Layered Use of Wood Chips and Orchid Soil Granules in Orchid Cultivation

For potting media for Chinese orchids grown in pots, aside from requiring a slightly acidic pH and being free ofpests and diseases, the orchid growing substrate is required to be loose and breathable, with a high water-holding capacity, easy to water thoroughly and drain, containing comprehensive nutrients, and still able to maintain these properties under long-term watering and flushing. In this regard, traditional orchid growing favored mountain soil from beneath the forests of orchid-producing mountains, which has comprehensive nutrients but insufficient aeration, and is also not easy to obtain in non-orchid-producing areas. Overseas growers mostly use several types of granular substrates in combination, but the drawback is insufficient nutrients, requiring frequent application of special liquid fertilizer. Based on the physiological characteristics of orchid roots, the author, adapting to local conditions, used coarse wood chips, mountain soil granules, acidic round soil granules, weathered rock granules, crushed brick granules, peat soil granules, small pieces of rotten wood and tree bark, peanut shells, walnut shells, sphagnum moss, and fermented oil cake, etc., as growing media, and by layering or mixing several of them and then potting the orchids, all achieved relatively good results. The characteristics of this method are: after mixing the above 3 to 5 growing media, four layers are set from the lower part of the pot to the pot rim: drainage, aeration, nutrient, and stem-fixing and pot-surface layers. The nutrients, moisture, and porosity of each layer present different gradients, which can not only meet the different nutrient needs of old, mature, and young roots, but also retain water and allow aeration, significantly reducing the risk of root rot caused by excessive water and fertilizer, thereby achieving the orchid-growing effect of well-developed roots, early sprouting and rapid growth of orchid shoots, and jade-green, glossy orchid leaves. The types of materials used in each layer are roughly as follows: (1) The lower part of the pot, 1/4 thick (the height inside the pot body, the same below), is the drainage layer, with several pieces of tile overlapping to cover the drainage hole at the bottom of the pot, filled with broad-bean-sized charcoal and crushed brick and tree pieces, which have large pores and can maintain water drainage function for a long time. (2) The lower-middle 1/4 thick is the aerated base fertilizer layer: wood chips account for 50 percent (volume ratio, the same below), mountain soil or round soil granules 20 percent, and the remaining 30 percent uses rotten wood granules, peat granules, peanut shells or walnut shells, weathered rock granules, etc., plus one spoonful of fermented oil cake, mixed and then potted. The particle size is pea-sized; the wood chips can either be spread as a single layer over the drainage layer or mixed with other substrates. (3) The middle part of the pot, 1/4 thick, is the nutrient layer, with mountain soil or peat granules accounting for 60 percent, wood chips 20 percent, and weathered rock granules or crushed brick granules 20 percent, mixed and then potted. (4) The middle part of the pot is the stem-fixing and aerating layer, with relatively low fertility. Wood chips account for 60 percent, and weathered rock granules and crushed brick granules account for 40 percent. (5) The fourth layer is the pot-surface layer; on the prepared arched pot surface, a layer of sphagnum moss or rice-grain-sized rock and crushed brick granules is spread, with the purpose of preventing the pot surface from being washed away when watering. The amount of wood chips used roughly accounts for 50 percent of the volume inside the pot. After 6 years of practice in growing orchids by the above method, no root-rotting phenomenon has been observed (for raw orchids, do not add oil cake; for mature orchids, fertility must be increased). After 6 to 10 months, because the wood chips decompose and settle and the pot soil sinks, when the pseudobulbs and orchid roots become exposed, there is no need to repot; instead, add wood chips and several substrates (each at 50 percent). In the first year after potting, the soil does not need to supply fertilizer. In the second year, because the wood chips, rotten wood, tree bark, peanut shells, and walnut shells slowly decompose to produce organic nutrients, part is carried away by watering, and another part is absorbed by the orchid roots or fixed by the soil granules, brick granules, and rock granules after being absorbed, and is also absorbed by the orchid roots, significantly promoting root development. If the leaf color is on the lighter side, the amount of fertilizer applied may be increased according to different situations. Other maintenance methods can proceed as usual. (Zhang Zhengguo)