A Detailed Guide to the Light Requirements and Regulation Methods of Chinese Orchids

　　Orchids' photosynthesis mainly involves their roots drawing nutrients and water from the growing medium, their leaves absorbing carbon dioxide from the air, and their chlorophyll absorbing sunlight (light energy) to synthesize carbohydrates within the plant body, that is, converting light energy into chemical energy and releasing oxygen. This continuous cycle enablesorchidsto develop and grow, produce new plants while old plants age and die, metabolize, and cycle endlessly, allowing life to continue and the species to reproduce. Therefore, light is extremely important fororchidgrowth. Orchids love sunlight but avoid scorching exposure Orchids are semi-shade plants; they love sunlight but avoid scorching exposure. Long hours of exposure are also unfavorable to orchids, because orchids have a saturation point for light requirements, and from people's practical experience it is known that this is also flexible. Ou Jince of the Qing Dynasty, in his book "Linghai Lanyan" (Talks on Orchids from the Lingnan Region), already pointed out that "in the method ofgrowing orchids, more sun makes better flowers, more shade makes better leaves" and "reckoned in tenths, seven parts shade and three parts open sky is sufficient!" He also said: "...the standard is that the leaf tips are not scorched after prolonged sunning; this is the unchanging method handed down by our forebears." Recently some experimenters believe that a shade level of 60% in the orchid shed and 4 hours of light per day are enough, because after light reaches the saturation point, even better sunlight has no effect on orchids. But others believe that after photosynthesis is carried out, weak light is still needed as a supplement. The intensity of light required is also closely related to the chlorophyll of the orchid plant; the more chlorophyll, the stronger the photosynthesis. The first step of photosynthesis is how to promote chlorophyll production, and the formation of chlorophyll can be aided by applying more nitrogen fertilizer and supplying trace elements that promote chlorophyll formation, such as magnesium, manganese, and iron. Once chlorophyll is formed, it can promote the reproduction of the plant body. In short, the stronger the light, the more fertilizer and water are needed; if ventilation is better, it is even more favorable to the plant's respiration and photosynthesis, making the orchid grow faster. Outdoor orchid growing must be shaded Measured with precision light-measuring instruments, after shading the outdoor orchid shed, well-growing orchidflowershave a light intensity of 5000-10000 Lux (lux, that is, "meter-candle"), and their sprouting rate, flowering rate, leaves and leaf color are all excellent. At present, black plastic shade netting (commonly called black net) can be used for shading, with specifications of 45%-50%, 70%-75%, 90% shade and other different models, and one to two layers can be used to control the required shade level. The light for growing orchids outdoors and on balconies is affected by sunny and rainy days, seasons, and changes from morning to noon to evening, with enormous variation, and cannot compare with the easily controlled light indoors. Red and blue light tubes control light It is known that: plants absorb red light most strongly, blue light next, and both are useful for photosynthesis. Red light can promote the growth of orchidflowers, while blue light is indispensable for thickening stems and leaves, accelerating plant development, and regulating stomatal opening. Violet light and ultraviolet light mainly form anthocyanins and inhibit the elongation of branches and leaves; too strong ultraviolet light will scorch orchid leaves, so short-wave tubes of ultraviolet light are not yet suitable for use. For indoorcultivation, a mixed light of red, blue, and white light tubes can be used to control lighting, and the pink-purple plant light tubes sold in aquarium shops can also be used. Experiments prove:cultivatingBaosui orchids, a light intensity of 5000 lux can be used; for variegated Baosui orchids, 4000 lux; for narrow fine-leavedFour Seasonsorchids, autumn Hui,Spring orchidsand others that need slightly more light, a light intensity of 10000 lux can be used. Currently, 40-watt pure red light tubes (main wavelength 642 nanometers), pure blue light tubes (main wavelength 472 nanometers), and ordinary daylight tubes are combined so that 929 sq cm (1 square foot) maintains 20 watts of light, because light intensity is inversely proportional to the square of the distance from the light source to the leaf surface, that is, the closer the distance, the stronger the light, so the height of the light tubes can be adjusted to control the distance. Baosui orchids can be placed 15-25 cm from the light tubes; variegated Baosui orchids at 25-30 cm; narrow fine-leaved orchids at 10-12 cm. SomeFour Seasonsorchidscultivatedat a distance of 2 cm from the light tubes also showed no scorching of orchid leaves, and the effect was also good, which shows that the light requirements of orchids are also flexible.