Potting Orchids in Sphagnum Moss
This guide describes one method for potting orchids in sphagnum moss so the chance of over watering is minimized when the plant is watered on the same schedule as plants in more common media such as bark mixes or coconut husk.
Many orchid sellers deliver some or all of their orchids to customers potted in sphagnum moss. It is not uncommon for the buyers to be given no information on how to care for the plant in this media. As a result, some buyers have negative experiences that could be avoided. For a list of these considerations see special considerations for growing orchids in sphagnum moss, at the end of the guide.
SOFT OR HARD PLASTIC POTS STUFFED WITH SPHAGNUM
The use of sphagnum to stuff a very low cost flexible or hard plastic pot is a low cost potting solution that some growers prefer. Most collectors will therefore receive an orchid potted in one of these pots from time to time. The danger with these pots is that soaked media can remain wet for a very long time, suffocating roots and providing an ideal environment for fungal or bacterial infections. Getting the media too wet when watering can result in complete destruction of the orchid's root system. Another way the media can become far too wet occurs when the moss wicks up water from the bench. Both these possibilities should be kept in mind when a new plant arrives potted in sphagnum. Water just enough to moisten the media but avoid giving so much water the media becomes glossy, heavy or soaked.
AN ALTERNATIVE METHOD BETTER SUITED TO MIXED MEDIA COLLECTIONS
We've found that a potting method similar to one used by Alan Kotch at Gold Country Orchids works very well for most orchids. What makes this method inviting is that with a little care the plant in sphagnum can be placed on a bench with plants in other media and watered the same way. The following annotated diagram describes the method almost completely.
A ceramic pot is used to help dry the media and assure oxygen is available to roots. When the surface of the pot is no longer clammy, it is usually time to water again. The pot is chosen much smaller than for bark media to keep the amount of moss small and drying time to a minimum. This method is therefore best for smaller plants and is especially well suited to terrestrial orchids and orchids that enjoy constant moisture at their roots. It is poorly suited to plants with a sprawling growth habit and plants that are very sensitive to over watering.
The air gap at the bottom of the pot prevents water from wicking up into the sphagnum but also provides a cavity that can become filled with some of the healthiest pure white roots you'll ever see. The sphagnum potting media should be packed hard to provide support and reduce the rate of absorption when watering and the amount of water that is absorbed during watering.
Potting an orchid as shown in the diagram above is a three-step process. Different people may use different methods, but the goal is the same. Fill the upper part of the pot with sphagnum packed firmly enough to hold the plant upright, while preventing the media from occupying the bottom of the pot.
1) Create a flattened sphagnum plug around the roots of the plants using enough media to assure the plant is supported after it is inserted into the pot. This may require some trial and error to accomplish.
2) Push the flattened plug into pot.
3) Clean up the moss along the edges by removing it or tucking it into the pot while assuring that the plant is at the correct level in the media. If the plant is not supported well by the moss and falls over, or if it is sitting very wrong in the pot, it is best to adjust the amount of media and try again.
There is no single method for accomplishing the above. Different people go about it differently, and different size plants require different approaches. The example above shows one way to get to the goal providing the basis for the improvisation that is needed with variations in plants and pot sizes.
SPECIAL CONSIDERATIONS FOR ORCHIDS POTTED IN SPHAGNUM MOSS
Plants correctly potted in sphagnum must be watered judiciously to prevent saturation of the media. Misting systems and daily sprinkling must be done carefully to assure that moisture is not added to the media at a rate that keeps the media from drying out completely within a week or so.
Water moss normally before applying water soluble chemicals, such as fertilizers or pesticides. It is risky, for example, to apply liquid fertilizers to dry moss. Moss can hold a tremendous amount of liquid. As the water evaporates or is absorbed by the plant, the fertilizer salts become more concentrated in the remaining liquid. At best the result may be over fertilizing of the plant, at worst the fertilizer may burn the roots badly enough to kill them and may even kill the plant.
For a guide on how to pot Neofineia falcata or other orchids in sphagnum moss using another very successful method developed in Japan, see the April, May, June issue of Orchid Digest.
All rights reserved.