How to choose orchid potting medium? A detailed method explained clearly in one article
Principles
To grow orchids well, the first issue you encounter is choosing which potting medium to use. To choose a good potting medium, you must understand the growth characteristics of orchids.
People usually describe orchids (specifically Chinese orchids, the same below) as terrestrial plants, but strictly speaking, this is a misunderstanding; orchids should be semi-epiphytic plants. The stomata on orchid leaves are sunken, so respiration is incomplete, and the roots must also help with respiration; orchids mostly grow in places rich in humus with loose soil; orchid growing sites are mostly dry in soil but high in air humidity, and orchid leaves absorb moisture from the air to make up for the shortcomings of orchid roots.
Therefore, when choosing orchid potting medium, we should pay attention to the following principles:
1. Loose and breathable. In the practice of growing orchids, we know to choose granular potting medium and discard powdery potting medium; the reason is to create a loose and breathable environment for orchids, making it easier for orchid roots to breathe.
2. Moisture-retaining without waterlogging. An orchid is a plant and needs moisture; but orchid roots are fleshy roots and cannot tolerate waterlogging. A good potting medium allows water to flow through immediately when watered, never accumulates water, and can still remain moist for a relatively long time.
3. Clean and containing nutrients. Wild orchids have strong resistance, but after transplanting their resistance weakens, there are more pests and diseases, and they also need a certain amount of fertilizer. A clean potting medium containing nutrients is a necessary condition for the normal growth of orchids.
Classification
Above, we described the basic growth characteristics of orchids and the basic principles for choosing potting medium, which opened up our thinking for choosing orchid potting medium.
Orchids are semi-epiphytic plants and, unlike some terrestrial plants, do not have a single unique requirement for potting medium. In particular, people's long-term practical experience in orchid cultivation has proven that the potting media available for us to choose for cultivating orchids are diverse. From the potting media widely used by people and sold on the market, they can be roughly divided into the following three major categories:
1. Soil-type media. Mainly including mountain soil, pond mud, bamboo root soil, peat soil, and various types of humus soil, etc.
This type of potting medium is the main material of traditional growing methods. Its advantages are moisture retention, containing nutrients, easy availability, and low price; its disadvantages are that it easily compacts and accumulates water, does not dry easily after being watered thoroughly, and contains pathogens and easily breeds insects. (The Sichuan Xiantu currently sold on the market and some artificially made granular soil are no longer soil-type media in the traditional sense, and will be discussed later.)
2. Organic-type media. Mainly including bark, decayed wood, coconut coir, wood chips, bagasse, peanut shells, tree fern, palm fiber, and mosses, etc.
The main advantages of this type of potting medium are moisture retention and breathability; after rotting, it can provide organic fertilizer for orchids and is beneficial for orchid root growth. Its disadvantages are that it easily breeds insects and pathogens; especially during the rotting process, it releases heat and harmful substances, which can easily burn orchid roots.
3. Hard potting media. Mainly including pond stone, planting stone, volcanic stone, pumice, perlite, broken brick pieces, and expanded clay pebbles, etc.
The selection of this type of potting medium is the result of continuous exploration and reform by people in the practice of orchid cultivation. Its advantages are that it is granular and not easily broken down, clean and does not breed insects, good in breathability and not prone to compaction, and does not accumulate water; its disadvantages are that it dries easily and contains no nutrients. If the particle size is chosen improperly, it is unfavorable for orchid root growth.
Selection
In summary, the growth characteristics of orchids make it convenient for us to choose orchid potting medium. However, orchids are living things and will live for a long time in the small environment we choose for them; whether they grow well or poorly will be determined by whether we can provide a good environment and management. The choice of potting medium for planting orchids is an important part of the orchid growth environment, so we must never be careless in choosing orchid potting medium. But facing so many orchid potting media, how exactly should we choose?
Historically, although our orchid-growing predecessors used only mountain soil to grow orchids, they also did a lot of exploration. For example, “Soil is the food of orchids; the nature of various soils can be compared to rice. Fuyang soil is like common rice, Yuyao Guanzishan soil is like glutinous rice, Songjiang Beiganshan and Tongzhou Junshan soil are like indica rice...... For those who grow orchids, they must study the looseness and hardness of each soil, mix them evenly, and use them, and then there will be no failure.” With the development of science, modern orchid growers have carried out broader exploration in orchid-growing practice, and the selection of orchid potting medium is even more diverse. The practice of our predecessors and modern orchid growers has proven that as long as it conforms to the growth characteristics of orchids, any kind of potting medium can grow orchids well; the key is that different potting media are suitable for different environments, different pots, and different management. At present, in China's orchid circles, there are three major schools in the selection of main potting media: the traditional soil-type potting medium method mainly in Yunnan, Guizhou, and Sichuan, etc.; the hard potting medium method mainly in Guangdong, Fujian, and Taiwan, China, etc.; and the mixed potting medium method mainly in Jiangsu, Zhejiang, and Shanghai, etc. Below, the potting medium selection and matters needing attention for these three growing methods are discussed separately.
1. Traditional soil-type potting medium growing method.
As the name implies, this growing method is to choose soil-type potting media and adopt traditional cultivation methods to plant orchids. In "Classification" we have already analyzed the advantages and disadvantages of this type of potting medium, so when choosing this type of potting medium to plant orchids, we should pay attention to the following matters:
1. Use granular material as much as possible and sift out the powdery part. The soil must not be too sticky. If it is too sticky, a small amount of coarse sand, wood chips, etc. can be mixed into the soil to improve the soil properties and texture. The planting time must not be too long; after more than one year, the pot must be turned and the soil changed.
2. For pots, choose breathable, open-mouthed clay tile pots or sweating clay pots. A drainage layer must be placed at the bottom of the pot to prevent soil from blocking the drainage holes and causing water accumulation.
3. In daily management, "dry growing" should be the main approach, that is, when watering we should grasp the principle of "do not water if not dry, mainly keep it moist; better dry than too wet." However, we should also pay attention to preventing the "water chestnut shell dryness" phenomenon in which drying starts from the bottom of the pot and moves upward.
4. Because the soil material we choose contains a large amount of humus, there is no need to add base fertilizer. Usually, topdressing can be chosen as the fertilization method. At the same time, pest control and sterilization work must be done well to prevent pests and diseases from attacking orchids.
5. The placement site for orchids should be a well-ventilated area, such as an open or semi-enclosed place like a courtyard or balcony. Usually, the orchid pots can be elevated so that the orchid pots are in an environment with ventilation on all sides, and the air humidity can be relatively lower.
2. Hard potting medium growing method.
Using various hard potting media to plant orchids is a cultivation method that has become popular in China in the last dozen years or so. Compared with the traditional soil-type potting medium growing method, the greatest advantage of this growing method is that it makes our daily management convenient and speeds up the growth rate of orchids. But it also has very obvious defects. Therefore, when choosing this type of potting medium to plant orchids, we must not ignore the following matters:
1. Because this type of potting medium itself is usually granular in varying sizes, when choosing we can generally select large particles like broad beans and small particles like soybeans. Particles that are too large are unfavorable for orchid root growth, while those that are too small are unfavorable for drainage. When planting, if the orchid roots are thicker, more large particles can be placed; if the orchid roots are thinner, more small particles can be placed.
2. In daily management, the "wet growing" method can be used to cultivate orchids, that is, always keep the potting medium moist. However, we should still follow the principle of using different watering methods according to differences in pot material and differences in the strength or weakness of orchid seedlings, and must never overwater.
3. This type of potting medium itself contains no nutrients, and artificial fertilization is needed to ensure the normal growth of orchids. We should pay attention to applying different fertilizers according to different growth stages of orchids. Fertilization can be done by combining topdressing and base fertilizer. For base fertilizer, slow-release granular fertilizer should be chosen; for topdressing, the principle of "dilute, light, frequent" should be followed.
4. This growing method is suitable for environments with relatively high air humidity and gentle breezes. Usually, orchids should be placed in closed or semi-closed places, such as orchid farms, orchid sheds, enclosed balconies, or indoors. Some tree fern fibers or sphagnum moss, etc. can be placed on the pot surface to keep the granules on the pot surface moist.
5. When using it, we can mix a small amount of organic potting media such as bark and coconut coir into this type of potting medium to improve its defect of drying easily, and at the same time it can also provide certain nutrients to orchids.
3. Mixed potting medium growing method.
Because various potting media all have their own defects, using a single potting medium to plant orchids not only requires certain environments and conditions, but also brings inconvenience to our management. The emergence and use of the mixed potting medium growing method can be said to be a great progress in the history of orchid cultivation. This growing method is to mix several potting media from soil-type media, hard potting media, and organic-type media to prepare a new potting medium for planting orchids. Its greatest advantage is that during the preparation process we can increase or decrease the various potting media according to our own environment, pots, and management methods, so as to meet the needs of orchid growth. Likewise, when using this type of potting medium, we need to pay attention to the following matters:
1. Which several potting media we choose in the preparation and in what proportions depends on our own environment and the pots used. We can first choose a few kinds for trial planting. Generally speaking, in an open environment or a well-ventilated semi-enclosed environment, where breathable clay tile pots or sweating clay pots are usually used, more soil-type media and organic-type media can be used, and less hard potting media can be used; if it is a closed or semi-enclosed environment with relatively high air humidity, more hard potting media and organic-type media can be used, and less soil-type media can be used.
2. Because this type of potting medium contains a certain amount of nutrients, usually less or no base fertilizer can be applied, and topdressing should be the main method, following "apply light fertilizer frequently."
3. The soil-type media and organic-type media we choose when preparing this type of potting medium may contain pathogens and pests. Before preparation, drugs or high temperature must be used for sterilization and pest elimination. At the same time, organic-type potting media easily generate heat and harmful substances during the process of rotting and decomposition, so before use, the method of soaking in water and then heating in a microwave oven can be used to solve this.
4. When preparing this type of potting medium, we often use some artificially made granular soil. This type of granular soil indeed has many advantages, but it also has many problems. For example, some use adhesives harmful to orchids, some cannot withstand soaking, some contain saline-alkali components, and some have too much fertilizer...... We should choose them carefully. Through use, the “Hewang” brand Xiantu produced in Sichuan can be the first choice for this type of granular soil, only it needs to be soaked for more than twenty-four hours before use.