★Orchid Growing Notes: Sawdust
Growing Orchids
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Early this year I brought home some Tongjiang Chunlan (Cymbidium), and being in a hurry with no suitable material at hand, I rushed to the timber market and hauled back a large fiber sack of Chinese fir sawdust. I mixed it with the old medium I had used for many years at a ratio of 4:6 or 3:7, and hastily potted them up, 5-12 shoots per clump. After more than a month, while observing the growth of the orchid shoots, I found thatorchidswere growing well, and most of the shoots had produced new buds that emerged from the soil surface one after another. In order to more accurately grasp theorchidgrowth conditions, I decided to repot and observe.
In the several pots of orchids I turned out, I felt the bottom of the pots was rather moist, but most had sprouted new buds. What stood out most was that the orchid roots were thick and the buds robust, and not a few had produced double growths - the results looked very good.
Sawdust. Actually, I had used it back when I was a beginner, and the results were about the same. It was just that at that time, being a novice, under the guidance of this old master and that seasoned grower, I switched growing media many times, and felt the orchids were being grown worse and worse…… It seems that whether orchid growing goes well or badly, one must have one's own system; learning from here and there may not suit one's own management style.
Sawdust is soft, light, not prone to compacting, loose and breathable - especially Chinese fir sawdust, which is also easy to obtain. Sawdust is freshly sawn, so it carries few pathogens itself; using it to cultivate orchids gives well-developed, snow-white, thick roots whose tips are not prone to blackening. When using it, there are two approaches:
First, fresh sawdust mixed directly with granular growing material; the ratio should depend on the management environment and method. At present the sawdust-to-granule ratio I use is between 4:6 and 3:7. The first settling-in watering must be thorough; by the third day a pot that has been watered through will certainly have a slight musty smell - this is the sawdust fermenting - so a thorough flushing watering must be done to promptly remove the acidity produced by fermentation. When first using fresh sawdust, during the fermentation peak at around 30 days, water thoroughly more often; the moisture can ease the harm of this acidity, and at the same time, during fermentation this acidity actually acts as a catalyst for promoting buds and roots.
Second, use it after fermentation: before planting, soak it in water to ferment, and further sterilize it by sun exposure or fumigation with chemicals.
Orchids grown in sawdust have robust shoots and lustrous leaves, and a high rate of flowering and sprouting. But as long as temperature and humidity are sufficient, stray fungi and mushrooms easily grow; if not removed in time, the mushrooms topple over in the pot and rot, attracting flies and bringingpests and diseases. After fermentation, part of the sawdust rots and becomes fertilizer, invisibly providing nutrients for the orchids. But the hardest thing to master when using sawdust is that when the pot dries out completely, sawdust does not readily absorb water; dry sawdust is hydrophobic and repels water, so the orchid roots get no water and suffer dehydration. And when there is too much water, it does not dry out for a long time - during the plum rain season one must be especially careful. Mixing orchid stone granules into the sawdust is precisely to alleviate this problem. When watering normally, observe the moisture in the pot more often, and guard against dry outside and wet inside, or too dry or too wet, so as to avoid causingorchidharm.