Dahlias (Dahlia) – a genus of perennial herbaceous tuberous plants of the Compositae or Asteraceae family. Includes up to 35 species, grows wild in a number of Central American countries.
- Family: composite (Compositae) or aster.
- Genus: dahlia.
- Origin: Mexico, Colombia, Guatemala.
- Rhizome: storage roots (corms or tubers).
- Stem: branched, straight, hollow.
- Leaves: Opposite, compound, pinnate.
- Fruit: achene, up to 140 seeds per 1 g.
- Reproductive ability: propagated by dividing tubers, cuttings, sometimes seeds
- Illumination: photophilous.
- Watering: rare, but plentiful.
- Content temperature: thermophilic, does not tolerate negative temperatures.
- Flowering time: from July to frost, for 90 days.
Everywhere in gardens, varieties of one of the species are grown – cultural or diverse dahlias (D. variabilis). This is a perennial flowering plant with storage roots (root tubers). In the conditions of the middle lane in the open field does not hibernate. The stems are straight, branched, 30 to 250 cm high, hollow in the internodes, woody at the base. They have a reproductive part: an aerial shoot carrying a productive organ, an inflorescence, and a vegetative part: the so-called root collar. In the axils of the lower leaves of the root neck, renewal buds are formed, from which shoots of the current year develop. The reproductive part of the stem dies off annually at the end of the growing season. The life span of the vegetative part is 2-3 years, and the storage roots of dahlias live for about 5 years. On the shoots of the current year, new root tubers are formed annually, and the tubers of past seasons increase in size from year to year.
The leaves of the dahlia are opposite, odd-pinnate, sometimes simple, of varying degrees of pubescence, mostly dark green, rarely red-brown.
The inflorescence is a basket with a diameter of 3 to 30 cm, along the periphery of which there are pistillate reed flowers, very decorative, diverse in shape, size and color, and in the center there are tubular bisexual flowers, mostly yellow or brown, very small, sometimes large, various coloring. At present, through the efforts of breeders, varieties have been created in which the inflorescence consists only of non-fertile reed flowers, as a result of which the dahlia flower becomes denser, fuller, sometimes even spherical in shape.
History of dahlias
In the wild, dahlias grow in the mountainous regions of Colombia, Mexico, and Guatemala. The first description of the dahlia belongs to the Spanish doctor F. Hernandez, who lived in Mexico, who in 1615 in his writings called this flower by the local name “acocotla”.
The plants were brought to Europe by Spanish travelers and at first they were tried to be used as an edible vegetable, like potatoes. However, Europeans did not like the taste of tubers, unlike flowers.
In 1791, the director of the Madrid Botanical Garden named the new plant dahlia after his friend, the Swedish botanist Anders Dahl. In 1803, the German botanist Karl Ludwig Wildenow proposed giving the flower a different name “dahlia” (Georgina), in honor of the botanist from St. Petersburg, academician Johann Gottlieb Georgi, arguing that the name “Dahlia” already has one of the South American shrubs. For some time, both generic names existed in parallel, then it was customary in botanical literature to call the flower “Dahlia”. The second name is firmly entrenched only in Russia, and since then we have known this flower as a dahlia.
In the beginning, dahlia flowers were considered tropical plants and were grown only in greenhouses, and gained popularity only after the French scientist De Candol planted individual specimens in the soil of the botanical garden in Montpellier. The grown flowers were so good that they quickly spread among amateur flower growers. Already in 1808 in Germany, the first terry varieties with large flowers were bred, and in a few years breeders received plants of all possible colors, spherical and semi-double (anemoid), small decorative varieties appeared. Flowers have firmly become fashionable, they were purchased for their gardens by the most noble persons for a lot of money. In the 19th century the number of varieties reached 3000. New forms appeared – cactus, collar. True, the hybrids of that time had a significant drawback – heavy inflorescences were weakly held on short peduncles, in addition, they were covered with leaves. Therefore, before the First World War, a new species was involved in the process of breeding new varieties – Merck’s dahlia (Merckii). It was from her that the modern dahlia inherited strong flower stalks, towering above compact leaf bushes.
Dahlia as a decorative culture
Currently, dahlias are still just as popular. None of the modern garden flowers can boast such a variety of colors and sizes. Among them, there are dwarfs about 30 cm high and giants taller than human height, the diameter of the inflorescences ranges from 3 to 30 cm. In total, there are several tens of thousands of dahlia varieties in the world. It is impossible to convey all the currently existing colors and shades, shapes and varieties of flowers in a photo in one article.
This plant is suitable for both the beginner and the experienced gardener. It is quite unpretentious, loves the bright sun, but puts up with partial shading, it grows better in a separate flower bed, but it will feel good in a grassy border. Even with minimal care, which consists in planting last year’s dahlia tubers at the end of May, which were stored in the garage in winter, tying up the grown shoots and treating the leaves from diseases and pests, you can get a wonderful result. At the same time, for an experienced grower, growing this plant can be an exciting hobby. By applying a number of special care techniques, you can achieve, for example, record-breaking inflorescence sizes, or record-breaking early flowering.
Winter storage of dahlias and diseases
Dahlias do not hibernate in the ground in our climate, therefore, after digging in October, the tubers are dried and prepared for winter storage. Plants are carefully inspected and culled specimens affected by such dangerous dahlia diseases as bacterial cancer (growths at the root neck and on tubers) and sprouting (short thickened shoots at the bottom of the stem). They are subject to destruction, as they are not amenable to treatment.
Some authors recommend treating dahlia tubers with any systemic fungicide before storing, powdering the roots or even immersing them in an aqueous solution of the drug, to which experienced flower growers also add a systemic insecticide. When using a liquid solution, the roots are kept in it for 15 minutes. You can immediately discard those tubers that do not sink, but float to the surface – they will not be preserved until spring. After this procedure, the planting material is dried and stored for winter storage.
The most common way to store dahlias is in boxes with sand at a temperature of + 1-10 ° C in a dry, ventilated room. If it is possible to maintain humidity at the level of 80-100%, the tubers can not be covered with sand.
When storing dahlias in dry and warm rooms, such as heated basements or city apartments, the planting material is packed in small plastic bags, sprinkled with an insulating material, such as peat, and tied tightly.