How to choose potting soil? Master these key points

Traditional in our country,cultivation oforchidsmostly uses loose, fine, soft, non-sticky humus soil. This kind of soil is commonly calledorchidmud, which is taken from the soil in the mountainous areas where terrestrial orchids grow abundantly. When digging it up, first remove the surface moss, weeds and the like, then select a thick layer of mud several cun deep, or dig it out from mountain cliffs, rocks and crevices between stones. This kind of mud is small in quantity but excellent in quality. If geographical conditions are limited and such good humus soil cannot be found for the time being, the loose soil of nearby mountain areas, or field soil, or sandy soil mixed with decomposed green manure, oil cake and the like can also be prepared and used. However, saline-alkaline soil and heavily clayey soil must not be used. 1. Humus soil Commonly calledorchidsource or mountain mud. It is weakly acidic, and the mud is loose; brown-black and black colors are superior, while brownish or purplish-red ones are inferior. Regardless of color, loose texture and relatively fast water drainage are best. If the mud is too fine, like powder, after absorbing water it easily causes cracks in the mud layer on the pot surface or gaps between the mud layer along the pot edge and the pot wall (commonly called shelling off); such overly fine mud is not ideal. Of course, no matter which kind of mud it is, only through use can its quality be judged. High-quality orchid mud is not found all over the mountain; the most ideal can be selected from areas whereorchid grassgrows in clumps. After the orchid mud is brought back, first spread it thinly and evenly on the ground, let it dry in the sunlight, and turn and dry it layer by layer for several days to achieve disinfection and sterilization. Then sieve it through a fine sieve, and pick out by hand the scattered tree roots, weeds, small stones and so on floating on the surface of the sieve. The soil that passes through the sieve and the fine-grained mud retained in the sieve are stored separately in indoor jars, and must not be exposed to rain. Because humus soil is rather expensive, it is mainly used forcultivatingfine varieties of orchids. According toCymbidium goeringii, which likes slight moisture, it is suitable to plant with slightly finer mud particles.Cymbidium faberilikes moisture with some dryness, and can be planted with slightly coarser soil. As for other types of orchids, because they require stronger air permeability and have thick, well-developed root systems, coarser mud is harmless. 2. Cow dung soil Pound and grind dried fermented cow dung into fine powder, mix it into sandy soil or field soil, and prepare it in a 1:3 ratio. It is best to choose cow dung from cows fed dry feed in winter, because after the dry grass feed is ruminated, although the fibers are finely broken, they still remain elastic; they are also plant fibers and contain certain nutrients. This kind of cow dung soil is soft and rich in fertilizer, extremely suitable for the orchid roots' aeration-loving habit. 3. Bamboo root mud Soil under bamboo clumps that have grown for many years. The soil contains many half-rotted fine bamboo roots and is weakly acidic. This soil is loose and breathable, with strong drainage and not high fertility, and is very suitable fororchidcultivation. 4. Weathered rock Japan mostly uses weathered rock crushed into different diameters as potting material. The particles at the bottom of the pot are large, and they become smaller toward the top, with the finest on the pot surface. Weathered rock itself has many pores and can absorb part of the water; drainage and aeration between particles are good, so potting orchids is also very successful. 5. Moss Chinese orchids can be potted with moss alone or with some granular crushed brick pieces and the like added. White, dry moss is good; if it is dusty and tea-brown, its quality is poorer. Moss has excellent air permeability and water absorption, so it is beneficial to the growth of roots and buds, but moss itself lacks nutrients, and as use time lengthens its water absorption capacity decreases and its air permeability worsens. Therefore, the amount of watering must be strictly controlled, otherwise root rot is very easily caused. Usually moss must not be used for more than 1 year. If moss can be mixed with charcoal pieces, crushed brick pieces or fern roots, then the potting material need not be replaced every year and can be extended to about two years. Crushed brick pieces and crushed tile pieces are indispensable bottom-of-pot fillers for potting Chinese orchids, and can also be used alone for potting; usually relatively soft red brick is chosen, crushed into particles of different sizes with diameters of 0.3-1.5 cm, and stored separately. During processing, remove the sharp edges and corners of the pieces; crushed brick and crushed tile themselves have many tiny pores and can absorb water. Orchids are plants with strong adaptability; as long as the growing medium does not accumulate water and rot the orchid roots, all kinds of soil with low fertility can sustain them. (Song Shi)