Phalaenopsis orchids should be repotted every one to two years to refresh the potting medium and provide a healthy growing environment for the orchid (see our previous post). In the U.S., orchid bark and sphagnum moss are the two most common components in commercial orchid potting media, but a wide variety of other materials may be added to the mix.
Whether purchasing commercial orchid potting media or making your own, it’s helpful to know what different ingredients bring to the mix:
Orchid bark, actually the bark of Douglas fir or redwood trees, is inexpensive in the U.S., drains quickly and deteriorates slowly, requiring repotting only once every 2 years.
Sphagnum moss is often paired with orchid bark because it helps retain water, preventing moisture from draining away before it can be absorbed by the plant’s roots. It is also believed to help prevent fungus. Select long-fibered, premium grade moss that is free of debris. Because it breaks down quickly, moss must be replaced annually.
Tree fern, the rigid, dark-brown roots of a Central American fern known as the “tree fern,” is easy to use and can stay fresh for up to three years. Its drainage properties are similar to that of orchid bark; but because of its greater expense, it is less commonly used in the U.S. than bark.
Osmunda fiber was once the orchid potting material of choice, but expense and limited availability have dropped it from favor. It is also arduous to cut into potting-size pieces and must be carefully aligned to drain correctly, making it an impractical choice today.
Tune in next time to learn about some of the more unusual components that are sometimes added to potting mixes. Until then, check out our orchid repotting video here.