Orchids, like crops and other plants, need to be fertilized in moderation to grow strong, bloom and have luxuriant leaves and a strong fragrance. However, excessive fertilization will cause fertilizer damage, which may lead to poor growth or even death of the whole plant. What kind of fertilizer should orchids be fertilized, how to fertilize them, and when to fertilize them? This is a relatively complex technical issue in orchid cultivation and care. Based on my own practice and the experience of orchid friends, I would like to share some of my superficial experience for reference by orchid growers, and I invite orchid experts to correct me.

Fertilizer types and varieties

Fertilizers used for orchids are divided into three categories: organic fertilizers, inorganic fertilizers, and biological bacterial fertilizers. The advantages of organic fertilizers are that they contain nitrogen, phosphorus, and potassium, are sufficient in fertility, have a long fertilizer effect, and can improve the soil; the disadvantages are that they are unhygienic, have a bad smell, are prone to infectious bacteria, and breed pests. The advantages of inorganic fertilizers are that they are widely available, easy to apply, have a fast fertilizer effect, are odorless, and do not carry bacteria; the disadvantages are that they are difficult to master, and long-term application will cause soil compaction and hardening. Biological bacterial fertilizers are made with the latest technology and have a positive effect on the growth and development of orchids.

Organic fertilizer

Organic fertilizer is farmyard manure, which includes human feces and urine; excrement of poultry and livestock such as horses, donkeys, mules, camels, cattle, sheep, deer, pigs, dogs, rabbits, chickens, ducks, geese, etc.; bean cakes, rapeseed cakes, sesame paste residue, peanut bran, fish meal, bone meal, rice bran, wood ash; leftovers from slaughtering poultry and livestock, fish water, rice washing water, fruit peels, vegetable leaves, various residues; humus, minerals and certain elements in culture soil, etc. All organic fertilizers must be fermented, sterilized and deodorized before use. Or use containers such as jars to ferment liquid fertilizer according to a certain fertilizer-water ratio; or use soil and fertilizer piles to make soil fertilizer, or spray water to seal and ferment and then crush into block or powder solid fertilizer. The fermentation time may take several months or 1 to 2 years, with the principle of full fermentation, sterilization, insect-free, tasteless, easy to absorb and high fertilizer efficiency. When using, the original liquid fertilizer must be diluted according to a certain fertilizer-water ratio. Solid fertilizer should also be applied in proportion to the size of the flowerpot and the number of orchids. It is better to use a light fertilizer than a thick one, and a little fertilizer than a lot.

Inorganic fertilizers

Inorganic fertilizers are chemical fertilizers. According to the introduction of Lan Zhu Lankan, the nutrients required by orchids include 16 elements, including carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, iron, manganese, zinc, copper, molybdenum, boron, and chlorine. Among these elements, carbon, hydrogen, and oxygen mostly come from air and water, while calcium, magnesium, sulfur, iron, and other elements are contained in the soil and are generally not lacking. In addition to providing sufficient nitrogen, phosphorus, and potassium, a certain amount of other elements must be supplemented when using artificially prepared culture soil to cultivate orchids. Although the difference in the amount of orchids' requirements for various elements is not very large, they play different roles in the growth and development of plants, and are neither indispensable nor replaceable. Among the many nutrients mentioned above, nitrogen, phosphorus, and potassium are macroelements, often referred to as the "three elements of fertilizer", and the others are trace elements. The role of "nitrogen" is to promote the formation of chlorophyll and protein, deepen the leaf color, enlarge the leaves, and facilitate photosynthesis. Phosphorus can make orchid cells divide, promote root respiration, increase nutrient absorption, participate in photosynthesis, accelerate the movement of photosynthetic products to the roots, promote root development, and facilitate flower bud differentiation and flowering; it can also enhance plant resistance and improve the ability to resist drought, cold, lodging, and pests and diseases. In particular, applying phosphorus fertilizer during the seedling stage can promote the early growth of the root system of young plants. Potassium participates in some metabolic processes and is usually distributed in the most active growth parts such as young buds, tender leaves, and root tips. It can promote photosynthesis, promote the absorption of nitrogen and phosphorus, facilitate the formation of protein, and enhance the plant's ability to resist disasters.

According to the orchid's demand for nutrients, the following fertilizer types can be selected for application: nitrogen-containing ones include urea, ammonium sulfate, and ammonium nitrate; phosphorus-containing ones include calcium superphosphate, potassium dihydrogen phosphate, and potassium nitrate; there are many kinds of compound fertilizers containing nitrogen, phosphorus, and potassium in different proportions; those containing trace elements of calcium, iron, zinc, magnesium, copper, boron, and molybdenum also have corresponding fertilizer products, which are available on the market.

Biological fertilizer

Orchid books and periodicals introduce orchid-specific fertilizers or comprehensive fertilizers made at home and abroad, such as Huabao, Xishuo, Duomu, Shida, Gaole, Gaochanling, Lanjunwang, Jialanbao, Penshibao, Yemianbao, Tianlibao, Feiligao, Yimudan, Cugensheng, Huagenwang, Lufenwei, and Plant Health. If you are interested or need it, you can buy them in the orchid market or agricultural supply market. The nutrient content, use time, application method, and dilution concentration should be handled according to the product instructions.

Fertilization forms and methods

Fertilization form

There are three forms of fertilization: basal fertilizer, root fertilization and foliar fertilization, with root fertilization as the main form and foliar fertilization as the auxiliary form.

base fertilizer

It is to apply organic fertilizer or inorganic fertilizer to the bottom of the pot or mix it into the planting material. If it is not applied properly, it is easy to cause root rot, so it is generally not used. If it is used, organic fertilizer must be fully fermented and decomposed, or block fertilizer should be applied to the bottom of the pot, or powder fertilizer should be mixed into the planting material; inorganic fertilizer is mostly phosphorus fertilizer mixed into the planting material, and it is better to use less rather than more.

Root fertilization

Root fertilization is the most common and basic method of fertilizing orchids. It can be divided into two forms: liquid fertilizer application and solid fertilizer application. (1) Liquid fertilizer. Collected animal excrement, leftovers from slaughtered poultry and livestock, various cakes, dregs, husks and other materials can be used as topdressing for orchids after they have been fermented and decomposed. Before application, first stir the fermented water fertilizer thoroughly to allow it to settle, then take out the clear liquid, filter it with a mesh, and put it into a larger container; then dilute it with 10 to 50 times of clean water according to different fermented materials, fertilizer concentrations, different orchid species, different growth periods and different growth potentials. It is better to be insufficient than excessive; finally, use a ladle or watering can to irrigate from the edge of the pot. If hard planting materials are used, it is also necessary to use the immersion pot method or circulation method, otherwise it will be detrimental to the absorption of orchid roots. The immersion method is to pour the prepared fertilizer liquid into the pot, then put the orchid pot in, let the fertilizer liquid slowly enter the pot through the drainage hole, and make the pot surface moist. The circulation method is to put the orchid pot into a pot, use a ladle or spoon to pour the fertilizer liquid into the pot, and then pour the fertilizer liquid flowing out of the bottom of the pot into the pot, and repeat this process so that the hard planting material absorbs more fertilizer liquid. The fertilizer liquid must be light when fertilizing with these two methods, otherwise it will suffer fertilizer damage.

(2) Solid fertilizer. Dry the fermented fertilizer and process it into blocks or powder as needed. Apply an appropriate amount to the surface of the pot in autumn, winter and rainy season. It will be gradually absorbed by the orchid roots through rainwater or artificial watering. Summer and autumn are hot seasons. If solid fertilizer is applied to the surface of the pot, it is easy to breed insects, emit odor, and pollute the living environment. Therefore, it is not suitable to apply it in hot weather.

(3) Fertilizers. There are two forms: dry application and dilution. Dry application is mostly used for nitrogen, phosphorus and potassium granular compound fertilizers. For a 15-20 cm orchid pot, more than ten granules can be applied at a time, or two granules can be applied per seedling. Generally, it is applied once a month. During the seedling growth period, a little urea can also be applied to promote growth. The concentration of fertilizer dilution varies according to the variety and content. Generally speaking, urea, potassium sulfate, potassium nitrate 0.1%, potassium dihydrogen phosphate 0.2%, superphosphate, magnesium sulfate, ferrous sulfate 0.5%, zinc sulfate, molybdic acid 0.1%, copper sulfate 0.2%, borax, boric acid 0.3%.

(4) Biological fertilizers. The various biological fertilizers introduced in the above books and periodicals must be prepared strictly according to the product instructions. It should also be noted that among these micro-fertilizers, if they are not special fertilizers for orchids but general agricultural fertilizers, their dilution concentration should be even lighter. Because orchids are symbiotic with orchid bacteria and grow more slowly than other plants, they require less fertilizer. If the concentration is prepared according to the original ratio, it is easy to damage the orchid roots.

Foliar fertilization

Also known as foliar fertilization, it is to supplement the deficiency of root fertilization. The fertilizers used are mostly chemical fertilizers, and the dilution concentration is basically the same as that of root fertilization. The focus of foliar fertilization must be on the back of the leaves. The reason is that the front of the leaves is covered with a shiny cuticle, which makes it difficult for fertilizer to enter. The back of the leaves does not have this cuticle, and there are many pores, so fertilizer can easily penetrate and be absorbed. In order to ensure the focus on the back of the leaves, when spraying fertilizer on orchids placed on the ground, the orchid pot should be placed on its side and rotated for a circle to ensure that the fertilizer reaches all sides and promote the balanced growth of the orchids.

Fertilization method

The method of fertilizing orchids mainly considers the following aspects, but in actual operation, it is necessary to make overall arrangements and master them flexibly, rather than being stereotyped or rigidly applied.

1. Apply fertilizer according to the farming season. After orchids enter spring, they recover after a period of time and then start a new round of growth. When the temperature rises to 10 degrees, foliar fertilization can be carried out, which not only promotes the recovery of orchids, but also replenishes the nutrients consumed in winter. After that, foliar fertilization should be carried out regularly or irregularly according to the growth of orchids. At the turn of spring and summer, orchids begin to sprout. At this time, root fertilization can promote the rapid and frequent growth of new buds. Fertilizers are mainly nitrogen, and organic liquid fertilizers can be used, or diluted with chemical fertilizers. In autumn, orchids enter the reproductive growth period, some differentiate flower buds, and some are growing buds. Fertilization should be mainly phosphorus and potassium. In late autumn and early winter, it is advisable to apply winter fertilizers. Solid fertilizers can be applied, and liquid fertilizers with higher concentrations can be applied, which can not only enhance the cold resistance of plants, but also lay a good foundation for the next year. In midsummer and severe winter, most orchids are in a dormant period, so fertilization should be stopped.

2. Apply according to the growth period of orchids. The growth period of orchids is seedling stage, vegetative growth period, reproductive growth period and flowering period. The tasks of each period are different, and the fertilizers required are also different. The seedling stage includes germination, rooting, and leafing. The nutrients needed are mainly nitrogen. 0.1% urea solution can be applied in the pot, or 1:20~50 times organic liquid fertilizer can be applied, but be careful not to splash the fertilizer into the center of the young buds to damage the orchid buds. Full-price fertilizers can be applied during the vegetative growth period, both organic and inorganic fertilizers can be used, and they can be applied alternately to complement each other's advantages. During the reproductive growth period, phosphorus and potassium fertilizers are mainly applied to promote flower bud differentiation, large flowers, and strong fragrance.

3. Fertilization according to orchid varieties Different orchid varieties have different requirements for nutrients. If the same amount of fertilizer is applied, some will be insufficient and some will be excessive. Generally speaking, Chunlan plants have small leaves, narrow roots, and require less fertilizer, so less fertilizer can be applied. Jianlan and Hanlan plants are of medium size and require moderate fertilizer, so normal fertilization is appropriate. Huilan has long, wide leaves, thick and strong roots, and requires more fertilizer, so more fertilizer should be applied. Molan, Tiger Orchid, and Cymbidium Orchid are tall, long, and wide, and require more fertilizer, so more fertilizer should be applied. Line Art, Crystal, Spotted Art Orchid, and weak, new, and unique orchid plants must be fertilized carefully, and less fertilizer should be applied rather than more, and light fertilizer should be applied rather than concentrated fertilizer. If raw fertilizer, concentrated fertilizer, or excessive fertilizer is applied, it will not only be easy to be damaged by fertilizer, but also seriously degrade the art.

4. Fertilize according to the growth of orchids. Due to various reasons, some orchids grow vigorously while others grow weakly. Fertilization must be different for each orchid. It cannot be treated equally. Fertilization should be applied frequently and frequently to strong orchids; fertilization should be applied normally to those with average growth; less fertilizer should be applied to those with poor growth, with a lower concentration and longer intervals. Fertilizer should not be applied to weak orchids, diseased orchids, or those that have just been removed from the mountain or newly potted. After a period of maintenance, weak orchids, removed from the mountain or newly potted plants can be fertilized on the leaves first, and then on the roots.

5. Apply fertilizer according to the hardness of the planting material. Soft planting materials generally contain organic matter and multiple nutrients, so topdressing is not needed. Hard planting materials may contain a single element or no nutrients, so topdressing is the only way to provide nutrients. In addition, soft planting materials are easy to absorb, while hard planting materials flow down while being poured from above, making them difficult to penetrate. So, the immersion method or circulation method must be adopted to apply them in order to be effective.

Other factors such as the size of the orchid pot and the number of orchid plants should also be properly controlled and we should not be egalitarian.

Fertilization time and taboos

1. The specific time for fertilization is: first, it should be sunny, warm, windless and humid, especially in the evening. Second, the soil should be neither dry nor moist. Dry soil can easily damage the orchid roots, while too wet soil is not conducive to the absorption of fertilizer. Third, after watering the fertilizer, spray the fertilizer on the orchid leaves, orchids and bulbs with a sprayer immediately; and water the next morning to drain the excess or residual fertilizer. Fourth, in the case of continuous spring rain and hot summer, the time for fertilization should be chosen wisely. Fertilizer can be applied 2 to 3 days after the rain stops and the weather clears up; in the hot summer, it should be applied when the weather turns cooler.

2. To prevent orchids from suffering from fertilizer damage and affecting their normal growth, in addition to paying attention to applying fertilizers in appropriate amounts and concentrations, there are also requirements to avoid applying fertilizers in extremely hot weather, extremely cold weather, rainy days, at noon, during the flowering period, on diseased plants, on old and weak seedlings, within one year of being brought down from the mountains, before new roots have grown in new pots, and in addition to the "ten things not to do" requirement: no fertilization in these areas: no fertilization in extremely hot weather, no fertilization in severe cold weather, no fertilization on rainy days, no fertilization at noon, no fertilization during the flowering period, no fertilization on diseased plants, no fertilization on old and weak seedlings, no fertilization on orchids that have been brought down from the mountains within one year, no fertilization before new roots have grown in new pots, and no application of raw fertilizers or concentrated fertilizers.

3. Measures to save orchids from fertilizer damage. Some orchid lovers are eager for quick results and do not follow the growth habits of orchids. They arbitrarily increase the amount and concentration of fertilizers and apply fertilizers frequently and suddenly, which has the opposite effect and causes fertilizer damage. Or they are careless and apply raw fertilizers, concentrated fertilizers or excessive fertilizers, which may lead to accidents and misfortunes. If the orchid leaves turn from green to yellow, the orchid plants wilt slightly, and the orchids are listless, these are typical symptoms of fertilizer damage. For mild cases, water them abundantly so that some fertilizers flow out of the pot with the water to reduce the damage. For severe cases, remove the seedlings, wash them, dry them, replace them with new planting materials, repot them, and move them to a place with diffuse light or semi-shade for maintenance. This may save the plant.