Research on Soilless Cultivation Techniques for Orchids and a Detailed Explanation of Practical Methods

Soilless cultivation is an advanced cultivation method. Compared with traditional cultivation methods, soilless cultivation can scientifically match the various nutrients required by plants, and it is relatively suitable for cultivating plants in environments without soil or for cultivating more unusual plants. The use of soilless cultivation techniques has provided better conditions for the cultivation of many plants. In recent years, soilless cultivation of orchids has become a trend, and related research and a large number of experiments show that using soilless cultivation techniques to grow orchids helps promote orchid root growth and reduces the degree of pests and diseases in orchid plants, giving it high application value. In the process of soilless cultivation of orchids, growers must also pay attention to the orchids' growth conditions, the selection of cultivation substrate, and precautions for soilless cultivation.

1 Preparation for Soilless Cultivation of Orchids

1.1 Selection of Soilless Cultivation Substrate

Soilless cultivation of orchids requires the use of substrate, and the substrate used can be divided into two types: organic substrate and inorganic substrate. Organic substrates can be divided into soft and hard types. Soft substrates include rice husks, bagasse, charcoal, moss, water grass, sawdust, and spent edible mushroom substrate; hard substrates include tree bark and fern stems and roots. Inorganic substrates include river sand, vermiculite, perlite, volcanic stone, and pumice. When preparing the substrate for orchids, care should be taken to avoid using a single substrate alone, and to choose a combination of organic and inorganic materials as much as possible to ensure sufficient nutrients. When mixing the substrate, attention should be paid to retaining appropriate pores to facilitate orchid root growth.

1.2 Selection of Flower Pots

In addition to considering the cultivation substrate for soilless cultivation, the flower pots used for soilless cultivation are also an aspect that must be noted in preparation for soilless cultivation. A good choice of flower pot can help orchids breathe and drain water, while flower pots with poor air permeability can also affect orchid root growth, thereby causing adverse effects on orchid cultivation quality. For example, porcelain glazed flower pots are highly decorative, but because their water drainage and air permeability are poor, they are not very suitable for soilless cultivation of orchids, so they are often not used; purple clay flower pots have good air permeability and water drainage, but because of their higher cost, they are also not recommended for widespread use; ordinary clay pots or tile pots have good air permeability and water drainage effects and are low in cost, so they can be used when cultivating seedlings. In addition, when choosing orchid pots for soilless cultivation, attention should be paid to the shape of the orchid pot, and tall cylindrical pots should be chosen as much as possible to ensure that the lower part of the orchid pot has drainage and ventilation holes to promote orchid root growth. Newly purchased ceramic pots need to be soaked in water and annealed, and when using old pots, attention should also be paid to disinfection treatment to better ensure the quality of soilless cultivation.

2 Soilless Cultivation Treatment Process

2.1 Orchid Propagation

Orchid propagation can be divided into two methods: sowing and division. Because orchid seeds are small and have a low germination rate, division propagation is still mainly used in current orchid cultivation. Due to the growth habits of orchids, division propagation of orchids is mostly carried out in spring and autumn. The time for division can be chosen according to the orchid's flowering time. Generally, orchids that bloom in early spring can be divided in late autumn, and orchids that bloom in summer can be divided in early spring. When propagating orchids by division, the root system can be cut into several clumps with a knife, and attention should be paid to using scissors to prune the root system and clumps, removing withered roots and rotten roots. For some plants whose roots are shriveled, clean water should be used to soak them until they have absorbed enough water before proceeding. The initially treated orchid seedlings need to be soaked in a diluted broad-spectrum insecticide solution to prevent pests and diseases. After the orchid seedling roots have been pruned and fungi and bacteria have been eliminated, they can be rinsed slightly and, after drying, potted for cultivation.

2.2 Management of Water and Fertilizer

The control and management of water and fertilizer in soilless cultivation of orchids is an important part of ensuring orchid quality. Generally speaking, orchids selected for soilless cultivation have thicker plants, and under soilless conditions water retention is poorer, so special attention must be paid to the frequency of watering orchids. The watering frequency for orchids in soilless cultivation is 3—4 times more than in soil cultivation, and the watering frequency can be adjusted according to differences in season and temperature. For example, in winter and spring, orchids do not grow very vigorously, so watering can be done once in the morning and once in the evening, while in summer and autumn, orchids need a larger amount of water during their growth period, so the watering frequency must be considered according to the actual condition of the cultivation substrate, adhering to the principle of preferring moisture over dryness when watering orchids to ensure sufficient water during the orchid growth period. The fertilizers applied in orchid cultivation are mainly base fertilizer and compound fertilizer. For base fertilizer, decomposed organic fertilizer can be used. Plant ash water, rice washing water, and green grass juice can all provide relatively good fertilizer conditions for orchid growth. Several issues that need attention when fertilizing orchids in soilless cultivation are that fertilizing is not suitable when the temperature is too high or too low, the concentration of fertilizer should be light and strong fertilizer should not be applied, and after each fertilization attention should be paid to watering thoroughly to ensure that the fertilizer can be evenly absorbed by the orchids. In addition, when applying compound fertilizer, attention should be paid to reasonably watering and applying nitrogen, phosphorus, and potassium fertilizers after they are dissolved in water.

2.3 Prevention and Control of Pests and Diseases

The prevention and control of pests and diseases in orchids is of great significance to their growth and development. Although pests and diseases are relatively reduced under soilless cultivation conditions, corresponding pest and disease prevention and control work should still be done well. Common orchid pests and diseases include rot disease, orchid anthracnose, and scale insects. The occurrence of different pests and diseases has certain triggers, and doing a good job in pest and disease prevention and reasonably controlling the triggers can better ensure orchid growth. For example, the occurrence of rot disease has a certain relationship with high temperatures. Under high-temperature conditions, carbendazim and streptomycin can be sprayed to prevent rot disease; the occurrence of anthracnose also usually occurs under high-temperature conditions. After the disease occurs, potassium permanganate solution can be used to treat its leaves to avoid worsening of the condition.

2.4 Preparation for Orchids Overwintering

There are many orchid varieties, and the cold tolerance of different orchids is not exactly the same. In the process of soilless cultivation of orchids, growers need to pay attention to considering different cultivation methods according to the orchids' properties. In the process of soilless cultivation, orchids are classified according to their cold tolerance. When preparing for overwintering, non-cold-tolerant varieties that are susceptible to freezing damage are sent to greenhouses for cultivation, while relatively cold-tolerant varieties are cultivated under suitable indoor conditions according to their growth temperature. Overwintering preparation must be done well according to the orchid variety as well as the solar terms and temperature, to avoid freezing damage during orchid cultivation.

3 Conclusion

Soilless cultivation of orchids provides better conditions for orchid growth. High-quality soilless cultivation helps orchids grow vigorously and, to a certain extent, avoids the occurrence of pests and diseases. In the process of soilless cultivation of orchids, choosing high-quality cultivation substrate, setting up the environment according to the orchids' living habits, and doing a good job in pest and disease prevention can all improve the success rate of soilless cultivation and the quality of flower cultivation. Strengthening the control and management of each link in soilless cultivation of orchids helps increase the orchid sprouting rate and flowering rate, and can better ensure orchid cultivation quality.