How to grow Phalaenopsis? A detailed guide to protected cultivation techniques

Phalaenopsis has a well-developed root system, a thick and short stem, and is mostly evergreen. Its flowering period is long; a single flower can stay open for 2-4 weeks, and a single spike can bloom for several months. Flower colors include white, white with a red lip, and pink. It has long been known as the "Queen of Orchids". Now let's join the editor of Huinong Network to learn about the protected cultivation techniques for Phalaenopsis orchids.

1. Phalaenopsis cultivation techniques

1. Temperature

In the wild, Phalaenopsis grows at daytime temperatures of 27-32°C and nighttime temperatures of 18-25°C, and prefers high relative humidity and heavy shade. The ambient temperature should not be lower than 15°C or higher than 32°C. The suitable growing temperature is 25-30°C. During the low-temperature flower-forcing stage, the temperature is maintained at 16-22°C, and during the flowering completion stage the temperature is maintained at 18-22°C. After 6 weeks of flower forcing, the temperature can be increased slightly, but if the treatment temperature is too high or the light level is insufficient, the flower spike will elongate, the number of branches will decrease, and the number of flowers will also decrease.

2. Light

Light is the key to growing Phalaenopsis well. During the growth period, there must be enough light to promote the development of leaves and roots. However, too much light can also cause leaf scorch, while insufficient light leads to poor plant growth, sparse leaf distribution, poor flower spike development, and inadequate root development. The best way to use shade netting is a double-layer movable net. One layer of net provides 70% shading, and the other layer provides 50% shading. On bright sunny days or at midday, use the movable nets to avoid extreme sunlight, and never allow direct strong light. In winter, generally 30%-50% shading is required.

Recommended light levels are listed as follows: (1) Red-flowered varieties: ① Growth period: seedling stage 3000-6000 Lux; intermediate seedling stage 6000-12000 Lux; large seedling stage 10000-20000 Lux; ② Low-temperature flower forcing: 15000-20000 Lux; ③ Flowering completion: 20000-25000 Lux. (2) White-flowered varieties: ① Growth period: seedling stage 4000-8000 Lux; intermediate seedling stage 8000-15000 Lux; large seedling stage 15000-25000 Lux; ② Low-temperature flower forcing: 20000-25000 Lux; ③ Flowering completion: 20000-30000 Lux. (3) Small- and medium-flowered varieties: ① Growth period: seedling stage 3000-5000 Lux; intermediate seedling stage 5000-10000 Lux; large seedling stage 10000-15000 Lux; ② Low-temperature flower forcing: 10000-15000 Lux; ③ Flowering completion: 15000-20000 Lux.

In areas where sunlight distribution is relatively even (where light levels are less affected by the seasons), and where the light can be diffused, the light level can be increased by 20%; but at high light levels, relatively high humidity must be maintained.

3. Relative humidity. Phalaenopsis growth requires relatively high air humidity. However, in overly wet environments, high temperature and high humidity often accompany disease. The most suitable humidity range is 60%-85% RH. Generally, if it is below 40% RH for a long time, the leaves lose their luster, and if it is above 90% RH, pests and diseases will increase. Applicable equipment systems include high-pressure misting equipment above the greenhouse to increase mist droplets, watering below the pots, and the use of water walls and fans. However, avoid making the plants wet. When plants grow in a high-humidity environment, daytime temperature and light levels can both be increased, keeping the greenhouse interior at a constant temperature, and good air circulation must be maintained. Therefore, the greenhouse height should preferably be 0.66-1 m above the plants.

4. Fertilizer and water. The growth needs of orchid seedlings differ at each stage, and the fertilizer elements they require also differ. Like all flowering plants, the fertilizer composition changes with the growth stage; seedlings mainly need nitrogen fertilizer, while large seedlings mainly need phosphorus and potassium fertilizer. For fertilizing Phalaenopsis, NPK compound fertilizer can be used. Fertilizer application varies by variety. The pH range is 5.5-6.5, and the EC range is 0.4-1.2 mS/cm. If nitrogen fertilizer is too high, it will cause excessive leaf growth. If the EC value is too high, the roots will die. Generally apply once every 7-10 days, and water once or twice a month to wash away excess salts. Watering should be done only until moist, and prolonged wetness should be avoided. When watering in winter, the water temperature should be adjusted to 18-22°C to avoid damaging the root system from cold.

Phalaenopsis is planted in sphagnum moss and is usually irrigated from the top. The irrigation water must not be polluted, and the sodium and chloride ion concentrations in the water must not exceed 100 mg/L. Bicarbonate concentration must not be excessive. If the water source quality is poor, reverse osmosis treated water must be used.

5. Air. The growing environment for Phalaenopsis requires fresh, circulating air. A stuffy, closed environment is unfavorable for growth. In particular, in winter, if the air inside the greenhouse becomes polluted, it can lead to large-scale bud drop and flower wilting. Generally, small fans are used during cultivation to circulate the air indoors, and ventilation should be frequent.

2. Management of Phalaenopsis at each cultivation stage

1. Small seedlings

Seedlings just removed from the flask up to 15 cm are small seedlings. At this stage the seedlings are relatively fragile and sensitive to the environment. Their suitable growth temperature is between 22-33°C, humidity 60%-85%, and light 3000-8000 Lux, depending on the condition of the seedlings. Because high temperature and high humidity easily breed pests and diseases, spray fungicides and insecticides 2-3 times a month for prevention. For fertilizer, mainly use Peter's (P) 3-1-1 at 3000-5000 times dilution. Apply 3-5 times per month, and water 2-3 additional times. Each application should not be too heavy, so as to promote root development. In addition, after each repotting, water once with a fungicide and once with a rooting fertilizer, and then apply fertilizer and water normally.

2. Intermediate seedlings

Intermediate seedlings refer to orchid seedlings with a leaf spread of 15-25 cm, usually with 4-5 well-grown leaves. Transplant intermediate seedlings into 12-15 cm soft pots and grow them for 5-6 months. Their suitable growing environment: temperature 20-32°C, humidity 50%-80%, light 8000-15000 Lux. For fertilizer, mainly use P2-2-2, supplemented by P3-1-1 (2000-3000 times dilution). Apply 3-4 times per month, and water once or twice a month to keep the sphagnum moss pH normal (5.5-6.5).

3. Large seedlings

Seedlings from 25 cm up to before flower forcing are large seedlings, usually already with more than 5 leaves and robust plants. At this stage, the seedlings should gradually increase their nutrient accumulation to facilitate flower forcing treatment. The suitable environment is: temperature 18-32°C, humidity 50%-80%, light 15000-25000 Lux; their cold resistance and heat resistance are already relatively strong. They can generally tolerate low temperatures of 15-16°C or high temperatures of 35-36°C. But prolonged high temperature will lead to outbreaks of disease. For fertilizer and water, mainly use P1-3-2, supplemented by P2-2-2 at 2000 times dilution, applying 3-4 times per month, and water once or twice a month.

3. Flower forcing treatment

Once Phalaenopsis is sufficiently mature, it can be treated for flowering. This is shown by thick, firm pseudobulbs and 4-5 leaves. Flower forcing is generally carried out 4-4.5 months before the expected flowering time. At this stage, the environment is controlled at a temperature of 16-28°C, humidity 50%-80%, and light 25000-35000 Lux. Within an appropriate range, the larger the seedling, the stronger the light. There should be a temperature difference of at least 10°C. In addition, daytime temperature must not be too high; when it exceeds 30°C, it will block flower spike formation (except for certain varieties). For fertilizer, apply P1-3-2 and P9-45-15 alternately at 1000-2000 times dilution, and continue watering once or twice a month as usual, but pay attention to the root system to avoid root rot. When the flower spike emerges 2-5 cm, management enters the spike-emergence seedling stage.

4. Management of spike-emergence seedlings and flowering plants

The environmental control for seedlings at this stage is the same as for flower forcing treatment, but for fertilizer application, mainly use P1-3-2 at 2000 times dilution. During flowering, fertilizer application should be appropriately reduced. Applying 2-3 times per month is sufficient, and water more. After the flowers fade, keep the temperature at 18-30°C. Preferably above 20°C. Light 20000-25000 Lux, and apply P2-2-2 2-3 times to restore nutrition and help it bloom again.

5. Pest and disease control of Phalaenopsis

Pest and disease control for Phalaenopsis should focus on prevention. A suitable growing environment is the key to reducing the disease rate of orchid seedlings. To prevent pests and diseases, first make the seedlings robust and enhance their own resistance; on the other hand, keep the environment clean and hygienic, ventilate appropriately, and develop good horticultural operating habits. Avoid drastic fluctuations in the growing environment, which cause discomfort to the seedlings and lead to disease. At the same time, once pests or diseases are found causing damage, control them as early as possible.

1. Insect pests

Mainly include scale insects, mites, aphids, nematodes, and whiteflies.

2. Diseases

The most important diseases of orchids are caused by fungi. Symptoms include: rot, rust, damping-off, wilt, canker, anthracnose, scab, spotting, mold, tissue necrosis, and plant decline. There are also other fungal diseases such as southern blight, anthracnose, gray mold, and leaf blight. Bacterial diseases are mainly bacterial soft rot and bacterial brown spot.

A detailed guide to postharvest management of Oncidium

At present, the problems that have emerged in the postharvest handling process of domestic Oncidium growers include low maturity at harvest, short vase life, and flowers interfering with and pulling on each other, causing flower drop during sorting and packing. In addition, because the pollinia cap on the flower spike easily falls off, the flowers age rapidly. The cut end of the flower stem easily rots, especially in hot summer weather. There are also issues with preservation, quarantine, and packaging. If these postharvest handling problems cannot be properly improved and solved, they will inevitably affect quality and reputation and gradually lose existing international market competitiveness. The current domestic postharvest handling operations: the current harvesting and postharvest handling process of domestic Oncidium growers is as follows:

    1. Harvesting: Using various commercially available or homemade scissors or blades, cut from the very base of the flower stem; some growers also twist and pick directly by hand.

    2. Field flower collection: Hold the picked Oncidium in the hand or place it on the plant or growing bed. After a certain number has accumulated, gather them to the very front of the bed or the aisle, then use approximately 20-30 or more cut flowers, wrap the flower portion simply with newspaper, and place them on a cart in a collection bucket already filled with clean water or preservation solution. After the bucket is full, transport it to the grading site for grading work.

    3. Holding: After the flowers are delivered to the grading site, they are usually kept at room temperature until enough quantity has accumulated for grading work. The holding time can exceed 24 hours.

    4. Grading: The currently established Oncidium grading standards are very clear. Oncidium harvested in the field is transported to a production-marketing group or the producer's own grading and handling site for grading, selection, and sorting and packaging. The cut flowers delivered from each production site have their newspaper removed by the grading staff, and then the flowers tangled together are separated one by one, visually selected against the grading standard marks on the workbench, and defective products are removed at the same time.

    5. Packaging: Cut flowers of each grade are made into bunches of 10. The cut end of the flower stem is recut once to reduce infection, and then the stem is tied with different colored tape. Those requiring chemical treatment are isolated for spraying and then dried. After drying, the flower portion is wrapped with transparent plastic paper or a sleeve, and the cut end is fitted with a preservation tube containing preservation and sterilization solution. They are packed 20-50 bunches per box for large packaging or 2-10 bunches per box for small packaging, placed crosswise in the box. After boxing, they are sent directly to refrigerated containers for air transport to Japan, or placed in cold storage to await loading.

    6. Chemical treatment: To comply with foreign customs quarantine, many cut flowers must be chemically treated. Therefore, after grading and tying, they are still placed into collection buckets containing clean water or preservation solution, and then sent to a spraying room for isolated spraying. Only after the chemical agent has dried is final packaging carried out.

    7. Transport: At present, most growers use refrigerated containers delivered to the airport for direct air transport to Japan, to save transport time and ensure the freshness of the cut flowers. A small number of domestic growers also experiment with sea transport to Japan during the peak production period in summer and autumn to reduce freight costs, but the results are not ideal.

    8. Repacking after arrival in Japan: After the products arrive at the Japanese auction market, the flower bunches need to be rearranged again, defective products removed, and flower stems replenished. This operation also increases the probability of damage to the flowers.

    Problems faced in postharvest handling. Looking at the above current domestic Oncidium postharvest operation process, the following problems are faced:

    1. The harvesting action has not been standardized, and the harvesting tools used are not uniform, which easily causes wounds on the plants and flower stems after harvest to suffer disease infection.

    2. Repeated flower collection and separation operations cause tangled flowers to be pulled off, increasing the probability that the pollinia cap is knocked off, and the production rate of ethylene, which ages the flowers, thereby increases.

    3. Manual grading and selection is easily influenced by human factors, causing differences in grading standards and making the quality and grade of cut flowers inconsistent.

    4. Placing boxes horizontally shortens the time for flower stems to absorb the preservation solution in the preservation tube; the preservation period is limited and the cut end of the flower stem easily rots.

    5. The packaging boxes do not have ventilation holes, so during cold storage the temperature inside the box cannot drop quickly to carry away the respiratory heat of the flowers. This accelerates the metabolism of the flowers and makes them age quickly, and may even cause the cut ends of flowers that were not thoroughly disinfected to begin rotting.

    6. Almost all operations are handled manually. In Taiwan, China, where labor is now scarce and wages are high, this kind of labor-intensive handling operation makes it impossible to reduce the production cost of Oncidium, thereby reducing profits.

    7. Based on quarantine requirements, many postharvest flower bunches need chemical treatment, but the application technology has not been established. Some use chemical tanks to directly soak the flower bunches in the chemical solution, while others use high-pressure sprayers with chemical hoses, with the operator holding the nozzle and spraying directly into the flower bunches. Some flower production-marketing groups set up dedicated treatment rooms, place the flower bunches in the room, and use a chemical application mechanism to create a suspended chemical solution for sealed treatment. After the chemical treatment operation, the chemicals are discharged directly to the outside without treatment.

    8. Although cut flowers are immersed in water buckets after harvest, they are not immediately sent to a precooling room for precooling. The timing of precooling cannot be controlled. In the selection and packaging operation area, the temperature is also not maintained at a suitable temperature (12°C).

    9. The internal environment control of cold storage rooms and transport containers at production sites is mainly based only on temperature control, and relative humidity is rarely set or adjusted. Too low relative humidity in the space increases the rate of water loss of cut flowers. The total water loss exceeds the amount of water stored in the preservation tube.

    10. Precooling technology has not been established: which precooling method is best for Oncidium cut flowers has not yet been studied in reports. Precooling methods include forced-air precooling, pressure differential precooling, and vacuum precooling. The efficiency and energy requirements of each precooling method have not yet been fully studied.

    Environmental control problems at handling sites

    Many domestic Oncidium production areas share grading and packaging sites. To reduce indoor temperature, water walls and fans have been installed. This kind of cooling equipment has worked effectively in Phalaenopsis greenhouses. However, when used in Oncidium postharvest handling sites, the following problems have arisen.

    1. In summer in Taiwan, China, using the principle of evaporative cooling for cooling, the ideal situation is to maintain around 27°C. In autumn, it can only reduce room temperature to 20-22°C. The holding temperature for Oncidium postharvest handling is 12°C. Therefore, even if the water wall functions fully, the temperature still cannot reach the temperature required for crop precooling.

    2. The use of water walls and fans has certain construction standards. The distance between the fans and the water wall must be greater than 25 meters for the cooling effect to appear. Few domestic Oncidium collection sites meet this standard. The ventilation volume (number of fans) and water wall area need to be calculated according to engineering guidelines. It should not be arbitrarily constructed based on personal judgment.

    3. Using evaporative cooling for temperature reduction must emphasize airtightness. Personnel entry and exit doors should be set on both sides, opened as sliding doors rather than push-pull doors. Domestic Oncidium handling sites often overlook this requirement. Problems arising from mass production. In the small-scale production stage of Oncidium, because the area is small and the yield is not large, all work can be handled manually. However, when the production area expands and the production period is overly concentrated, a large amount of finished product is concentrated in September-November. A huge quantity of products floods into the collection site, causing too much holding time and making quality prone to deterioration. During mass production, continuing to use traditional operation methods and handling everything manually also causes movements to be too frequent and flower bunches to be easily damaged. Therefore, when the production area expands, decentralized adjustment of the production period is very important. Postharvest handling especially needs to be replanned. Moderate mechanization and rationalization of operation flow lines are necessary conditions for successful industrial production. Large-scale Oncidium cultivation and management is no exception. Improvement and planning of postharvest handling. For the harvesting and postharvest handling operations of specialized Oncidium production areas, improvement and replanning according to their process are as follows:

    1. Site layout: Oncidium production sites within a specialized area should be clustered around a center. Try to make the distance from each production site to the postharvest handling site consistent. Uniformly use the grading, selection, and packaging machinery in the postharvest handling site, and centralize cold storage or container loading and transport. Each production site should be equipped with a simple overhead conveyor to transport harvested cut flowers to the centralized handling site. The centralized handling site should have a precooling collection area, grading and selection area, packing area, cold storage and container loading area, and a container truck platform. The entire area should use refrigerated cooling equipment from air-conditioning machinery as much as possible, so that room temperature is maintained at a more suitable low temperature. In particular, avoid high summer heat causing accelerated aging of Oncidium flowers.

    2. Harvesting: Oncidium harvesting must consider flower stem length and identify maturity, and cannot be completely replaced by machinery, so it still must be mainly manual. Manual operation should have unified standard cutting tools and action procedures, and harvested cut flowers should also avoid tangling with each other. The neatness of the cut end of the flower stem greatly affects the life of the cut flower. Although harvesting with scissors is simple to operate, cutting the flower stem requires strong shearing pressure that compresses and deforms the stem, which easily causes the tissue at the cut end of the stem to die from compression and deformation. As the blade wears over time and the gap increases, the cutting effect becomes worse. The cut tissue is not only compressed but also pulled and torn, unlike the flat and reliable cut produced by a sharp blade through pure cutting. Therefore, harvesting Oncidium should use a sharp tool similar to a scalpel. Harvesting personnel should carry at their waist a small container filled with sterilizing solution, and the cutting knife can be placed in this container for disinfection. Each person should be equipped with at least several cutting knives for rotation.

    3. Transport and grading

    (1) Handling method for large production sites

    A. Transport: Overhead conveyor tracks are set up between each production site and the centralized handling site. The overhead conveyors can be made of plastic to reduce weight and can be easily removed and mounted on the track. Workers can carry multiple overhead conveyors, and when one is full it can be mounted with a new one to continue harvesting, until the conveyors are used up or a single trip's harvesting is finished, then all the conveyors are pulled onto the main track. The overhead conveyor is attached with a pull line and clamps; the pull line is used to pull the overhead conveyor, and the clamps are used to hold Oncidium flower stems. The spacing of the clamps is based on the principle that the flowers of each plant are not easily tangled.

    B. Grading: Oncidium grading standards have been fully established, among which the number of branches and flower stem length of the flower stem are the main grading conditions, and most Oncidium flower stems are distributed in a fan shape, making image processing recognition simple and easy. At present, computer processing speed is fast, and image recognition equipment is cheap and widespread, so machine vision systems should replace manual grading and selection operations. At present, some foreign flower producers install image recognition equipment on self-propelled vehicles, which can be moved to the required location, connected to the track, and then operated directly, suitable for growers with dispersed production sites. Before the cut flowers on the overhead conveyors are sent to the image selection area of the centralized handling site, they are delivered according to the computer grading results into separated packaging compartments on the conveyor belts for each grade.

    (2) Improvement methods for existing production sites

    For improvements to existing production sites, when harvesting manually on site, preliminary grading should be carried out at the same time. Cut flower stems should be hung upside down, held by the clamps on the overhead conveyor. When full, pull the overhead conveyor to the main aisle, then place them separately according to flower bunch length into plastic buckets with preservation solution, and quickly transport them to the handling site for precooling.

    5. Separated packaging: To avoid Oncidium flower bunches being placed together and flowers being easily pulled off during the next handling step due to separation work, which seriously affects quality, for the higher-priced Grade A products, separated packaging compartment boards should be used to ensure quality, so that cut flowers can be packaged and transported individually without mixing with other flower stems and increasing the flower drop rate or pollinia cap fall-off rate. In addition, automatic sleeving equipment can also be used to package flower bunches individually in sleeves for protection.

    6. Preservation treatment: After packaging, the base cut ends of the flower bunches are uniformly recut, and then an improved preservation tube or soft preservation bag is fitted on. Because the old-style preservation tube cannot absorb preservation solution when the flower bunch is placed horizontally in the box, a soft preservation bag developed abroad can be used instead. This kind of soft bag shrinks as the cut flower absorbs water, causing the pressure inside the bag to decrease. In addition, non-woven fabric or sponge can be added inside the preservation tube, so that when the flower stem is placed horizontally, it can still absorb water through the capillary action of the non-woven fabric or sponge.

    7. Boxing, precooling, cold storage, and removal of flower stems: Place the flower stems fitted with preservation tubes or preservation bags and separated packaging upright into large packaging boxes, then seal the boxes. If sleeve packaging is used, they can still be placed horizontally in boxes. The packaging boxes should have an appropriate number and size of ventilation holes to ensure that after the boxes are sealed and sent into the precooling room, the temperature and atmospheric pressure inside the boxes can drop quickly, so as to slow the aging of the flower stems and possible growth of pathogens. After precooling, when sent into refrigerated containers and cold storage rooms, the placement positions of the boxes must allow low-temperature air to blow and flow evenly, without dead corners. After arriving at the sales destination, for flower stems using separated packaging, the box can be placed on its side, and when the bottom of the box is opened, the flower stems can be simply and smoothly pulled out and displayed for sale.

    8. Quarantine and fumigation operations. Whether quarantine and fumigation operations need to be applied depends on whether insects are present in the harvested cut flowers. The insects that need to be dealt with include aphids, Lepidoptera, Coleoptera, and mites. In all fumigation treatment operations, the most reasonable method is to first precool to rapidly lower the temperature, and then carry out reduced-pressure fumigation of the cut flowers. However, domestic technology in this area is not yet mature, and there are still some issues that need to be explored:

    (1) Chemicals used: capable of killing insects, while toxicity is within an allowable range.

    (2) Precooling temperature and precooling time; whether to use normal atmospheric pressure or reduced pressure, and how reduced pressure should be matched during reduced-pressure treatment?

    (3) The corrosion resistance of fumigation equipment.

    (4) In fumigation operations, how should the fumigation chamber be designed, the transport flow lines arranged, and the chemicals applied?

    (5) How can the chemicals be evenly distributed without dead corners, truly achieving an insecticidal effect? How can the shortcomings of traditional soaking or spraying methods be improved?

    (6) After fumigation, how are the chemical agents diluted and discharged into nature?

    Improvement of Oncidium production facilities

    In the postharvest handling process of agricultural products, the more uniform the agricultural product itself and the more consistent its growth traits, the faster and more precise the grading, packaging, and other operations. Domestic Oncidium production sites are mainly shade net houses. In addition to maintaining the internal light level not exceeding the required value, temperature, relative humidity, and air circulation cannot be controlled. Not only can the production period not be adjusted, but pest and disease problems become more serious. How can the facility environment be improved so that Oncidium moves from extensive production to precise production? With relevant environmental control technology already complete, can producers accept the concept of improving the environment, although it increases investment in facilities and equipment, but can disperse the production period and improve quality? Moreover, within facilities with good environmental control, Oncidium pests and diseases are easier to prevent and control. Quarantine fumigation problems are greatly simplified.

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