Terrarium moss is the staple plant for any terrarium. Their soft, green texture brings the whole terrarium together regardless of what plant neighbors it has.
Growing moss is relatively easy. It’s a tough plant that thrives in a variety of environments, depending on the species. Most species prefer growing in a cool, humid spot in the shade. For the most part, just keep it moist (but not soggy) and avoid direct sunlight and your moss will be happy as a clam.
But before we get into how to grow moss, it might be helpful to first understand what moss is, how it’s biology works, and where it fits into the natural ecosystem.
What is moss?
Moss is a phylum (a subcategory) of bryophytes containing over 12,000 different species. In other words, it’s a type of non-vascular plant.
This means that moss differs from most other plants in that it produces spores (instead of seeds) for reproduction and they don’t grow flowers, wood, or roots.
Instead of roots, they have little hairs called rhizoids that anchor them to their substrate. Their leaves absorb nutrients from the air and water they come into contact with directly. That’s why most mosses will prefer living in a high humidity environment.
These characteristics of mosses are advantageous for a terrarium because it means your moss won’t be competing with the root systems of other plants nearby and they will be well-suited for the high humidity in a terrarium.
Types of moss
There are several types of moss with different growth characteristics including:
- Sheet moss/carpet moss (Hypnum curvifolium): a type of moss that spreads out like a carpet/mat providing a lot of ground coverage. These are great for planting in your walkway because they can handle a lot of foot traffic.
- Ceratodon moss: moss with colors ranging from yellow-green to red. They grow in tufts about an inch high. These types of moss prefer a little more light, but are also shade tolerant.
- Cushion moss (Leucobryum glaucum): Like the name implies, cushion moss grows in the shape of the pin cushion.
- Rock cap moss (Polytrichum commune): A medium to large-sized moss that grows along rivers streams and more generally in areas with high humidity and rainfall. Fun fact: unlike other mosses, rock cap moss draws water from it’s base
- Fern moss: A category of several types of mosses that produce feathery fronds that look like ferns.
Step 1: Buy moss or harvest your own
There are primarily two ways people get their moss: buying it or harvesting their own.
Technically, you can grow moss from their spores, but that’s going to be more trouble than it’s worth unless you’re some kind of plant scientist. You might also come across moss “seeds” while browsing online, however that’s probably referring to Irish moss, which is not a true moss, but rather a type of algae.
If you’re looking to buy moss, your best bet is to check Amazon or your local plant nursery for live moss. You may also have some luck buying live moss from a small online site that services your region.
My recommendation for anyone new to growing moss is to start with sphagnum moss, although most mosses will work fine.
The one thing to be aware of is any moss containing artificial dyes. If you’re not careful, a green color can bleach out into your terrarium and any give a shade of green to any living critters you might have in there.
Harvesting Your Own Moss
Harvesting your own moss is a relatively simple process once you get the hang of it. Most regions around the world will have moss occurring naturally.
The first place you might want to check is your own backyard. Moss is pretty abundant in most climates, so I’m betting there’s probably a decent collection of moss gathering in your backyard right now.
So before setting out on a 12 mile hike, just take a step outside and look around and see what you find. I like to check the shady, moist areas as that’s what moss tends to prefer.
One of the next best places to check for wild moss is in a nearby forest or your local park. This is the natural gathering place for plants suited for your climate. Unless you’re living in the desert or the arctic tundra I can almost guarantee you you’ll find moss there.
Once you find moss, it’s important to be conservative with how you harvest your moss. There’s no need to scrape off a huge patch of moss leaving a big, bare spot when it’s not necessary. In most cases, you won’t need that much moss.
Just take your finger, feel around for the base of the moss, and scoop up a small patch about an inch wide. I like to collect the patch from the center of the moss so that I can cover up the spot with the surrounding moss. Afterwards, it looks like I was never there.
Step 2: Decide where to place your moss
I won’t get into too much detail on how to build a terrarium here, but if you want to learn more about that, check out this article. Here, I’ll just go over more generally where moss can be placed within a terrarium.
Since moss doesn’t rely on a traditional root system like most plants, their placement can be very versatile. They don’t have to be tied down to soil.
Moss can grow on a variety of substrates including soil, rocks, wood, and even concrete or asphalt. However, each species will have its own substrate preference. I’ve even seen moss grow on an old car.
If you harvested your moss yourself, you might increase your chances of success by allowing your moss to grow on the substrate you found it on. If you can, it might be helpful to take a piece of the wood or rock it was growing on with you and placing that in your terrarium directly.
You can even use plant glue to get really creative. That can be helpful if you’re trying to put your moss on a steep slope.
The other nice thing about mosses is that they don’t compete with other plants in your terrarium. This means that you can use your moss to get some ground coverage near your plants. Moss can also be used as a way to fill in any small bare spots in your terrarium.
Where you place your moss pretty much comes down to a matter of preference. Moss is a pretty hardy plant, so you have a lot of freedom for experimentation when it comes to deciding where to place your moss.
Step 3: Control the light levels
When moss is placed in a terrarium, you want to make sure to give it proper lighting. The best lighting for your terrarium is indirect light.
Most moss will prefer to stay in the shade. Even though some moss species can tolerate full sun, I would advise against placing your terrarium in direct sunlight.
Since your terrarium is (probably) a closed container, sunlight can raise the internal temperature like a greenhouse. When this happens, inside of the container can get a little bit hot compared to what you might be experiencing outside the terrarium.
In direct sunlight, your plants will be at risk of overheating. According to this study that cultivated over 300 mosses, 5-25 C (41-77 F) will be optimal for mosses to survive with variation depending on species. They found that anything above 30C (86 F) will be fatal, so be very wary of high temperatures.
If you want to get scientific, you can also use an artificial lighting lamp with fixed intervals of daily light. 6-8 hours of light at 100W (plenty of wiggle room on the wattage) should be sufficient for your moss.
Step 4: Give your moss just enough water
Most moss will prefer high humidity conditions with a lot of moisture, however this doesn’t mean you can drench your moss 24/7.
Moss can be both under and over-watered. How you tell that will make or break the difference between rotting, moldy moss or yellowing, brown moss.
The first thing you should check to determine the water levels is the condensation. If you see heavy condensation on the container throughout the day, there’s probably too much water. A proper amount of water should lead to condensation on the container in the mornings and evenings.
The next thing you can check is how the soil feels. Just open up your container and feel the soil to see if it’s soggy, dry, or slightly moist. You’re going to want the latter.
If you’re noticing there’s too much water in your terrarium, there’s two things you can do:
- Open the container anywhere from a few hours to a day or two to let your terrarium air out
- Wipe off the condensation on the container to remove water from the system
By avoiding too much water in your terrarium, you are saving your moss from rotting and discouraging mold growth.
On the other end of the spectrum, if you notice your terrarium has too little water, the solution is pretty straightforward. Just add a little bit of water to get the soil moist.
When watering your terrarium moss, preferably you will want to use distilled water or rain water. Moss can very easily soak up metals and any toxins present in tap water, potentially compromising its health.
The quickest way to check how the water levels are doing is to look at the condensation.
You’re also going to want to spread the water evenly throughout your terrarium. It would be best to use a mister or spray bottle to water your moss like the one I recommend here. Just give a few spurts of water all around your terrarium to get an even spread of water.
This will prevent water from accumulating in localized areas causing some plants to be overwatered and others underwatered. This will minimize problems dealing with small patches of rotting and mold growth, especially if any of your plants have a funnel-like shape that promotes water pooling.
How to Propagate your moss
If you want to take your moss growing to the next level or just want to build up an inventory of moss for future terrarium builds, propagating your own moss is the way to go.
Propagating your own mosses very similar to the 4 steps I went through above. The only main difference is you’ll be growing a whole bunch of moss at once rather than small patches here and there.
Setting up the propagation container
First things first, you are going to need a large, clear plastic bin like this one. If you are going to grow a lot of moss, you are going to need a lot of space. Try to find as large a container as you can. The bigger the better.
The setup of the container will be pretty much the same as a traditional terrarium.
First, you’ll put in your drainage layer or false bottom. You can use small stones or sand for this. Just as long as water can flow freely into that layer. You can cover about an inch and that should be good enough.
Next, you’ll add in a separation layer using a porous material or mesh like this one I recommend here. This layer is going to keep your plants from growing into the drainage layer and getting soaked in the water.
Since you are primarily working with moss, this shouldn’t be an issue because moss doesn’t have roots. However, it’s still going to be helpful to separate the next layer you’re going to add.
Once you’ve added the separation layer, now you can add your activated carbon or lump wood charcoal. This will help purify the water as it cycles within the terrarium. Roughly an inch will be fine.
On top of the filtration layer, you’ll add your soil. Since moss doesn’t grow any roots, this layer doesn’t have to be as deep as your typical terrarium build. You can add half an inch to an inch and that should be sufficient.
It can be helpful to spray the soil down after you lay it in so that your entire propagation container will have even water levels.
Preparing your moss to propagate
Finally, you’ll add your moss in. There’s no real rules or requirements for how to organize your moss, but I prefer to spread out the moss evenly so that they won’t get too much into each other’s spaces. That also helps if you’re trying to separate out the different moss species you’ve gathered.
If you haven’t already, give your moss a quick spray down with some distilled water to make sure they have enough moisture before you close it off.
If you like, you can also add some springtails into your container. These will help prevent mold growth by eating up any dying and decaying organic matter.
Once your container is all set up, that’s most of the work done. The last thing you’ll have to figure out is how to handle the lighting. You can use an artificial lamp on a fixed on/off cycle if you like, but indirect sunlight should work fine as well.
Besides that, there’s really not that much to it. Just check on it periodically to make sure the water levels are good and that your mosses are still doing okay (no yellowing, mold growth, rotting smells, etc.).
Speaking of moss health…
Troubleshooting common moss problems
Most likely, you won’t run into these issues, especially if you picked species of moss that tends to do very well in most environments (which most moss are).
Realistically, there are primarily two problems you could potentially run into:
- Browning/yellowing moss
- Moldy moss
Browing or yellowing moss
If your moss starts turning brown or yellow, there could be a few causes:
- Not enough water
- Using tap water
- Too much sunlight
- Your species is not suited for its new environment
The first thing I would check is how much more are you giving to your moss. If there’s not enough water, that could lead to moss turning yellow or brown. If you notice that the soil is pretty dry and you don’t see any condensation in the container, that’s a likely cause.
If giving it some more water doesn’t work, you might want to switch to distilled water if you’ve been using tap water. Tap water often has chlorine which can be harmful to moss.
It’s also possible that your moss could be getting too much sunlight for what’s appropriate for that particular species. It could also mean it’s getting overheated. That can be fatal to many moss species. Try moving your moss to a more shady area and see if it gets its green color back in a week or two.
Lastly, you may want to consider the species of moss you are working in. Is it normally found near flowing water? Does it like to attach itself to wood? stone? These questions can help you change up the design of your terrarium to best match your moss’s natural environment. This will give it the best chance of thriving.
If your moss starts growing mold, most likely that’s because it’s getting too much water. If there’s more water than necessary, it’s very easy for mold to start growing.
You can try pulling off the mold with some tools and then letting your moss/terrarium dry out for a bit. If it’s been sufficiently dried out, the mold problem should resolve itself in a few days.
The alternative to letting it dry out for a bit is to include some springtails in your terrarium. These guys will eat up any dying or decaying organic matter including mold and fungus.
So there you have it. Four easy steps to grow your moss. My recommendation for anyone looking to get started is to just go for it. Don’t worry too much about failure, it’s pretty easy to restart with some new moss and try again. Experimentation is all part of the fun of growing terrariums.