"Natural", "real moss" and "maintenance-free" can appear on very different products. What matters is their biological state, and then the use they are intended for. This comparison helps you read a listing before buying; to pick a live species, read the guide to terrarium mosses.

Four terms not to confuse

Live moss

It can grow given suitable light, humidity and temperature. It needs the right support and regular observation. Not every live moss tolerates the warmth of a tropical terrarium, even when they are sold looking much alike.

Dried moss

Drying describes a state, not a promise of recovery. Some mosses tolerate desiccation; a dry product sold for decoration may nonetheless be dead, dyed or treated. Without a statement from the supplier, do not assume that a soak will give it back the ability to grow.

Preserved moss

Preservation aims to keep the look and the suppleness of a plant for decorative use. The processes vary from maker to maker. The result is not grown like live moss and has no need of fertiliser. Follow the product instructions, particularly about water and ambient humidity.

Decorative lichen

The "reindeer lichen" often used in plant wall art is not a moss in the botanical sense. It too can be sold preserved and coloured. A trade name that evokes a forest is not enough to make it compatible with a humid jar.

Compare according to your project

Decide first between a living composition and a decoration kept dry. Mixing the two imposes incompatible needs if the decorative part has to stay clear of watering.

The questions to ask before buying

1. Is the product explicitly sold as live, and not merely "natural"?
2. What is its botanical name, or what identification is available?
3. Has it been preserved, dyed or treated?
4. What temperature, light and humidity conditions are recommended?
5. Where does it come from: cultivation, or documented collection?
6. Is it advised for a closed terrarium, or only for dry decoration?

If the answers stay vague, ask the seller for details before you order. A very even colour is only a possible clue; a photograph cannot certify that a moss is viable.

Installing live moss

Choose a species that works with your plants and your environment. The listings for cushion moss and sheet moss are worth comparing on what they say, not just on their texture.

The guide to laying moss in a terrarium covers placement and contact with the support. Moisten it as needed, without turning the soil into a saturated sponge. Do not glue a living cushion to any old surface with a decorative adhesive.

Freshly laid moss can change appearance before it picks up. Watch the new tips and the environment. The guide to brown moss helps you sort through the possible causes; adding water every time a patch browns can make waterlogging worse.

What if you have already bought preserved moss?

Keep it for a decorative project in line with its instructions. Do not try to "wake it up" by soaking or feeding it: preservation is not a simple rest period for the plant. A coloured product can also react to damp; do not put it in the plants' growing medium without explicit compatibility.

If it is already in the jar, lift it out gently. Inspect the medium around it and replace the affected part if the product has left residues. There is no need to empty a healthy terrarium automatically; how far you go depends on what you actually see.

Building a coherent composition

For a small ecosystem, start from the miniature forest project and from plants suited to a terrarium. If you would rather have a purely decorative object with no horticultural care, choose materials for that use with your eyes open. Both projects are perfectly possible, but they are not maintained in the same way.

Sources and scope of this advice

• Verdissimo — information on preserved plants: the maker's own documentation, worth reading for the limits of its products.
• RHS — Terrariums and bottle gardens: growing conditions for living compositions.

Preservation instructions vary; no image replaces the supplier's description. Generated illustration, for editorial purposes, with no botanical identification value.