A moss terrarium is the easiest closed terrarium you can make. Moss loves exactly what a lidded glass jar provides, steady humidity and soft light, so once it is planted it needs very little from you. Here is how to make a moss terrarium step by step, which moss to use, and how to keep it green for the long term.
The short answer
Use a glass terrarium with a lid. Add a drainage layer of pebbles, a few centimetres of peat-free compost, then press pieces of moss on top and mist them. Put the lid on and keep it in bright light out of direct sun. Mist only when the moss looks dry, and lift the lid for a few hours if the glass stays heavily fogged.
Why moss suits a closed terrarium
Moss has no true roots: it takes in water through its leaves, so it thrives in damp, still air and dislikes drying out. A closed terrarium recycles moisture, as water evaporates, condenses on the glass and runs back down, which keeps the moss green with very little watering. That is also why moss and air plants do not mix: air plants need moving air and dry out between soaks, while moss wants humidity. Our guide to open and closed terrariums explains the difference.
What you need
- A glass container with a lid. Our two ball top terrariums close with a wooden ball stopper: the medium ball top (£24, about 17 x 22cm) and the extra large ball top (£45, about 23 x 23cm). Plants are not included.
- Pebbles or gravel for drainage.
- Peat-free compost, a few handfuls.
- Moss, bought from a garden centre or a specialist supplier.
- A mister or a small spray bottle, and long tweezers or a spoon for placing things.
Which moss to use
- Cushion moss forms soft, rounded domes and is the classic choice for a miniature landscape.
- Sheet moss lies flat like a carpet and is useful for covering the whole surface quickly.
- Mood moss has a tousled, wind-swept look that adds texture next to cushion moss.
Buy moss rather than taking it from the wild: in the UK it is against the law to uproot wild plants without the landowner's permission, and moss from the garden can bring in insects and mould.
How to make a moss terrarium, step by step
- Clean the glass inside and out with warm water, and dry it.
- Add a drainage layer of pebbles or gravel 2 to 3cm deep, so any excess water has somewhere to collect away from the moss.
- Add the compost, 3 to 5cm deep, sloping it gently towards the back for a sense of depth.
- Press the moss into place, green side up, firming each piece onto the compost so there are no air pockets underneath. Leave small gaps for stones or a path of sand.
- Add a feature, such as a pretty stone, a piece of bark or a small fern, which likes the same conditions.
- Mist lightly, just enough to dampen the moss, not to flood it.
- Close the lid and place the terrarium in bright light out of direct sun.
Looking after a moss terrarium
- Light: bright but indirect. Direct sun through glass overheats the jar and scorches the moss.
- Water: a closed terrarium may need misting only every few weeks. Mist when the moss looks pale or feels dry.
- Air: a little condensation in the morning is normal. If the glass stays fogged all day, lift the lid for a few hours to let it breathe.
- Tidying: pinch out yellow or brown pieces, and wipe the inside of the glass with a soft cloth when it needs it.
Common problems
- Mould or white fluff: too wet and too still. Remove the affected piece, leave the lid off for a day and mist less.
- Yellow or brown moss: usually too much sun or not enough water. Move it out of direct light and mist.
- Constant heavy fog: too much water. Open it up for a few hours until the glass clears.
Common questions
Do moss terrariums need sunlight?
They need light, but not direct sun. A bright room or a spot a little way back from a window is ideal.
How often do you water a moss terrarium?
In a closed terrarium, rarely: mist only when the moss looks dry, which may be every few weeks. An open container needs misting more often.
Can I use moss from my garden?
It can bring insects and mould into the jar, so bought moss is the safer start. Never take moss from the wild without the landowner's permission.
How long does a moss terrarium last?
With the right light and occasional airing, a closed moss terrarium can stay green for years, with a little tidying now and then.
For more planting ideas, see the best plants for a terrarium, our glass terrarium guide or, for the season, our Christmas terrarium ideas. Browse every glass terrarium.
