Quote:
Originally Posted by inkcube
she was wrong, cambium is present throughout bark in various forms; vascular cambium, cork cambium - the cambium layers will not separate from soaking. cambium is not easily separated by water. the main reason to soak is to waterlog the bark to ease the stress of repotting plus it is difficult to get the bark fully wet when potted dry, many commercial mixes will add a surfactant to help the waterlogging process. mulch bark is often treated with chemicals that orchids are sensitive to plus the bark used in some mulches is not fir and can be toxic to orchids. bark is a natural potting substrate for any orchid that is an epiphyte; it provides good drainage, air circulation, and won't retain salts to the same extent that soil & moss do.
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You may have misread the intent for soaking. It was not to separate the cambium from the bark. Rather, it is to separate the bark
with cambium layer attached to it, from bark
with no cambium layer attach to it. Waterlogged, the one with the cambium layer will sink. The pure bark will stay afloat. For this intent, she was correct, at least from my experience. She was concerned about the "liquor" (which you call tannins and phenolics) and its effects on the plants. Even though it was expensive (I could only net 40% to 60% pure bark), I wanted to do it because I got very favorable results compared to not doing it.
Quote:
Originally Posted by inkcube
fir bark is pure bark. there are numerous studies showing that bacteria on the bark used in orchid potting is responsible for N breakdown consumption and bark breakdown.
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I can accept that explanation. But the fir bark, as sold in nurseries or orchid stores, is not pure bark. Some of them even contain wood in addition to the cambium layer. The process for removing the bark from the tree is different for those intended for orchid culture than those for other applications, e.g., mulch, etc. Although hydraulic pressure is used for orchid bark, nevertheless, a good amount of cambium layer remains attached to the bark. And since the wood and cambium layer possibly have more retained sugar than the bark, I would submit that bacteria, and mold, will propagate faster in it. Now, I like to emphasize that I'm making a distinction between the wood, cambium layer, and bark.
Isn't this how they make wood alcohol?
Quote:
Originally Posted by inkcube
what you are seeing here is the tannins & phenolics leaching out of the wood and both can be toxic
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Where there are less of, or at least not readily expelled as from wood, from pure bark. If these are toxic, how do you think they will affect the tender roots of the banana that's just been pulled out from its home soil, transported in various weather conditions, subjected to impact in transit, then replanted in a different soil, and is struggling to form new roots?