlias are beautiful plants and the history of plants has always fascinated me. Best wishes to you.


VioletteRose profile image

VioletteRose 2 years ago from Chicago

Dahlias are one of my favourite flowers, thanks for sharing so much information and excellent photos!


D.A.L. profile image

D.A.L. 3 years ago from Lancashire north west England Author

DREAM ON,

Thank you so much for your wonderful comments. They are truly appreciated. Hope your slumber was peaceful . Best wishes to you.


DREAM ON profile image

DREAM ON 3 years ago

I was in the most beautiful place with all your pictures.I didn't want to leave.Enjoying your hub so much I dozed off and took a nap.Wonderful read.


D.A.L. profile image

D.A.L. 3 years ago from Lancashire north west England Author

iamvinita, thank you for your visit and for your kind words. Best wishes to you.

aviannovice,

Hi Deb thank you your kind words and for visiting, best wishes to you.


aviannovice profile image

aviannovice 3 years ago from Stillwater, OK

These are some of the most stunning plants. Great work.


D.A.L. profile image

D.A.L. 3 years ago from Lancashire north west England Author

Jackie Lynnley Hi,

Thank you for your visit and your appreciated comments. Best wishes to you.


Jackie Lynnley profile image

Jackie Lynnley 3 years ago from The Beautiful South

They are a most perfect and beautiful flower. Great write, thank you.


D.A.L. profile image

D.A.L. 3 years ago from Lancashire north west England Author

RTalloni,

Hi thank you for your visit and for your kind comments. Good luck with your Dahlias along the fence. Best wishes to you.

iamvinita, Hi, Thank you also for your kind words. Best wishes to you


RTalloni profile image

RTalloni 3 years ago from the short journey

So interesting--thanks for this look at dahlias! They are one reason I enjoy gardening--it's such fun to use my southern accent when saying their name: daaahlias! :)

Seriously, I'm glad to learn more about this plant because I want to propagate my festively colored coral ones and make a bank of them along a fence.

Pinning to my Gardening: Flowers/Birds board.


iamvinita profile image

iamvinita 3 years ago

Just an excellent article!

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