Environmental factors of orchids: fertilizer

The roots of orchids are generally symbiotic with fungi, which is called mycorrhiza. The fungus penetrated into the root of the orchid, and finally its own tissue was absorbed by the root of the orchid as nourishment. But in any case, the nutrients provided by fungi are insufficient. In other words, orchids can not be fed entirely by fungi, but still need to be fertilized. In the natural state, orchids are mostly born in the environment of loose matrix (soil, sand, humus, etc.) and good drainage, and epiphytic orchids are attached to rock walls or tree trunks with slightly accumulated soil or accumulation of humus. They don't get too much fertilizer, and they don't need too much fertilizer. Too much fertilizer can harm orchids and even cause death. This is also said in the experience of planting orchids in ancient China. For example, in "Zhi Lan Shuo" at the end of the Tang Dynasty, Yang Kui believed that if he followed the example of vegetable farmers, that is, if they were watered with human feces and urine, it would be inevitable that "the seedlings would suddenly conceive and the roots would rot." Huang Tingjian also has the phrase "Wo to Tang Ming is Fang". It all means that orchids should not be fertilized, otherwise it will cause death. This is obviously due to the poor excretion of toxic salts concentrated on the substrate. Foreign early orchid cultivation manuals also believe that it is OK to add some bone powder, clay cells, blood powder and humus at will. However, modern studies have shown that rational fertilization is very necessary to promote the growth of orchids, especially in commercial production or large-scale cultivation.

Orchid fertilizer can be divided into organic fertilizer and inorganic fertilizer. Organic fertilizer includes cow (horse, sheep) dung, bone meal, blood meal, meal (soybean cake, rapeseed cake, cottonseed cake, tea seed cake, etc.), humus and so on. Inorganic fertilizer is chemical fertilizer, mainly nitrogen fertilizer (sulfuric acid hinge, nitrate hinge, hydrogen carbonate hinge, chloride lock, urea, etc.), phosphate fertilizer (calcium superphosphate, potassium hydrogen phosphate, potassium dihydrogen phosphate, etc.) and potassium fertilizer (potassium sulfate, potassium chloride, potassium hydrogen phosphate, etc.). In addition, trace amounts of iron (Fe), manganese (Mn), magnesium (Mg), calcium (Ca), copper (Cu), diamond (Co), boron (B), zinc (Zn), Mo and so on are needed.

The use of orchid fertilizer should be very careful so as not to damage the roots and cause death. Organic fertilizer can not be used until it is fermented for 2 to 3 months. The dilution multiple can be diluted by adding 20: 30 times water or more according to organic fertilizer. Take cow dung as an example, dilute it to a light yellow and remove the residue after clarification. Chemical fertilizers are generally diluted 1000-10000 times, that is, 0.01%-0.1%. For seedlings, the ratio of nitrogen, phosphorus and potassium (refers to the actual ratio of nitrogen, phosphorus and potassium) is generally 3:1:1, while for growing plants it is 1:1:1. If promote better flowering, it is 1:3:1, plus the right amount of trace elements. In many visits to some orchid plantations in Japan, Europe and the United States, the author learned that they generally do not advocate the use of base fertilizer for fear of poor control of the amount of fertilizer, resulting in the accumulation of toxic salt, thus harming the roots. And advocate the use of diluted liquid fertilizer, with a fine hole sprinkler on the leaf, would rather dilute some, more times, not too thick, the interval is too long. Usually once a day in spring and summer, the dilution multiple can be larger, or alternately with watering, once every 2 to 3 days, the water can wash the retained fertilizer, with less harm and better effect. Do not use lazy methods, that is, once a month, the concentration should be increased 10 times. This is in line with China's old experience, that is, "diligence but light, abstinence and thick". Of course, in view of manpower, time and other difficulties, it can also be appropriately extended to three or four times a week. This depends entirely on the grower to make a decision according to the actual situation, not mechanically using the experience of outsiders. The fertilization season generally begins at the end of spring and stops at the end of autumn, and some species can be earlier. The appropriate fertilization time should be moderate temperature (18-25 ℃), and avoid fertilization above 30 ℃ or below 10 degrees. Fertilizing if the temperature is too high will hurt the orchid itself; if the temperature is too low to absorb it, it will be a waste of fertilizer. (Chen Xinqi, Ji Zhanhe)