Phalaenopsis Orchids and Bark Media Facts

September 24, 2019

I done research on bark media for Phalaenopsis Orchids, and would like to share some facts I found interested for me.

Orchids, which are growing in bark, usually need extra nitrogen for green growth, and in order to compensate for the decay organisms’ demand for nitrogen. Fertilizers with a 30-10-10 ratio of nitrogen, phosphorus and potassium represent the grow formula.
Bark media goes through a stage of rapid drying, and usually within a month after re-potting, the bark becomes “seasoned”, or thoroughly moistened. Once this is achieved, organic decay of the bark begins in earnest, with the proliferation of decay microorganisms which themselves require nutrients, particularly nitrogen. This decay continues, and generally within two years the bark is reduced to fine-particled humus, a decay-resistant material capable of retaining large amounts of water and nutrients. That’s why recently re-potted plants are likely to need more frequent watering and fertilizing than those which have been re-potted for a year or more.

One can think, oh well, if bark became decay-resistant material capable of retaining large amounts of water and nutrients in two years, why bother to re-potting? But this reduced porosity has a significant drawback in that it greatly reduces the oxygen level of the mix — particularly when it is wet, so roots begun to decompose. Roots cannot function without adequate oxygen, and Phalaenopsis roots especially seem to require excellent aeration.  Phalaenopsis potted in dense media often produce roots which refuse to penetrate the mix, moving instead along the surface and over the side of the pot. 

This question was always bothering me: why some Phalaenopsis had too many aerial roots and some doesn’t. Seems the answer is simple – roots are not happy inside the media…… What do you think about this?


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