Making moss terrariums – or not…

When glass gathers moss , the glory is intensified. By night, glass glistens from the light of a firefly or the stars shining from above. Inside, glass glistens, too, as a reflection from candle light’s soft glow. By day, glass becomes a vessel, flattering all that resides, elevating the status of the moss garden below.

This covered dish, contains Asplenium platyneuron (ebony spleen wort), Dicranum scoparium, Leucobryum glaucum, Hypnym imponens, and Campylopus introflexus.

The dish appears to be very terrarium-esque, but mosses do not make ideal terrarium plants.

David Spain advises creating this type of covered dish garden for short durations, “To enjoy the beauty of the cloched moss garden for a brief period, like over a weekend or when friends come over for good conversation. When the moss dish garden is not on “show” remove the glass to better regulate the moisture content and air circulation.”

With a renewed popularity of terrariums, and the desire to be around mosses, many are using moss in their designs. The guidance below, may help your mosses thrive under terrarium conditions. For the best results, consider creating your terrarium like David did above; by day, uncovered, a lovely moss dish; by night, a glistening, globe of glass covering a garden.

When we think of a terrarium, we envision a tiny rain forest-like environment, dripping with condensation, mimicking a constant rainfall. Many plants will tolerate this in a terrarium; however, mosses will not. Mosses need good drainage. In addition, mosses need air circulation.

As David explained, “Closed terrariums are a problem for mosses because they trap too much humidity and the lack of air circulation is a breeding ground for mildew.”

Not all mildew is a problem, just the ones that feed on the mosses and have a mold-like appearance. According to David, “Grey to black and powdery types of fungi, spell trouble in a closed container.”

“It would be nice if we could put some moss in a sealed container and have a complete self-sustaining ecosystem, never to be touched again, but this isn’t the case,” says David. “Opening the container to allow for evaporation is how you adjust the humidity level and it also allows for an exchange of gasses. Even when humidity levels are correct, lifting the lid for gas exchange is periodically needed.”

If you want to keep mosses alive and healthy in a terrarium, special care must be taken to achieve the proper level of humidity — one that is moist enough to hydrate moss but not so moist for mildew to thrive. If large droplets form on the inside of the glass, then it’s too wet. The optimal amount of condensate would have the glass looking slightly hazy or with no condensation present, at all.

As with any type of planting arrangement, group plants with similar needs together. This becomes a problem for mosses when trying to pair with vascular plants. “Vascular plants need water in the substrate to survive, but this amount of moisture will overwhelm the moss and create heavy condensation,” says David. “A solution is using plants that will tolerate low levels of light and moisture.”

To help mosses and vascular plants co-exist, David recommends, “Periodically, removing the lid, watering the vascular plants, and then replacing the lid a day or two later.  Once the lid is returned, check for condensation; keep this venting/sealing process going until you achieve the right balance.”

“This may seem like a lot more maintenance than a terrarium is supposed to receive, however, the truth is, few terrariums are carefree in the long run and mosses are not ideal inhabitants,” says David

Mosses need drainage and won’t tolerate sitting in wet soil. When making a moss dish, providing drainage is important. Without proper drainage, you can’t leave the terrarium outdoors where it will fill with rain water. When this happens, you’ll have to tip to drain.

With drainage, there is no fear of leaving the terrarium outdoors for a rain respite; something mosses appreciate. However many glass containers, such as those used in terrariums, are difficult to drill.

For non-draining containers, activated charcoal, properly rinsed and drained and mixed with gravel to absorbs accumulated pollutants, is necessary.

Be sure to supply bright indirect light. Keep the humidity level as low as possible and ventilate often.

There are opened top or vented containers that make the humidity balanced and gas exchange easier and there are plants that welcome these conditions, as well.

“Many of us desire to have our flora cohabiting with us indoors and mosses are no exception. Creating a proper environment can be a challenge, but control of a terrarium is one way, says David”

As a side note, this cloche and dish were not a set.  The cloche and dish were purchased separately, then paired up.  You may be surprised how easy it is to find cloches to fit over a dish, creating the perfect cozy for your moss garden.

From my perspective, I like the compromise of occasionally doming the moss dish with a glass cloche for times when I want to show off, errr, I mean show case, then removing the glass during off hours. This way, I have all the drama a terrarium provides, but with little maintenance and worry wondering if my mosses will thrive.


David’s recommended picks to use in terrariums or indoor containers.

Campylopus introflexus
Climacium americanum
Dicranum scoparium
Hypnum imponens
Thuidium delecatulum


Order your Moss Rocks!  online today.  Moss is grand.  Moss is green.  Moss is good. Make the most of it; order Moss Rocks! today.

By: Helen Yoest

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To learn more about Moss and Stone Gardens – Where Moss Rocks!, please visit our website.  Or email David Spain at

Unless otherwise noted, all photo are credited to Ken Gergle.

7 thoughts on “Making moss terrariums – or not…

  1. Andre

    Good article about mosses, now I understand why my moss is dying in the cloche. It needs more aeration. Is there a type of moss or moss like plant that will survive with little aeration and high humidity?

    1. David Spain

      My experience is that soggy soils will promote molds to form and if your working with any acrocarps in a terrarium they must dry out regularly or they will perish. ~David

      1. chris

        100% agree! Mosses are the only plant that i have yet to be able to keep alive. Every single time i try i lose them due to to much moisture (still working out the kinks. :) ).

        1. chris

          forgot to mention in reponse to the first comment. There are mosses like java moss and others that thrive underwater (if you are into aquascapes ). The main focus of his entire writings are terrestrial mosses (like hike thru the woods “oh look there’s some cool moss” moss)


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