|Today, sterilized fir bark
is probably the most commonly used orchid potting material. Its ease of
use and comparatively low cost make it an excellent choice for growing
orchids of most genera. Sterilized fir bark comes from several species
of Western U.S. trees including White Fir and Douglas Fir. It is cleaned
and graded before being offered for sale as a potting medium. Fine grades
are suitable for seedlings, whereas coarser grades (pieces up to 1-1/2")
may be used for large pots. As with other materials, fir bark may be enhanced
with additives such as perlite, charcoal, aggregates or redwood chips. These are
often sold as proprietary bagged mixes.
Potting orchids with fir bark is easy; the relatively uniform pieces readily fall into place among the orchid roots. Because fir bark may be resistant to water at first, many growers prefer to soak it in warm water with a few drops of liquid detergent before using it. This also serves to remove some of the dust generated in shipping.
Bacteria which feed on the bark and bring about its eventual decay may use all the available nitrogen leaving orchids nutritionally deficient. Therefore, it is necessary to use a high-nitrogen fertilizer (such as 30-10-10) for orchids grown in fir bark.
In a controlled environment, fir bark may last two years in a pot. It has a tendency to break down much more quickly in warm sub-tropical conditions and therefore is not used there as frequently as tree-fern or aggregates.
medium fir bark
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