photographer and orchid grower. Responsible by the sites The Orchid Photo Page and The O Zone (on-line magazine about orchids)
Delfina & Sergio,
This is a great issue of Orchid News and you are certainly providing a
service to the global orchid community by bringing the crisis of the tree fern's threatened survival to the forefront.
In some ways it is a problem for orchid growers and in some ways it is
not.
If a whole collection or commercial enterprise is geared to using tree fern as a potting media then having to adjust cultural practices to a new material is a problem.
However, as you are aware, epiphytic orchids will grow in or on almost anything that is not objectionable to them, the potting material is merely a support. I have seen orchids grown in glass marbles
in styrofoam pots, Vandas grown in old beef bones, Oncidiums grown on
slabs of styrofoam, Encyclias grown on cow skulls, one of the healthiest C. aclandiae I ever saw was growing on the outside of a clay pot.
I think the loss of tree fern as a potting material is more of a
loss to commercial growers with a profit motive and thousands of plants
than individuals with a few hundred orchids who can, and usually do, experiment with other potting materials.
In the US, tree fern has been expensive and occasionally hard to find for
several years. Many growers have already found other media. As is mentioned at your forum, many growers here use fir bark which is relatively inexpensive and readily available.
Indeed, along with sphagnum moss, it is probably the most frequently used material for growing orchids, especially for growers in temperate areas.
Here in South Florida it deteriorates far too rapidly for our use.
A few years ago we began moving all our orchids out of tree fern and into
lava rock, this was the best thing we ever did. Our move to lava rock was a cultural move, not a response to dwindling tree fern supplies. We grow our mixed collection of 700 plants in an open shade house in South Florida where they are subjected to extended rainy spells and warm
temperatures.
Although tree fern had been a reliable media for us for
decades, the inorganic material is proving to be superior. I should add here that we use sphagnum for Phals and some species grown in baskets and mounts for species that need them.
The advantages of inorganic media are:
they cost a fraction of tree fern and are readily available
they have good moisture retention
they are easy to pot with
they NEVER break down meaning you only repot when the plant
outgrows its pot, there is no danger of root loss caused by deteriorated medium
old potting media does not need to be completely removed from
the roots when repotting meaning less shock to the plant
There are only one or two possible drawbacks:
They can retain fertilizer salts over time and burn root tips in
some species, deep watering monthly eliminates this problem.
They are heavier than organic materials, for some orchids
(Phals, Mtssa, etc.) this is an advantage.
Lava Rock (left) and Aliflor (right)
There are several of these inorganic aggregates; Solite, Aliflor and Lava
Rock all share similar properties which differ from expanded clay in
having tiny pits in the surface to retain moisture. As I mentioned earlier, orchids can be grown in almost any simpatico material providing that cultural practices are adjusted accordingly.
In closing let me offer my Rule #1:
Before moving your whole orchid collection into a new potting
medium experiment with a small number of orchids (preferably duplicates)
in that growing medium for at least one year or a full change of seasons
whichever comes first.
Greg Alikas
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