Detailed Explanation of the Types of Soilless Cultivation of Flowers and the Key Points of Cultivation Techniques

Soilless cultivation is also called nutrient cultivation. Soilless cultivation of flowers means not using soil, but instead using a nutrient solution made from chemical reagents or chemical fertilizers to supply the nutrients needed for flower growth. It is generally not limited by land conditions, saves water and fertilizer, has fewer pests and diseases, grows robustly and uniformly, with dark green leaves that are numerous and large and brightly colored, and a long flowering period, making it suitable for factory production.

1 Types

Soilless cultivation can be divided into 5 types, namely water culture, sand culture, medium culture, spray culture and nutrient film culture, among which the most commonly used are water culture, sand culture and medium culture.

1.1 Water solution culture

A cultivation method in which the root system of flowers is continuously or intermittently immersed in a nutrient solution. The nutrient solution flows within the cultivation trough to increase the air content. Generally, a nutrient solution depth of 10-15 cm is required. It is suitable for plants with enlarged bulbs such as narcissus and some aquatic plants. In addition, deep flow technique, deep water floating cultivation, floating board capillary hydroponics, dynamic floating root method and floating board hydroponics also belong to water culture methods and are suitable for large-scale production.

1.2 Sand culture

According to the size of the substrate, it is divided into sand culture and gravel culture. Sand culture is a method of cultivating flower plants using sand, perlite, plastic or other inorganic substances with a diameter of less than 0.3 cm as the substrate, plus a nutrient solution. Gravel culture is a method of cultivating flower plants using gravel, basalt, lava, plastic or other substances with a diameter greater than 0.3 cm as the substrate, plus a nutrient solution. Calcareous (limestone) sand and gravel contain a large amount of calcium carbonate, which will cause the pH of the nutrient solution to rise, causing iron to precipitate and affecting plant absorption, so only igneous (volcanic) gravel and sand are suitable as substrate. Irrigate thoroughly with clear water once a week; the culture solution fertilizer is Hyponex; apply at least once a day in summer, and every other day in winter. There are many types of flowers suitable for sand culture, such as geranium, violet, ivy, Lycoris radiata, cyclamen, cacti, and narcissus.

1.3 Medium culture

The medium mainly includes sawdust, straw, cottonseed, etc., with sawdust being the most used. Taking sawdust medium as an example, use medium-coarse sawdust or fine sawdust mixed with an appropriate proportion of shavings. Sawdust from Douglas fir and hemlock is better; some arborvitae sawdust is toxic and cannot be used. After fermentation and decomposition, sawdust is comprehensive in nutrients, rich in nitrogen, phosphorus and potassium, and has a loose texture with moderate dryness and moisture, making it especially suitable for potted asparagus fern, orchids, etc. Placing this potted flower indoors is both clean and hygienic, and elegant and refined, truly an ideal fine ornamental product.

1.4 Spray culture

Spray culture is also called aeroponics. According to whether part of the plant root system is submerged in the nutrient solution layer, it is divided into two types: spray culture and semi-spray culture. That is, all or part of the root system of flower crops is suspended in the air of the cultivation trough, and a spray device is used to atomize the nutrient solution into small droplets that are sprayed directly onto the plant roots to supply the roots with nutrients and water. This can greatly save nutrients and water, and at the same time the oxygen supply to the roots is good, which is beneficial to root development. However, the requirements for spraying are high, and the mist droplets must be fine and uniform. In addition, the root system is greatly affected by external temperature and is difficult to control.

1.5 Nutrient film culture

A hydroponic method in which plants are grown in a shallow layer of nutrient solution. A layer of non-woven fabric can be laid at the bottom of the container, which can both absorb water and allow water to diffuse, while the root system cannot pass through it, and the plants are planted on the non-woven fabric. This enhances and improves the water absorption and aeration conditions of the flowers.

2 Key points of operation techniques

2.1 Pay attention to the acidity and alkalinity of the nutrient solution

The acidity and alkalinity of the nutrient solution directly affect the state, absorption and effectiveness of nutrients, and also affect the growth of flower plants. The required acidity and alkalinity of the nutrient solution for flower growth vary by species. Generally, flowers are more suitable for growing under weakly acidic conditions, with the pH value usually between 5.5 and 6.5. In management, pH test paper can be used to measure the pH value of the nutrient solution. If the pH is too high, an appropriate amount of sulfuric acid solution can be added; if it is too low, sodium hydroxide solution can also be added for correction.

2.2 Pay attention to oxygen absorption

In water culture, flower plants absorb oxygen from the nutrient solution, and the main source of oxygen is brought in by the nutrient solution falling freely from a height, so more irrigation should be done, in small amounts and multiple times. Using porous materials as substrate can reduce the number of irrigations. During the seedling stage, pay attention to the young root system entering the nutrient solution to fully absorb nutrients.

2.3 Pay attention to temperature

Because root temperature plays a great role in the growth and development of flowers, the temperature of the nutrient solution or room temperature should be controlled according to the different requirements of different flowers.

2.4 Pay attention to disinfection

Continuous use of the substrate in soilless cultivation will cause pathogens to breed and accumulate. Therefore, after each planting, the substrate should be disinfected so that it can be reused.

2.4.1 Steam disinfection This can be carried out by directing a steam pipe into the cultivation substrate. For sawdust culture, steam can reach a depth of 80 cm; for a mixed substrate of sand and sawdust at 3:1, steam can penetrate to a depth of 10 cm.

2.4.2 Chemical disinfection For media such as sawdust and straw, formaldehyde is a relatively good fungicide. 1 L of 40% formaldehyde solution can be added to 50 L of water, and applied to the medium at a rate of 20-40 L/sq m, then covered with plastic film for 1 d, which can achieve a disinfecting effect. Before planting, allow the medium to air-dry for about 2 weeks. For sand medium, the cultivation bed can be soaked with 1% bleaching powder for 0.5 h, then rinsed with fresh water to eliminate residual chlorine.