How much does light affect orchid growth?

Orchidsare shade-tolerant plants, so in generalcultivationmanagement, it is thought that one only needs to plantorchidsin a shaded place, and pay attention to soil, planting material, water, fertilizer and other management. What people fail to realize is that light has an extremely important effect onorchidgrowth, and is the most effective external factor determining vigorous orchid growth and normal development. Light is the energy source for orchids to manufacture nutrients, and also a necessary condition for chlorophyll formation. In orchids, from the formation of chloroplasts, the opening and closing of stomata, the absorption of nutrients and water, the proliferation of cytoplasm, the formation of flower buds, and the manufacture of organic matter, honey production, fragrance release, and other basic physiological processes of life activities and metabolism, everything is affected by light. This is described separately below: 1. Different orchid varieties have different requirements for light conditions, such asCymbidium goeringii、Cymbidium faberiwhich need strong light,Cymbidium ensifolium、Cymbidium sinense、Cymbidium kanranwhich need weaker light; and orchids of the same variety also have different light requirements in different seasons and at different growth stages. For example, in summer and autumn they require dawn light, diffused light, and weak light, and direct sunlight should be avoided to prevent sunscald, and if the temperature is too high, it causes the orchid plants to enter diapause, with little photosynthetic product and insufficient nutrients, a small number of "flower primordia," and failure to form flower buds; on the contrary, if the shade is too dense and the diffused light is too little, the photosynthetic intensity is low, and it also cannot satisfy the formation and development of "flower primordia," both of which will affect flowering; in late autumn, stronger light can be given for 6-8 hours to promote flower bud differentiation and enrich the nutrients for its own growth; in winter when brought indoors, it must be placed in a location with stronger light. 2. Under full shade, orchid leaves are long, dark green, and thin, with sparse flowers, and the flowers have no fragrance when they bloom; under strong light, the leaves are short, withered yellow, and aged, and both the arrow leaves and flower buds may be scorched. With suitable light, the leaves are short and the flowers are many, and the leaves are broad and emerald green; indeed, as Qu Jinze of the Qing Dynasty said in Linghai Lanyan, "Seven parts shaded from the sun, three parts open to the sky, and that is enough." It also says: "With long exposure to the sun, the leaf tips do not scorch." 3. When the flower buds break through the bracts, when the sepals show color, and when the petals open and spread, direct sunlight must be strictly avoided, otherwise the petals are easily scorched or the color turns yellow, and the flowers shrink and do not spread open; if there is no light or insufficient light before flowering, the flower color will not be pretty. 4. Orchids like diffused light and fear direct strong light. Diffused light provides sufficient energy for photosynthesis, allowing organic matter to accumulate and facilitating the formation of "flower primordia." 5. Around the orchid nursery, taller shade trees should be planted, using the period when their leaves are dense and branches are thick to shade the orchids, while when orchids need a relatively large amount of light, it is precisely the time when these trees gradually wither and drop their leaves; the orchid shed must be covered with a shade structure that can be freely adjusted and opened in the morning and evening, so as to adjust the light transmittance needed for orchid growth, creating a place with dawn light in the morning, diffused light at noon, shelter from the west sun in the afternoon, weak light in the evening, rain and dew at night, and at least 2-4 hours of suitable light each day, with light transmittance reaching 40%, so that the orchid'ssprouting rate, flowering rate, and leaf growth and leaf color will all be in a relatively ideal state. Lin Yunjia, Zhang Xiaoru