Orchid Growing Substrates

Standalone products
Apart from Orchiata, there are some ‘popular’ standalone products, rockwool, sphagnum moss and Tree fern.
For the commercial grower or the caring hobbyist it is the best in a way, if the media is suitable by itself.
- Rockwool has been commented earlier. One of the problems too is that, once it has been pretreated
for use, when potting, the pressure applied will change its behavior in the pot. Sometimes too the
rockwool cubes can collapse under the finger’s pressure, not a good sign that they are as ‘stable’ as
claimed.
- Sphagnum moss. It is a strange media in some ways. When very loosely used, as few fibers in the pots,
it dries up very quickly. When packed reasonably, it can retain a lot of water. When packed and
stuffed in the pot until it is borderline concrete hard, or nearly so, as it is the current practice of many
nurseries, it retains much less water. However, tight packing makes it less water retentive, but can
build up decaying bacteria’s, that the roots can take up. People that pack it very tightly usually do not
water as a drench, rather they moisten it regularly. It needs to be repotted, with some marginal
exceptions, quite frequently. In Taiwan, the rule is to repot every 3-4 months at the maximum, very
tightly packed. They use very soft pots, which tend to collapse a bit on the side, which keeps the sides
of the sphagnum potted plant well aerated too. They use heavy feeding schedules too, but only
moistening the sphagnum moss. In that they are very successful. In Japan, some growers use only
New Zealand sphagnum moss to grow their Paphiopedilum, though the plants do not look like so
happy, except with very frequent repottings, and quite hard water, where they still need quite
frequent repotting. The Maudiae types and some of the species behind are well suited to New
Zealand sphagnum moss as a single potting material. On the other side, the Parvisepalum can perform
well in Chinese sphagnum moss, not in New Zealand sphagnum moss, for the reasons explained
before. Chinese moss has a lower buffering capacity and water retention, so its pH can go up in an
easier way. It requires first high quality Chinese sphagnum moss, which is usually harvested by orchid
collectors on special requests with very frequent repottings. But Xavier saw big clumps of all the local
Chinese Paphiopedilum species in it. One more problem, it is suitable for cool to cold growing
climates, as the Chinese sphagnum moss will spoil very quickly if the temperatures are intermediate
to warm. Yet it is worth to mention it.
- Tree fern has been covered previously, as said, it is one of the best potting mixes along with Orchiata,
yet it is not available in reasonable quantities, its export is banned from many countries, and it is not
really ecologically harvested. It is expensive to get good quality, more than to import Orchiata bark in
Vietnam, if one wants the good quality tree fern. It is popular in Malaysia and Indonesia, where some
massive clumps of Paphiopedilum can be seen. Like Orchiata, it is very long lasting and retains its
structure for a very long time. Unlike Orchiata, it is very acidic and needs sometimes heavy pretreatments,
and unlike Orchiata, it really destroys the ecosystems.
Xavier Garreau de Loubresse
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