Easy on the hands
Balances moisture and air flow
Loved by most orchids
That’s my haiku about sphagnum moss. When I give an orchid talk, the topic invariably turns to how to care for whatever orchids I am discussing. Care includes watering, temperature, light, and potting preferences. That always leads me to ask the group, “How many of you HATE moss?” I have found that the number of hands that go up depends very much on the part of the country I am visiting, but I don’t think it should. People who know me know that you can not disparage moss without a fight from me!
Why do I love sphagnum moss? It is the most versatile of all potting media and it has the added benefits of not falling out in the event of an overturned pot and being very easy to work with. I admit that while I do pot a few orchids in bark, I hate doing it because it’s not easy to get the bark in among the roots without damaging them in the process and getting micro-splinters in my fingers to boot! Moss, on the other hand, is soft and easy on roots and fingers. But that’s not enough to make me use it. I prefer moss because I think it’s the best choice for the plant.
Sphagnum moss is a natural sponge. It holds many times its weight in water which means that it can keep humidity around the plant’s roots for a long time. I find that southern growers and growers in warm climates in general favor moss because at their temperatures, plants dry out very quickly. Moss gives them a couple extra days before they have to water again. The moisture retention capacity of moss is especially excellent for plants that love water, such as bulbophyllums and pleurothallids. You can pot plants in moss and set them in water—not something you generally want to do with most other orchids. Personally, I find it easier to determine when moss is dry than when bark is dry because moss is essentially weightless when dry. It also changes color and texture when wet (darker and softer), so you have a lot more clues to go on than you do with bark.
I know some of you read the previous paragraph and were shouting (perhaps just in your head—I hope), “That’s exactly why I don’t use moss!! It never dries out!!” Ah, but it’s all in how you use it. The other magical property moss has is air pockets. Air around the roots is essential for all those fat-rooted genera like vandas, cattleyas, phalaenopsis, and dendrobiums. Their roots are adapted to drying out BUT also to having high humidity. To maintain those air pockets, use a light hand with the moss. Put a little moss in the center of the root ball along with something non-absorbent like an inverted net pot, a Styrofoam peanut, or a wine cork—cheers! Then gently wrap the outside of the root ball with a thin layer of moss. Slide the plant into the smallest pot the roots will fit into comfortably, and you are done. If you’re still worried about insufficient air and excess moisture, put the plant in a net or clay pot for faster drying.
You know those phals you buy at the grocery store (or your friend gives you when she has almost killed hers)? They come packed within an inch of their lives in moss. This is one of the reasons moss gets a bad name. When dry, super-compressed moss is almost impossible to wet without prolonged soaking. Once wet, it may stay wet until the next century. This, of course, leads to root rot and a slow death for the plant. Why do they come that way? For shipping, of course. Remember how I said that moss is great because it doesn’t fall out of the pot? Yeah, there you go! If you pot the way that I suggested, however, your plant SHOULD fall out when you turn it upside down!
If there is one drawback to using moss, it’s that moss deteriorates faster than bark. Plants that stay pretty dry most of the time can go up to two years in moss, but really a year is better. If I am adding media to a basket, I do not use moss because I don’t want to change it out later (way too lazy for that). Related to this, sphagnum grows algae and sometimes other mosses on its surface. Those spores are always present in the air, and sphagnum is a happy home for the spores. The algae/moss doesn’t hurt your plant one bit. I think it adds a little character to the plant. On the positive side, regarding repotting, because moss is so soft, I repot plants year-round as I find time (please no letters about what a bad idea this is). The moss doesn’t break newly forming roots, so I just have to watch what my fingers are doing.
I am happy to say that I have made some moss converts by correcting the heavy hand that many people use when potting in moss. Some have even become real moss disciples. The next time you repot a plant, particularly if it is a moisture-loving species, give moss a try. I think you will be pleasantly surprised at your root growth and that is the key to all orchid success!