What are the key technical points for orchid care in summer and autumn?
Orchids originate from under the trees in mountain valleys; they are shade-loving and afraid of strong sun. They dislike intense heat and dryness, and require a well-ventilated environment. According to this growth habit, orchid care in summer and autumn must pay attention to four points:
Shading and ventilation. From early summer to the end of September, orchids all need shading, and the shade level must not be less than 70%. When shading, use shade netting for large quantities, and for small quantities place them on a north-facing balcony or under the eaves. During this period, the plants should be spaced out, with no less than 10 cm between pots. It is best to prop the pots up on bricks to increase airflow and allow ventilation and air exchange. In addition, it is necessary to prevent pollution from harmful substances such as sulfur dioxide, hydrogen fluoride and dust, so as to promote healthy growth.
Cooling and humidifying. The suitable growing temperature for orchids is 20°C-28°C. Above 25°C they grow rapidly; above 32°C they are forced into dormancy, with growth at a standstill. When the temperature reaches 30°C, cooling and humidifying measures need to be taken. For those grown outdoors, river sand or plastic film can be spread on the ground; for those grown on balconies, place sponge under the pots and keep it constantly moist.
Spray the plants multiple times a day and sprinkle water on the ground. For indoor growing, an air conditioner or electric fan can be used. Adjust the temperature to below 30°C as much as possible, and keep the air humidity stable above 70%. Watering and fertilizing. At present, most orchid growing uses soil culture, and mostly in pots. The moisture in the potting soil should follow the principle of "moist but not wet, dry but not parched." Watering should be done when the surface soil is slightly white; never overwater, as this causes root rot.
From midsummer to early autumn, generally water thoroughly once in the early morning, and in the evening water as appropriate according to how dry or moist the potting soil is. If the potting soil is found to be dry after noon, replenish water at any time. After mid-autumn, although the climate gradually becomes cooler, the air is dry; following the requirement that "autumn should not be dry," keep the potting soil moist. Fertilizing orchids should follow the principles of small amounts, dilute concentrations, frequent application and timely application, and this is even more necessary in summer and autumn.
From May to September, fertilizer should be applied as appropriate according to different orchid species and different growth stages. For orchid plants in dormancy, or when the temperature is above 30°C, stop fertilizing. Liquid fertilizer is generally applied once every 15-20 days, with a fertilizer-to-water ratio of 1:10; indoors, use solid fertilizer. Large-scale production mostly uses chemical fertilizer at a concentration of about 0.1%. For foliar spraying, prepare the concentration according to the product instructions. Disease prevention and pest control. Orchids are plants prone to many diseases and pests, especially severe in hot and humid seasons. Anthracnose peaks from June to September; carbendazim and thiophanate have good control effects.
For southern blight, drench with a 500-1000 times dilution of chloramphenicol injection, once a day, for two consecutive applications, which can bring the disease under control. Scale insects are a major enemy of orchids; adults can be removed manually, and during the larval hatching period in May-June, spray with pesticide to kill them. For aphids and whiteflies, spray with a 500 times dilution of 10% wettable powder, and two consecutive sprays are enough.
Key points for orchid care in winter
In winter, how to strengthen orchid care is the key to vigorous growth and abundant blooming of orchids the following year. To care for and manage orchids well in winter, different management measures must be taken according to the different varieties and characteristics of orchids. Based on the practical experience of growing orchids over these years, the author believes that to grow and manage orchids well through the winter, the following care and management measures must be taken:1. Bringing them indoors for warmth. Entering winter, the weather gradually turns cold, and especially with frequent cold waves, orchids placed outdoors must be moved indoors promptly to a spot that receives sunlight; if living in a building, it is even better to place the orchid pots on a sunny enclosed balcony. Such an orientation allows sunlight exposure in the morning and evening, which is extremely beneficial for orchid growth, bud formation and blooming. For orchids brought indoors to overwinter, the room temperature should be controlled between 5-15°C. If the room temperature is too low, it cannot provide cold protection and warmth. If too high, it will also affect the dormancy of orchids. However, for winter-flowering Cymbidium kanran and Cymbidium sinense, the room temperature should be kept slightly higher, but must not exceed 15°C. If the room temperature is too high, the flower stems grow slowly and the buds develop poorly, and formed buds are likely to shrink and even die. For the more cold-tolerant Cymbidium goeringii, it needs about 3-4 weeks at around 0°C to complete spring dormancy and vernalization, and only then can Cymbidium goeringii bloom. Therefore, for Cymbidium goeringii overwintering, controlling the room temperature between 3-8°C is most suitable.
2. Controlling watering. "Not dry in summer and autumn, not wet in winter and spring" is the orchid-growing experience summarized by predecessors. In winter, orchids are mostly in a dormant state, with physiological activity almost stopped. At this time they need less water, and the potting soil only needs to be slightly moist for safe overwintering. If the potting soil is indeed very dry, then around noon on a clear, warm day, spray-water with water at the same or similar temperature as the room, just enough to make the potting soil slightly moist; never use large amounts of water, to prevent the potting soil from freezing or becoming too wet and causing root rot. Rain or snow water is best for watering; do not use freshly drawn tap water. If there is no rain or snow water and tap water must be used, let the tap water stand for one or two days until the chlorine has dissipated before watering. When watering, pour from the edge of the pot so that it gradually flows to the roots, until the roots are moist. Do not water the leaves or the orchid crown.
3. Controlling fertilizer and increasing light. Orchids generally do not need fertilizing during winter dormancy. Orchid roots are thick and long with no fibrous roots, and root fungi live symbiotically inside the roots. Generally, when orchids are repotted and the soil is changed every one or two years, the soil contains sufficient nutrients, so no fertilizing at all is needed in winter. However, for Cymbidium goeringii and Cymbidium kanran during the growing period, a small amount of phosphorus-potassium fertilizer can be sprayed on the leaves, such as 1500 times 0.2% potassium dihydrogen phosphate or compound trace elements. In addition, indoors, orchids can be given more light; where light is insufficient, supplemental lighting can be used. If orchids have sufficient light in winter, it is beneficial for vigorous growth and abundant blooming the following year, and can also improve the cold resistance of orchids during overwintering.
4. Timely ventilation and air exchange. Orchids like warmth and also need air circulation, and fear pollution from smoke, dust and foul air. In northern regions, people often burn stoves indoors for heating, and the indoor air often contains smoky, dusty and foul gases. At this time, the orchid pots should be kept away from the stove. At the same time, around noon on clear, warm days, open doors and windows for ventilation and air exchange, or move the pots outdoors to a wind-sheltered, sunny spot to get some sunlight, so the orchid plants can absorb fresh air. For orchids placed on an enclosed balcony, the windows and doors should also be opened to allow air circulation. When the temperature drops, doors and windows should be closed immediately and the pots moved indoors, so the orchid plants do not suffer cold damage.
5. Preventing diseases and pests. For orchids overwintering indoors or on an enclosed balcony, when the temperature and humidity are slightly high, once disease or pest damage is found, spray the appropriate pesticide promptly. Protective spraying should also be done routinely, such as spraying Bordeaux mixture on the potting soil, the orchid plants and the surrounding environment, which can prevent or reduce the occurrence of diseases and pests the following year.
Key points for orchid care in spring
What people usually call spring generally refers to the period from the Beginning of Spring to Grain Rain. In terms of orchid habits, during this time Cymbidium kanran and Cymbidium sinense are in the late flowering stage, Cymbidium goeringii is in full bloom, and Cymbidium faberi is in the early flowering stage, and all kinds of orchids have entered a new growth period. For orchid care in spring, the following points need attention:
Light and temperature. Although orchids are semi-shade plants, the soft sunlight of spring is very beneficial and necessary for orchid growth and development. Whether orchid plants are grown indoors or outdoors, the orchid pots should be moved to a sunny spot as much as possible to receive full sunlight. If the light in the orchid pot area or orchid room is insufficient, supplemental lighting can be used. On clear, warm days, the orchid pots can also be moved outdoors to a wind-sheltered, sunny spot to receive sunlight, which both allows photosynthesis and raises the temperature for the orchid plants. The time must be controlled between 10 a.m. and 4 p.m., and especially do not be careless and leave them outdoors overnight, where they may be hit by frost and cold wind. Variegated-leaf, crystal-art and patterned-leaf types can only receive short periods of light, to prevent leaf variegation from fading. In early spring, the temperature in the orchid shed or orchid room is best kept above 5°C, and for Cymbidium goeringii with buds about to open, 10°C-15°C is suitable. If wind and snow, continuous rain, or a cold wave occurs, doors and windows should be tightly closed to prevent cold wind from invading. If freezing occurs outdoors and the room temperature drops below 5°C, measures should be taken to raise the temperature and keep the room temperature above 0°C. For orchid plants overwintering outdoors or brought out of the room in early spring, double-layer plastic film must be added on rainy and snowy days and at night to avoid frost damage.
Watering and fertilizing. Just entering spring, the temperature is still very low, some varieties are still in dormancy, and water evaporation is slow; the water requirement is very small, so generally water an appropriate amount when the growing medium surface is dry. For Cymbidium goeringii about to bloom and Cymbidium faberi forming buds, watering should be more frequent, but only to the extent that the growing medium is moist. After that, as the temperature gradually rises and new roots and new shoots sprout, the frequency and amount of watering should increase accordingly, but the potting soil must not be too wet, otherwise it easily causes root and shoot rot. When the temperature rises above 20°C or the weather is dry, the orchid plants can be drenched or sprayed with water to maintain moisture, keeping the relative air humidity between 30%-50%. When the temperature is below 15°C in the early period, except for applying phosphorus-potassium fertilizer to Cymbidium goeringii and fertilizing Cymbidium faberi in the middle period to force flowering, other orchid species should not be fertilized. When the temperature is 15°C-20°C, fertilizer can be applied across the board, but the principle of "thin fertilizer applied frequently" must be adhered to, mainly nitrogen fertilizer, with nitrogen, phosphorus and potassium used together, generally once every half month; 0.1% potassium dihydrogen phosphate can also be used for foliar spraying, to promote roots and shoots, cultivate strong plants and enhance disease resistance.
Bringing them outdoors and preventing freezing. The time to bring orchids outdoors should be determined according to local temperatures. Because the temperature difference between southern and northern China is relatively large, the time for bringing them outdoors cannot be generalized; usually the south brings them out first and the north later. The orchid-growing proverb "do not bring them out in spring" is completely consistent with the climate characteristics of the north. The specific time should be controlled between Qingming and Grain Rain, or when the temperature stabilizes above 20°C. Bringing them outdoors too early makes them prone to frost damage, while too late affects growth. One or two days before bringing them outdoors, the doors and windows of the orchid shed or orchid room must be opened for ventilation and air exchange, so they gradually adapt to the outdoor climate environment. However, because spring weather is changeable and temperatures fluctuate greatly, after orchids are brought outdoors, attention must still be paid to cold protection and warmth. Be sure to watch the local weather forecast; in case of a late spring cold snap, continuous rain, flying snow or frost, take frost protection measures promptly, either covering with plastic film or moving them indoors, to avoid serious losses.
Repotting and division. The repotting time for orchids depends on the pot size, number of plants and growth vigor. Generally, large pots with strong seedlings are changed once every 2 years, medium seedlings and diseased or weak seedlings once every 3 years, and tall small pots with strong seedlings once every year. When repotting, take the orchid plant out of the pot, shake off the soil, wash and air-dry the orchid roots, then soak them in a 0.1% potassium permanganate solution for 10-20 minutes to disinfect and sterilize. It is best to also replace the growing medium at the same time and replant in the pot. According to the requirement of dividing spring-flowering types after autumn and summer-autumn-flowering types in spring, while repotting, divide the Cymbidium faberi and Cymbidium ensifolium that should be divided. Before division, withhold water so the potting soil is slightly dry and the root system becomes soft; after lifting the plants, cut off rotten roots and old leaves, and when the roots turn white, cut or pull apart from the wider gap between the pseudobulbs, with each clump preferably having a new shoot or latent bud. For production purposes, they can be divided more, even into single plants; for ornamental purposes, divide 5-6 plants into 1 clump, which makes it easy to sprout and bloom. The cut wounds need to be smeared with plant ash or sulfur powder, and potted after slightly drying. Water from the edge of the pot or use the soaking method to supply water, until the growing medium surface is moist. First place the orchid pot in a shaded spot or one with scattered light, spray water frequently to maintain moisture, and after half a month move it to a sunny place for routine care.
Disease prevention and pest control. Spring weather is warm, a season when pathogens harmful to orchids breed and spread, and also a great time for sterilizing and preventing disease at the orchid-growing site. First, do a good job of cleaning and hygiene at the orchid-growing site, pay attention to ventilation and light transmission, strengthen scientific management, enhance the immunity of orchid plants, and prevent or reduce the occurrence of diseases. Second, use chemicals to disinfect and sterilize. Commonly used fungicides include thiophanate, carbendazim, zineb, lime sulfur mixture, Bordeaux mixture, etc. Choose one or mix two, and spray the front and back of orchid leaves, the pseudobulbs and the growing medium around the roots, generally once every 15-20 days, for 3 consecutive sprays, which can have good results. Once disease occurs, treat according to the disease to control its progression. If certain pest damages are found, use the appropriate pesticide according to the pest and eliminate them promptly and thoroughly.