Dahlias are propagated by dividing root tubers and cuttings. Dahlia cuttings can be carried out starting in January-February. However, the optimal timing begins in early March and lasts until early April, when natural light improves.
Early grafting makes sense in the presence of additional lighting with phytolamps, and is more often used if you want to get the largest amount of planting material.
Plants grown from cuttings, in terms of decorativeness, not only are not inferior to those obtained from cut tubers, but also surpass them by their developmental strength and flowering, vividly show all the signs of the original variety. In addition, cuttings are the best way to increase the multiplication factor, especially for high-value varieties, if there is a small amount of starting material. With one root tuber, with the skills of cuttings, you can get up to 50 copies, while the planting material is rejuvenated.
Preparing for grafting
Good quality tubers are selected for grafting. But if you purchased not very high-quality planting material (for example, with dried, withered root tubers), it is also better to subject it to cuttings. It is useful to first sprinkle such root tubers abundantly with Epin's solution and let them lie down for a while in the light until the buds are clearly visible.
The tubers are disinfected with the Maxim solution. To do this, they are sprayed with a fungicide solution at a concentration of 4 ml per 2 liters of water from all sides and allowed to dry. After that, they are placed in boxes and covered with light soil with the addition of humus and sand, leaving the root collar on the surface. Open-necked tubers produce more cuttings. If the remains of the stems come from under the root tubers, they are pre-divided so that it is convenient to plant in the correct orientation. Slices on tubers are slightly dried and smeared with brilliant green.
At first, boxes with dahlias are kept at a temperature of +20 ... + 25 ° C, with the appearance of young growth, the temperature is reduced to +15 ... + 18 ° C. In case of insufficient natural light, it is necessary to provide for supplementary lighting with phytolamps in order to obtain strong sprouts (at least 3 mm in diameter). After about 3-4 weeks, shoots 6-10 cm long can be taken for cuttings.
For planting cuttings, you need to prepare dive boxes 10 cm high or purchased greenhouse cuttings with transparent lids, into which 6-7 cm of light soil (with the addition of river sand or perlite) is poured, and on top - 2-3 cm of sifted neutralized peat. In order to avoid the development of diseases and rotting of cuttings, the soil is disinfected with biological products. The most convenient drugs in use are Alirin and Gamair: 1 tablet of drugs is dissolved in a small amount of water (300-500 ml), then brought to 10 liters. The soil is moistened with the solution, covered with a lid or foil and wait 2 weeks before planting.
You can plant each stalk individually - for this, for example, it is convenient to use Giffi tablets. They are soaked in boiling water, allowed to swell and cool. One cuttings are planted in each.
A day before grafting, it is useful to sprinkle the seedlings with Epin-Extra, this will reduce stress during grafting. It is better to cut dahlias in the evening, protecting them from the sun's rays. With a sharp knife, the sprouts are cut off with a "heel", a piece of root tuber or root collar, consisting of strongly shortened internodes with dormant buds (of which 2-4 new shoots subsequently develop, which are removed and also used for cuttings). Cuttings from the upper parts of the root tuber adjacent to the root collar can simply be broken out or cut off with a piece of the root collar. But part of the old stem with buds must be left so that the tuber is not devoid of growth points, so the "heels" should not be large.Do not cut many cuttings at once - the sooner they are planted, the better. If there are a lot of cuttings, in order to avoid withering, they should be covered with a piece of non-woven covering material during work.
You can improve root formation with the help of stimulants. Before planting, the cuttings are dusted with Kornevin or dipped in a mixture of aloe juice with talc. Or, 7-10 days after planting, they are sprayed with a solution of Zircon. In any case, an increase in root formation, branching and thickening of the roots is achieved.
If the cuttings were planted not in special cuttings, but in "Jiffy" or cups, they are placed in transparent containers covered with a film (as described, for example, in our article on cuttings of indoor plants), and placed in a bright place, protecting from the direct sun ... Ventilate to avoid condensation. The leaves and stems of the cuttings must remain dry.
An additional incentive for good rooting is the bottom heating, at which the soil temperature does not exceed + 20 + 22 ° C. It can be organized by placing the plantings closer to the batteries, but a more uniform subsoil heating is obtained when the cuttings are installed on an electric heating pad, turned on at a minimum.
The duration of rooting is directly dependent on the timing of cuttings: in January-February it takes 3-4 weeks, and by April it is reduced to 8-12 days. With the use of stimulants in March, rooting begins within a week.
Young plants obtained by cuttings at the end of winter can be cut again. For this, the apical cuttings are cut obliquely with 1-2 pairs of leaves and planted. Removal of the apical growth causes the awakening of the axillary buds and branching of the remaining parts of the stem. These axillary shoots, in turn, can be used for cuttings, and January plants give a total of 5-6 plants.
Rooted cuttings with the development of a good root system must be planted in a 0.5 liter container. On the eve, they begin to prepare for transplantation and are treated with Epin. If the cuttings grow in "Jiffy", it is important not to miss the moment when the first roots begin to appear between the grid cells. The net is cut off, and the rooted plants are planted in cups, and later transferred into half-liter pots. In them, the plants will remain until planting in the ground at the beginning of June (before planting they are hardened and first covered with non-woven covering material against moisture loss).
After grafting, mothers are removed from the soil, divided into parts with 1-2 tubers, a piece of root collar and 1-2 sprouts, and prepared in greenhouses for planting in the ground.
What else needs to be considered
Usually, dahlias grown from cuttings, by the time of digging, lay smaller, but dense root tubers that are well preserved in winter. Overfed plants do not form them well, so you need to observe moderation in dressing. This ability also depends on the characteristics of the variety, some by autumn manage to form only thin, like a washcloth, root tubers. In order not to lose the variety, "control" specimens are not planted in open ground, but transferred into pots with a diameter of 15-17 cm and added dropwise in the garden. In autumn, they try to extend the growing season for them - they huddle before frost, and after digging, they keep it in a cool room for some time to allow the root tubers to ripen. For storage, they are removed to the basement directly in pots.