Many people think that the brown, dried moss from the store is pretty dead. But one day you found a little green on the top layer of some wet moss.
Can dried Sphagnum moss come back to life?
You cannot revive the dried sphagnum moss from the stores because they have been dehydrated for too long. Those who think they have successfully revived dried moss most likely mistake the new growth for algae or seedlings of other plants, or their moss comes with spores.
Let’s first look at whether sphagnum moss can tolerate dehydration. We will also show you how you can grow sphagnum moss from live ones in case you want to grow orchids with live moss.
1. Is sphagnum moss tolerant to desiccation?
Sphagnum mosses are considered “poikilohydrous”. This means that they lack the ability to regulate the water content inside the plant in relation to the environment. For example, when the environment is dry they would fail to hold water inside the plant.
This shortcoming is compensated by their high water retention capacity. Depending on the species, Sphagnum moss can hold 16 to 26 times its dry weight in water by storing the water in their cells.
Their high water retention ability enables them to be rather tolerant to dehydration for a short period of time without physiological damage.
2. How long can sphagnum moss tolerate desiccation?
When there is not enough moisture in the environment, sphagnum moss does not die right away, they go brown and dormant. The length of the period for how long they can tolerate desiccation depends on the species of sphagnum moss. But, leaving the moss dry for 1-2 days should not kill it.
A study by Wagner and Titus (1984) shows that Sphagnum fallax, a hollow species, can recover after up to 5 days of dehydration and also can also survive with 10 days at low water levels, which is a higher capacity than Sphagnum nemoreum Scop, a hummock species.
3. Can dried sphagnum moss be revived when rehydrated?
If sphagnum moss can tolerate a bit of desiccation, does that mean we can bring dried moss back to life by rehydrating them?
If the moss you have is harvested from nature recently, you maybe able to revive them by rehydrating them.
But if the moss you have comes from the store, it is virtually impossible to rehydrate them. The problem with the dried sphagnum moss sold in compacted bricks in gardening supplies stores is that they have been dehydrated for a long time before you buy them. There is no way that they can come back to life even though the moss is tolerant to desiccation for a while.
Some people believe they had “success” in reviving dried sphagnum moss. There are only three possibilities: 1. They probably mistake the new growth for green algae, which has a dark green color – different from the bright green color of live sphagnum moss. Also, if your dried moss becomes green within a few months, it is most likely not live moss because the growth of moss from spores (seeds) is very long, taking at least 9 months. 2. It could just be a weed seedling. The bricks of dried sphagnum moss are full of seeds from other plants. If you use new sphagnum moss, it is common to get sprouts. Pay attention to the shape of the sprouts if they have smooth grass-like leaves rather than fuzzy leaves like moss. 3. Another possibility is that the new growth is indeed new moss because the dried moss from the store comes with spores which are fine dust-like seeds stored in brown-colored capsules. But again, it takes at least 9 months to grow from spores to moss.
4. Does dried moss have spores?
How do you know if your dried moss does come with spores?
Check if the moss has a tall, thin stalk structure supporting a little brown capsule (as in the picture). The capsule produces spores which are essentially seeds resembling fine dust that will germinate if they land on a moist surface.
5. How can I grow sphagnum moss?
If your dried moss does not come with pods with spores, you can still propagate sphagnum moss asexually by using some starter live moss.
You can divide an existing clump of live moss and place the pieces into a container with a growing medium, such as peat, soil, or just a cloth. You can also trim the heads and transplant them into a new surface and they will start growing there.
The key is to provide enough and constant moisture (watering like 2 times a day) away from direct sunlight. The best is to use rainwater instead of tap water.
The ideal place to grow moss is in a shaded place with temperatures between 50 and 70 degrees Fahrenheit, protected from direct sunlight. It likes a very week fertilizer. Too strong would kill the moss.
6. How long does sphagnum moss take to grow?
Spahgnum moss grows very slow from spores. It could take at least 9 months to have some significant growth.
From cuttings, it can take a few weeks to grow longer. It grows between 0.75 to 4.75 inches per year.
To sum up, sphagnum moss can only tolerate around 5 days of complete desiccation. It is impossible to revive the dried moss bought from the store because they have been dehydrated for a long time. Next time when you see some greenery showing on your moss, check if it is just algae or a weed seedling.
Tomáš Hájek & Eliška Vicherová (2013). Desiccation tolerance of Sphagnum revisited: A puzzle resolved. Plant Biology 16(4):765–773
Daniel J. Wagner and John E. Titus (1984). Comparative Desiccation Tolerance of Two Sphagnum Mosses. Oecologia, Vol. 62, No. 2 (1984), pp. 182-187.