Detailed Guide to Carnation Cultivation Techniques: Planting Methods and Management Key Points
Dianthus caryophyllus, also known as carnation, belongs to the Caryophyllaceae family, Dianthus genus. Because of its gorgeous flower colors, long vase life of individual flowers, excellent decorative effect, high yield per unit area, suitability for industrial production, transport and storage, and easy preservation, it is the cut flower with the largest cultivation area and @#@136@#@ value in the world. At present, in addition to Italy, the Netherlands, France and the United States, countries such as Colombia, Kenya and Israel have also become important carnation-producing countries. In China, Shanghai, Yunnan and other places have also planted them in large quantities, supplying domestic and international markets.
(I) Morphological Characteristics and Varieties
Perennial, plant height about 50 cm. Both stems and leaves are covered with a white bloom, resembling Dianthus chinensis. Usually flowers are solitary or in clusters of 2-3, in colors such as red, purple, white, yellow and striped. Flower forms include semi-double, double and wavy. The five petals have notches, the calyx is cylindrical, and the tip is five-cleft.
The main strain groups of carnation are divided by origin into American carnation and Mediterranean carnation (also called European carnation). American carnation has strong adaptability, vigorous growth, longer internodes and wider leaves, but poor cold tolerance, making it suitable for greenhouse cultivation. Mediterranean carnation originated in Italy, France and other places; its plants have shorter internodes, narrow and long leaves, and a calyx that does not split, and it is relatively tolerant of low temperatures and can be cultivated in the open field. It also has rich colors. In recent years, by crossing American carnation and Mediterranean carnation, some varieties have been bred with strong growth vigor, brilliant flower colors, sturdy stems, low-temperature tolerance and high yield.
(II) Biological Characteristics
Carnation is not cold-tolerant or is semi-cold-tolerant; it prefers cool conditions and cannot tolerate heat. The suitable temperature for growth is 20C during the day and 10C-15C at night. When the daytime temperature is above 25C or the nighttime temperature is below 5C, growth vigor weakens. It is suitable for planting in areas with cool summers, warm winters and relatively low humidity. It likes an environment with sufficient light and good ventilation and soil rich in humus with good drainage, pH 6.5-pH 7.5. It fears waterlogging and avoids continuous cropping.
(III) Propagation Methods
Cutting propagation is the main method. Because carnation is extremely susceptible to viral diseases and degenerates after 2-3 years, tissue culture should be used for shoot-tip virus-free culture. In Italy, there are specialized companies producing virus-free carnation seedlings and virus-free cuttings, with products sold domestically and abroad. If new varieties or mother plants are introduced from abroad, a dedicated sterile isolation area should be set up, and first-generation seedlings should be collected as cuttings. Except for July-August, when the temperature is relatively high and unsuitable, cuttings can be taken in all four seasons; the best propagation time is January-March. The mother plants selected for cuttings should have a good root system, grow robustly and be free of pests and diseases. Lateral buds growing from the second and third nodes in the middle of the branch are best, with a length of 10 cm-12 cm. Flower buds on upper lateral buds have already differentiated, and plants propagated from them flower when still very short, causing quality to decline. Before cutting, disinfect the cuttings with a 1000-fold solution of thiophanate-methyl or chlorothalonil. If rooting powder can be used for treatment, the rooting rate can be increased. Treatment with naphthaleneacetic acid or indolebutyric acid also works very well. Perlite or rice-hull ash is best as the cutting bed substrate. Before cutting, water the substrate thoroughly and keep it moist. The planting spacing for cuttings is 1.5 cm-2 cm, and the insertion depth is about 1 cm.
There are two management methods: one is strict shading until rooting; the other is full-light seedling raising, which gives better results. For winter cuttings, the cutting bed should be heated with electric heating wire so that the substrate remains at about 20C. In hot seasons, shade, ventilate and exchange air, and spray water in small amounts but frequently to prevent root rot. Cuttings root in about 10 days and emerge in 20-25 days. If taken out of the bed too early, the roots are very fine and survival is difficult; if too late, the roots intertwine and are easily damaged. After leaving the bed, they should be temporarily planted and hardened off for 1-3 months to restore growth.
(IV) Cultivation Management
1. Open-field cultivation usually involves planting seedlings in autumn and harvesting flowers in the summer of the following year after overwintering. Apply sufficient organic fertilizer when planting. In summer, to prevent heavy rain, a plastic shed can be set up as a roof, but the surroundings should not be enclosed, to facilitate ventilation. When cultivated as a biennial, at the end of October the plants can be cut off near the ground at the first obviously elongated internode and overwintered in the open field. When the temperature is above 0C, no covering is needed, but in East China covering for insulation is generally required. In the following spring, new branches sprout and continue to flower. To reduce disease and maintain soil fertility, rotate with other flowers. Disinfect the soil once every 3-4 years.
2. For cultivation in large sheds and greenhouses, the planting time depends on the market. Generally, if planted in September-October, the flower harvesting time is April-May; if planted in May-June, the flower harvesting time is winter and the Spring Festival. The soil should be moist before planting. Because carnation is a shallow-rooted flower, never plant it too deep; it is enough to cover the roots so it does not fall over. After planting, water thoroughly the first time. Planting density varies with cultivation conditions and variety. For annual cultivation, the row spacing is 17 cm x 20 cm or 15 cm x 17 cm; for biennial cultivation, it is 20 cm x 25 cm or 17 cm x 20 cm.
After the plants grow taller, a net grid should be set up to fix them so they grow upright. Generally, the first layer of netting is about 10 cm above the ground. Later, as the plants grow taller, add a second and third layer of netting, with 20 cm-25 cm between layers. The mesh density of each layer is also not exactly the same.
Two to four weeks after planting, pinching should begin. It is then carried out successively and used to control the flowering period. For example, to make them bloom from December to January of the following year, stop pinching at the end of July. After pinching, gradually raise the temperature to stimulate new buds to sprout. After pinching small seedlings, apply diluted liquid fertilizer once every 10 days. The fertilizer concentration must not be too high, otherwise salts accumulate in the surface soil, causing physiological drought in carnations, with symptoms such as stopped growth, curled leaves, no new root growth and severe yellowing of lower leaves.
The length of light exposure can control the flowering period of carnations. For carnations planted in September north of the Yangtze River, when the plants grow to 5-6 pairs of leaves in winter, give artificial light for 1 month and at the same time raise the temperature, and they can bloom in May of the following year. If artificial light is not given, they will not bloom until June. For artificial lighting in greenhouses and large sheds, generally use one 100-watt bulb per 13 sq m, placed 1 m above the plants, and illuminate for about 3 hours.
In temperature management, from July to September the temperature in greenhouses or large sheds is too high, so pay attention to ventilation and cooling. After mid-October, when the nighttime temperature is below 10C, pay attention to insulation. From early November, keep them closed at night and ventilate only at noon during the day. If conditions permit, begin heating so that the nighttime temperature remains at 13C-15C. In this way, the first peak bloom can be from mid-to-late December to early January, and the second peak bloom from mid-March to early April. This is exactly the off-season for cut flowers, giving the best benefits.
Because carnation has a long cultivation period and large growth volume, it needs continuous topdressing, on average 1-2 times per month, alternating solid fertilizer and liquid fertilizer. This is especially true in September-October and March-April, when growth is vigorous and a large amount of nutrients is needed. If the soil surface becomes compacted, shallow hoeing can be combined with fertilization to promote root growth.
During growth, lateral buds that appear again on flowering branches should be removed as early as possible; those of good quality can be used for cuttings. When several flower buds appear at the stem tip, keep the large central one and remove the others early so that nutrients are concentrated in the central bud.
Carnation often shows calyx splitting, which is related to the heredity of the variety and changes in temperature difference. If the day-night temperature difference exceeds 10C, or the indoor temperature fluctuates too much, calyx splitting can be caused. To prevent calyx splitting, first choose varieties that do not split their calyx, and second control the day-night temperature difference so it is not too large.
Harvest and Storage
Flowers should be harvested in the afternoon, when the first petal has just slightly emerged. After harvesting, sort them, remove substandard ones, grade the good ones and package them, and they can go on the market the next morning. For those not sold temporarily, first let them absorb enough water, then store them in a cold room at 3C-5C. However, note that they must not be placed together with vegetables, fruits, roses, tulips or stock.
Preservation is an important measure for regulating the market and achieving year-round supply. Carnations have the characteristic of concentrated flowering, blooming in large quantities in seasons with suitable temperatures, while producing very few flowers in winter and midsummer. Foreign countries also commonly use cold storage to store fresh flowers. The commonly used methods are wet storage and dry storage. The former is to insert bunches of flower branches into water or preservation solution, with the temperature controlled at 1C-4C and relative humidity at 90%-95%; this method can store them for 5-30 days. The latter is to harvest when the flower buds have not yet opened, package them in polyethylene film bags or boxes, precool them in a cold room and then transfer them to a storage cold room (0C-1C); this method can store them for 4-6 months.