Jim,
You may recall this posting by Roth: see the last paragraph
Some Orchiata related remarks
There has been a lot of questions about Orchiata here and there, so now I make a sum up, after all I am tech advisor
As to the background and to avoid any questions as to why I post here or my purpose, yes I am paid by Orchiata to offer advise, especially to large commercial nurseries, fine ideas to improve it. However I am not paid by pallet sold and the large nurseries make the major part of Orchiata trade in the world. It is currently the first bark used in Japan, and along with Sphagnum Moss, now from Pacific Wide as well, I woudl say that Pacific Wide supplies most of the nurseries in Japan, directly or indirectly..........
(I had to remove some of the text to fix it in!)
...........There are some remarks to do about using orchiata:
- All the 'pine bark' are not equal. As an example, using fresh Pinus maritimus bark will destroy the roots. Some famous nurseries in France lost thousands of plants because of 'too fresh bark', that's why some publications advised about composting bark, where some advised using fresh bark. They were from different tree species, and their behavior were different.
- Orchiata and fresh Pinus radiata bark (sold under the name Kiwi amongst others) are vastly different products. Orchiata has been aged, the structure has been made hydrophilic, the pores have been opened during the process, and lime is applied to raise the pH. Fresh pinus radiata is usually hydrophobic, so when it is dry and watered it does not take water immediately, where Orchiata does. It has a low pH as well ( and the competitor's grading is more primitive too to be honest). Fred Clarke use fresh pinus radiata successfully so far, I will comment on that later, because it has involvements in the feeding program as well.
- The tannins and terpenes in Pinus radiata are different from the ones of the Rexius, Sequoia, or European barks. They do not stunt the roots. The structure in general of Pinus radiata makes it very stable, because the bonds are different from others pinus species, as long as they are grown in specific environment. Too hot countries or too cold, and the bark either delaminates or collapses. That's why Chile at a point tried to supply orchid bark made from Pinus radiata, but the way it grows in Chile makes it unsuitable without any questions.
- It is impossible to give advise for 'bark' like that. Depending on the type, the species, the process, there are many different reactions to be expected. So I will limit to Orchiata in this post, though if anyone has specific questions about other types, feel free to ask.
Orchiata should not be soaked in water to remove the materials that falls down at the bottom. This was valid for other types of bark, to remove some unsuitable materials, rotted pieces, wood... However Orchiata has been made HYDROPHILIC, so a fair part will indeed fall at the bottom of a bin. This is normal
Some people soak Orchiata anyway. I do so for some very expensive plants, just to have a peaceful mind, however the dust in itself is washed away after some waterings and I did not notice any difference, so I prefer to use it out of the bag. If it has been soaked, a part of the lime will be removed, and you may need to reapply lime, usually at 3kg/cubic meter. The rough surface of Orchiata chips ensures that the lime sticks well to the bark
Because of the rough surface, when you repot, there will be more air spaces, as the chips will be blocked by each other. Smooth chips of other barks will indeed slip and settle, making a more dense packing.
In the first days I used to mix it the way I did with the european bark, pumice or perlite, or sphagnum. Sometimes coconut products. I did not find any benefit at all, because orchiata by itself retains more water than the bark I was used to, at least in the first months. Orchiata after some years will still retain the same quantity of water per liter, where others barks tended to be hydrophobic at first, then suitable for root growth, then become spongy and deadly after some months or years
Indeed, I found that the smaller grades of Orchiata, Precision and classic, replaced wonderfully well sphagnum in all of its use ( except mounting on slabs of course ). So when I need to make a mix more water retentive, I use something like Classic + Power. For oxyglossum dendrobiums from Papua, I use exclusively the Classic grade.
Some remarks about Sphagnum. Many people have very good results with New Zealand sphagnum, that would be another post. However I do not like it for my plants at all. I found out that in many cases we used sphagnum because the roots are thin, and the plant needs a lot of water, regardless of the pH requirement of the plants. Such examples are Jewel orchids, many are growing on limestone outcrops, and becomes really massive in Orchiata, some of the Oxyglossum dendrobium like decockii, vexillarius... do grow either on rocks or as epiphyte on dead branches, hence the pH of their environment at their roots is neutral to alkaline, never acid. In sphagnum, when the sphagnum becomes sour, and due to the acidity of the sphagnum, the plants are wiped out. cuthbertsonii is way easier to grow in orchiata small grade than sphagnum...
Orchiata has been buffered with lime. As a result, there is a good amount of calcium and magnesium carbonate. The difference with a non processed Pinus radiata bark is essential. Orchiata can be used with both acidifying fertilizer (ammonium/urea ones) and nitrate based fertilizers ( though nitrate based fertilizers have some limitations, except if the plants are supplied with organic nitrogen or urea/ammonium periodically).
Fresh pinus radiata can be used safely for paphs (if it is not limed and aged) and quite a few other orchids only with nitrate based fertilizers such as MSU, because an acidifying fertilizer on an already acid bark would be a disaster.
Fresh pinus radiata bark is very resilient, and very hydrophobic, so it will stay acid for a while, no matter the lime applied outside. That is the main purpose of 'aging' orchiata, to make it hydrophilic, porous, and therefore very 'receptive' to the lime and the nutrient. It avoids too acid release from the bark, because the core of the chips take the water from the first day, where an hydrophobic bark will take the water layer by layer, releasing acid until the bark becomes hydrophilic...
It is very clear too that it is extremely difficult to use only nitrate based fertilizers and get nice plants of many specie. As for myself, I never succeeded, and the Dutches did not as a whole either. You need some urea, ammonium, or organic nitrogen. It has been supposed too that colonization by bacterias, years and fungi of the potting mix could convert nitrate into amino acids in a way, which would explain why some people can grow plants with only a nitrate based fertilizer and nothing else.
As to how to pot in Orchiata, I would say that the best is to mix the various grades ( I never mix it with sphagnum, the results of an Orchiata + NZ sphagnum mix were inferior to pure orchiata when I, and the Japanese tried it) to get the suitable water retention and particle size. Additions of perlite, etc... were unnecessary, perlite or pumice were used first to retain water, but orchiata does retain water already, then to improve the mix structure, but in this case the orchiata structure does not change, even after years of heavy feeding under hot conditions. Mukoyama orchids have plants potted nearly a decade ago in orchiata, as tests, and there are no structure problems.
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